Bacterial Species Composition Research Articles

Rhizochemistry and soil bacterial community are tailored to natural stress gradients

Plants modulate their rhizochemistry, which affects soil bacterial communities and, ultimately, plant performance. Although our understanding of rhizochemistry is growing, knowledge of its responses to abiotic constraints is limited, especially in realistic ecological contexts. Here, we combined predictive metabolomics with soil metagenomics to investigate how rhizochemistry responded to environmental constraints and how it in turn shaped soil bacterial communities across stress gradients in the Atacama Desert. We found that rhizochemical adjustments predicted the environment (i.e. elevation, R2 between 96% and 74%) of two plant species, identifying rhizochemical markers for plant resilience to harsh edaphic conditions. These metabolites (e.g. glutamic and succinic acid, catechins) were consistent across years and could predict the elevation of two independent plant species, suggesting biochemical convergence. Next, convergent patterns in the dynamics of bacterial communities were also observed across the elevation gradient. Finally, rhizosphere predictors were associated with variation in composition and abundance of bacterial species. Biochemical markers and convergences as well as potential roles of associated predictive bacterial families reflected the requirements for plant life under extreme conditions. This included biological processes such as nitrogen and water starvation (e.g. glutamic and organic acids, Bradyrhizobiaceae), metal pollution (e.g. Caulobacteraceae) and plant development and defence (e.g. flavonoids, lipids, Chitinophagaceae). Overall, findings highlighted convergent patterns belowground, which represent exciting insights in the context of evolutionary biology, and may indicate unique metabolic sets also relevant for crop engineering and soil quality diagnostics. Besides, the results emphasise the need to integrate ecology with omics approaches to explore plant-soil interactions and better predict their responses to climate change.

Metagenomic Study Reveals Phage–Bacterial Interactome Dynamics in Gut and Oral Microbiota in Pancreatic Diseases

Individuals with pancreatic-related health conditions usually show lower diversity and different composition of bacterial and viral species between the gut and oral microbiomes compared to healthy individuals. We performed a thorough microbiome analysis, using deep shotgun sequencing of stool and saliva samples obtained from patients with chronic pancreatitis (CP), pancreatic ductal adenocarcinoma (PDAC), and healthy controls (HCs).We observed similar microbiota composition at the species level in both the gut and oral samples in PDAC patients compared to HCs, among which the most distinctive finding was that the abundance of oral-originated Fusobacterium nucleatum species did not differ between the oral and the gut samples. Moreover, comparing PDAC patients with HCs, Klebsiella oxytoca was significantly more abundant in the stool samples of PDAC patients, while Streptococcus spp. showed higher abundance in both the oral and stool samples of PDAC patients. Finally, the most important finding was the distinctive gut phage–bacterial interactome pattern among PDAC patients. CrAssphages, particularly Blohavirus, showed mutual exclusion with K. oxytoca species, while Burzaovirus showed co-occurrence with Enterobacteriaceae spp., which have been shown to be capable of inducing DNA damage in human pancreatic cells ex vivo. The interactome findings warrant further mechanistic studies, as our findings may provide new insights into developing microbiota-based diagnostic and therapeutic methods for pancreatic diseases.

Effect of antibiotics and antibiotic by-products on the chlorine resistance of biofilms in drinking water distribution systems

This study investigated the effects of tetracycline (TC) and sulfadiazine (SD), along with their degradation products, on biofilm chlorine resistance. The results showed that low concentrations of antibiotics and their degradation products promoted biofilm formation on tube surfaces and increased resistance to chlorine. There was a positive correlation between antibiotic levels, degradation products, and biofilm chlorine resistance within a specific concentration range. SD had a more significant impact on biofilm chlorine resistance compared to TC. The presence of both antibiotics and their degradation products in water led to an increase in biofilm chlorine resistance, especially when combined with 0.3 mg/L sodium hypochlorite. The study shows a positive association between antibiotic and degradation product concentrations and the biofilms' improved chlorine resistance, a phenomenon that could have major consequences for water treatment efforts. Additionally, higher concentrations of antibiotics and their degradation products were associated with reduced biodiversity within the biofilm. Overall, the findings suggest that the presence of antibiotics and their degradation products can influence biofilm formation, alter bacterial species composition, and enhance biofilm resistance to chlorine in drinking water distribution systems. This fresh perspective on the relationship between pharmaceutical residues and microbial communities in water systems could transform our approach to assuring water safety and combatting antimicrobial resistance.

Airborne bacterial and fungal species in workstations of salmon processing plants

Significant quantities of salmon are processed daily in the industry's indoor facilities. Occupational exposure contributes to an individual's exposome. The aim of this study is to obtain knowledge about potential exposure to viable airborne species of bacteria and fungi as related to workstations in the salmon processing industry. The study was conducted in nine salmon plants along the Norwegian coast over one or two days with a one-year interval. The MAS100 was used for sampling and MALDI-TOF MS for species identification. The geometric mean concentrations of bacteria and fungi were 200 CFU/m3 and 50 CFU/m3, respectively, with the highest concentrations of bacteria found in slaughtering areas and fungi in trimming of fillets. In total 125 gram-negative and 90 gram-positive bacterial and 32 different fungal species were identified. Some genera were represented by several species e.g. Chryseobacterium (15 species), Flavobacterium (13 species), Microbacterium (12 species), Pseudomonas (37 species), and Psychrobacter (13 species). Risk class 2 (RC2, human pathogens) were found in all types of workstations and plants. Seventeen bacterial species belong to RC2, some were fish pathogens, food spoilage bacteria, or species causing foodborne disease. Among fungi, Aspergillus nidulans was frequently detected across different workstations and plants. In conclusion, bacterial and fungal concentrations were low. Fish and sea-related bacteria were found along the salmon processing line. Bacterial concentrations and species compositions differ between workstations. No particular bacterial or fungal species constituted a large fraction of all airborne species. Based on the presence of human pathogens, using protective gloves is important for the workers. The presence of human and fish pathogens and food spoilage bacteria reveals air as a transmission route for bacteria, potentially affecting workers, consumers, fish, and hygiene of processing equipment. To limit the spread of these bacteria an interdisciplinary cooperation with a One Health perspective may be relevant.

Geochemistry and microbiology of boreal alluvial soil under salinisation

Soil salinisation in taiga landscapes is in most cases caused by anthropogenic activities. The study was carried out in Perm region (Russia) on the territory of the Verkhnekamskoe Potash Deposit. The inflow of sodium chloride drainage water into ground and surface waters during the production of potash fertilisers contributed to the technogenic salinisation of river valleys in the taiga zone. The purpose of the research was to investigate the microbial composition and chemical properties of alluvial soils in the area affected by NaCl waters in the Lyonva River valley. The chemical properties of soils were determined standard methods such as potentiometric method, titration, and spectrophotometry. The microbial community was determined by 16 s rRNA gene metagenomic analysis. The soil's mineralogical composition was determined using a binocular microscope and diffractometer for XRD. The morphology and microstructure of the samples has been studied using an analytical scanning electron microscope. In Solonchaks, an interdependence of salinity and bacterial species composition was discovered, along with the bacteria's geochemical processes. The topsoil contains a considerable amount of toxic salts, ranging from 5.9 to 17%. The ratio of exchangeable cations in the soil absorption complex changes when exchangeable calcium is replaced by sodium. Salinisation caused the neutralisation of acidic alluvial soils. Bacteria originating from marine and highly mineralised environments predominate in the soil. The soils are dominated by bacteria originating from marine and highly mineralised environments, such as Proteobacteria, Shewanella (75–79%), Thiomicrospira (26%), Desulfuromonas, Marinomonas and Idiomarina (9–10%), Alicyclobacillus (4%). The correlation revealed the connection of some taxa with ions of aqueous extract, as well as with exchangeable sodium, mobile iron and total sulphur. Some bacteria promote azonal geochemical processes within alluvial forest soil, such as the reduction of iron and manganese, the production of sulphides, and the oxidation of sulphur, hydrogen, and iron. Sulphide accumulation resulting in the formation of a hydrotroilite horizon (FeS × nH2O) and iron-bearing formations were found on the soil surface. Studying the properties and degree of soil disturbance makes it possible to identify the contribution of enterprises to environmental pollution, as well as to apply new methods for monitoring, purifying, and storing potassium waste.

Association between Fecal Bile Acids and Levodopa Response in Patients with Parkinson's Disease.

Levodopa is the mainstay of treatments for Parkinson's disease (PD), but large heterogeneity exists in patient response. Increasing evidence implicates bile acids (BAs) involved in the pathogenesis of PD. Furthermore, BAs have also participated in drug bioavailability. However, the impact of BAs on levodopa response (LR) has not been investigated. This study evaluated the association between fecal BAs and LR. Levodopa challenge test (LCT) was conducted in 92 PD patients to assess LR. A total of 36 fecal BAs and plasma levodopa concentrations were detected using LC-MS/MS. The difference of BAs between subgroups with bottom and top 30% LR were analyzed and fecal samples from the two groups were collected for metagenomic shotgun analysis. No fecal BAs were significantly correlated with LR, except for chenodeoxycholic acid-3-β-D-glucuronide (CDCA-3-β-glucuronide, R = -0.228, p-value = 0.039). We found no significant difference in BAs between subgroups with bottom and top 30% LR. What is more, no significant changes in bacterial species composition related to bile acids metabolism or in the proportional representation of genes encoding known bile acids enzymes were observed between the groups. Overall, our data do not support an association between fecal BAs and levodopa response in PD patients. More precise macro-metabolomic approaches are needed to reveal the potential association between gut microbial interactions and the treatment effect of levodopa.

Responses of soil fungal and bacterial communities to long-term organic and inorganic nitrogenous fertilizers in an alpine agriculture

Although nitrogen fertilizer is an important measure to increase grain yield, response of soil microbial community to nitrogen fertilizer is still unclear in alpine regions. Based on a long-term (>10 years) nitrogen fertilizer experiment (control, CF: chemical fertilizer, SM: sheep manure; CS: chemical fertilizer + sheep manure) in an alpine agroecosystem of the Lhasa, Xizang, responses of soil bacteria and fungi communities to nitrogen fertilizer was investigated. The CF treatment reduced fungi operational taxonomic unit (OTU) by 13.08 %, phylogenetic diversity by 11.13 % at 10–20 cm, but increased fungi guild number at 0–10 cm by 17.71 %. The SM treatment reduced fungi OTU at 10–20 cm by 11.82 %. Compared to CF and SM treatments, CS treatment had stronger positive effects on bacterial α-diversity, considering that CS treatment but not CF and SM treatments increased bacterial mean nearest taxon distance, species Shannon and Simpson at 10–20 cm. The CF, SM and CS treatments altered fungal community composition at 0–10 and 10–20 cm, bacterial community composition at 10–20 cm, and bacterial species composition at 0–10 cm. The CF and CS treatments altered bacterial phylogenetic composition at 0–10 cm, and the SM and CS treatments altered bacterial functional composition at 0–10 cm. The decreased magnitude of the relative abundance of symbiotroph fungi caused by CS treatment (90.44 %) was stronger than that (65.14 % and 53.62 %) caused by CF and SM treatments at 10–20 cm. Therefore, the SM and CS treatments had stronger effects on soil bacterial functional composition, but the CF treatment had stronger effects on fungal α-diversity. Compared with single application of organic or inorganic nitrogen fertilizer, mixed application of organic and inorganic nitrogen fertilizer was more beneficial to the maintenance and improvement of soil bacterial diversity, but caused more reduction of soil symbiotic fungi and in turn greater potential risk. These scientific findings observed by this study can provide guidance for fertilizer management and soil fertility improvement.

Comparative microbiome diversity in root-nodules of three Desmodium species used in push-pull cropping system.

Desmodium species used as intercrops in push-pull cropping systems are known to repel insect-pests, suppress Striga species weeds, and shift soil microbiome. However, the mechanisms through which Desmodium species impact the soil microbiome, either through its root exudates, changes in soil nutrition, or shading microbes from its nodules into the rhizosphere, are less understood. Here, we investigated the diversity of root-nodule microbial communities of three Desmodium species- Desmodium uncinatum (SLD), Desmodium intortum (GLD), and Desmodium incanum (AID) which are currently used in smallholder maize push-pull technology (PPT). Desmodium species root-nodule samples were collected from selected smallholder farms in western Kenya, and genomic DNA was extracted from the root-nodules. The amplicons underwent paired-end Illumina sequencing to assess bacterial and fungal populations. We found no significant differences in composition and relative abundance of bacterial and fungal species within the root-nodules of the three Desmodium species. While a more pronounced shift was observed for fungal community compositions compared to bacteria, no significant differences were observed in the general diversity (evenness and richness) of fungal and bacterial populations among the three Desmodium species. Similarly, beta diversity was not significantly different among the three Desmodium species. The root-nodule microbiome of the three Desmodium species was dominated by Bradyrhizobium and Fusarium species. Nevertheless, there were significant differences in the proportion of marker gene sequences responsible for energy and amino acid biosynthesis among the three Desmodium species, with higher sequence proportions observed in SLD. There is no significant difference in the microbial community of the three Desmodium species used in PPT. However, root-nodule microbiome of SLD had significantly higher marker gene sequences responsible for energy and amino acid biosynthesis. Therefore, it is likely that the root-nodules of the three Desmodium species host similar microbiomes and influence soil health, consequently impacting plant growth and agroecosystem functioning.

Gut Microbial Composition of Cyprinella lutrensis (Red Shiner) and Notropis stramineus (Sand Shiner): Insights from Wild Fish Populations

The gut microbiome is a highly intricate ecosystem that exerts a pivotal influence on the host’s physiology. Characterizing fish microbiomes is critical to understanding fish physiology and health, but little is known about the ecology and colonization dynamics of microorganisms inhabiting fish species. In this study, we investigated the bacterial communities of two small-bodied fish species, Cyprinella lutrensis (red shiner) and Notropis stramineus (sand shiner), two fish species where gut microbiomes have not been investigated previously and surrounding waters, collected from rivers in Nebraska, USA. Our study focused on evaluating microbial diversity in small-bodied fish and identifying autochthonous microbes present within these species irrespective of location to better understand bacterial community composition and possible roles of such bacterial species. Our results revealed that both red shiner and sand shiner exhibited gut bacterial communities dominated by typical bacterial phyla found in freshwater fish. The phylum Bacteroidota was minimally abundant in both species and significantly lower in relative abundance compared to the surrounding water microbial community. Furthermore, we found that the gut microbiomes of red shiner and sand shiner differed from the microbial community in the surrounding water, suggesting that these fish species contain host-associated bacterial species that may provide benefits to the host such as nutrient digestion and colonization resistance of environmental pathogens. The fish gut bacterial communities were sensitive to environmental conditions such as turbidity, dissolved oxygen, temperature, and total nitrogen. Our findings also show bacterial community differences between fish species; although they shared notable similarities in bacterial taxa at phyla level composition, ASV level analysis of bacterial taxa displayed compositional differences. These findings contribute to a better understanding of the gut bacterial composition of wild, freshwater, small-bodied fish and highlight the influence of intrinsic (host) and environmental factors on shaping the bacterial composition.

Bacterial Community Characteristics and Roles in Nitrogen Transformation in Industrial Farming Systems of Litopenaeus vannamei

Industrial farming is one of the main farming systems used for L. vannamei, and it is also the main direction of development in the future. To investigate the role of the bacterial community in nitrogen transformation in industrial L. vannamei farming systems, we studied the concentration of nitrogen compounds, the bacterial community using 16S rRNA sequencing, and nitrogen cycling genes’ abundance using absolute quantitative PCR in aquaculture water (using seawater (WD) and groundwater mixed with seawater (CY)) and analyzed the correlations between them using a person analysis. The results showed that the bacterial α-diversity index (ACE, Shannon, and Sobs) significantly changed during culture in WD but not in CY. Bacterial community species composition analysis and linear discriminant analysis effect size (LEfSe analysis) revealed that Cyanobiaceae and Microbacteriaceae were the dominant bacteria and biomarkers in WD. Vibrionaceae, Ateromonadaceae, Microbacteriaceae, Saprospiraceae, and Cryomorphaceae were the dominant bacteria and biomarkers in CY. A functional annotation of procaryotic taxa (FAPROTAX) analysis revealed that the bacterial community in WD exhibited a greater phototrophic activity at early culture stages, while at the same stage, CY exhibited strong nitrate reduction. A correlation analysis of nitrogen cycling genes and environmental factors revealed that napA, narG, ureC, amoA, and nirK were significantly correlated with the concentrations of total ammonia nitrogen (TAN), nitrite (NO2−-N), nitrate (NO3−-N), and total nitrogen (TN) in WD. In CY, amoA was positively correlated and napA and nirK were negatively correlated with TAN and TN concentrations. A correlation analysis between bacterial abundance and environmental factors revealed that Flavobacteriaceae, Saprospiraceae, Cryomorphaceae, Cyanobiaceae, Halieaceae, and Cyclobacteriaceae were significantly correlated with the concentrations of TAN and NO2−-N. The above results indicated that the bacterial community in industrial shrimp farming systems changed under different conditions, with consequent changes in the abundance of genes being involved in the nitrogen cycle and in this biogeochemical process in the water. Our study facilitates further understanding of microbes and their functions in nitrogen cycling in industrial shrimp farming systems.

Characterisation of the urinary microbiome of a frog, and the effect of antibiotics on bacterial abundance and sperm viability during refrigerated storage

Reproductive technologies are increasingly being adopted to improve the conservation management of threatened species. The storage and transport of sperm is a vital aspect of the practical implementation of reproductive technologies, however, bacterial contamination during the storage and transport of sperm samples presents a biosecurity risk and can contribute to a reduction in sperm longevity during storage. The present study: 1) characterised the urinary microbiome (bacterial species composition and abundance) using culture-independent 16S rRNA sequencing; 2) quantified the effect of various doses of gentamicin and streptomycin-penicillin on bacterial abundance (colony-forming units; CFUs) and; 3) quantified the effect of antibiotic supplementation on the sperm viability (proportion live/dead) of spermic urine during a 12-day cold-storage period, using the common eastern froglet, Crinia signifera. Overall, urine samples were found to host a diverse array of bacteria, dominated by the phyla Proteobacteria, Firmicutes, and Bacteroidetes. Bacterial abundance was significantly reduced in all antibiotic treatment groups compared to the control group. Antibiotic supplementation had no effect on sperm viability between day 0 and day 6 of storage, however both antibiotic treatments significantly improved sperm viability from days 9 to 12 of storage compared to the control group. Overall, the results of this study provide novel insight into the urinary microbiome, being the first to use a metagenomics approach to characterise the bacterial community present in the urine of an amphibian. Importantly, this study provides evidence that antibiotic supplementation with either gentamicin or streptomycin-penicillin, minimises bacterial proliferation and improves sperm viability during cold storage. These findings will contribute to the development of biosecurity protocols aimed at reducing the risk of disease transmission and cross-infection from unwanted bacteria and infectious agents in amphibian captive breeding programs.

The Impact of Early-Life Cecal Microbiota Transplantation on Social Stress and Injurious Behaviors in Egg-Laying Chickens.

Injurious behaviors (i.e., aggressive pecking, feather pecking, and cannibalism) in laying hens are a critical issue facing the egg industry due to increased social stress and related health and welfare issues as well as economic losses. In humans, stress-induced dysbiosis increases gut permeability, releasing various neuroactive factors, causing neuroinflammation and related neuropsychiatric disorders via the microbiota-gut-brain axis, and consequently increasing the frequency and intensity of aggression and violent behaviors. Restoration of the imbalanced gut microbial composition has become a novel treatment strategy for mental illnesses, such as depression, anxiety, bipolar disorder, schizophrenia, impulsivity, and compulsivity. A similar function of modulating gut microbial composition following stress challenge may be present in egg-laying chickens. The avian cecum, as a multi-purpose organ, has the greatest bacterial biodiversity (bacterial diversity, richness, and species composition) along the gastrointestinal tract, with vitally important functions in maintaining physiological and behavioral homeostasis, especially during the periods of stress. To identify the effects of the gut microbiome on injurious behaviors in egg-laying chickens, we have designed and tested the effects of transferring cecal contents from two divergently selected inbred chicken lines on social stress and stress-related injurious behaviors in recipient chicks of a commercial layer strain. This article reports the outcomes from a multi-year study on the modification of gut microbiota composition to reduce injurious behaviors in egg-laying chickens. An important discovery of this corpus of experiments is that injurious behaviors in chickens can be reduced or inhibited through modifying the gut microbiota composition and brain serotonergic activities via the gut-brain axis, without donor-recipient genetic effects.

Bacterial community changes in strawberry fruits (Fragaria × ananassa variety "Monterey") from farm field to retail market stands, an indicator of postharvest contamination.

Strawberry (Fragaria × ananassa) fruits are vulnerable to bacterial contamination; some species are pathogenic and can affect human health. Comprehending the bacterial composition and diversity at different ripe stages is a key determinant of the fruit health, productivity, and quality. An amplicon metagenomic approach on the 16S rRNA region was used to identify the bacterial diversity in exocarp of fruits collected from a farm field at two ripe stages: breaking (white, phase two) and ripe (red, phase four) and purchased from different retail market stands at ripe (red, phase four, ready-to-eat) stage. Besides, the fruit quality was assessed. Strawberries carries a high microorganisms diversity, with Pseudomonaceae, Yearsiniaceae, and Hafniaceae being the most abundant families across the samples. Among the groups, Pseudomonaceae and Clostridiaceae were the most abundant families at breaking (phase two) and ripe (phase four), whereas Yearsiniaceae, Hafniaceae, Aeromonadaceae, and Streptococcaceae were the most abundant families in the market group. Although samples from group four-field and market were at the same ripe stage, the bacterial species composition was divergent. Serratia spp. were prevalent (above 60%) in samples collected from the market group, and Pseudomonas (above 70%) species were mostly found in the samples collected from the field settings regardless of the phase. Besides, Escherichia coli and Salmonella enterica were detected in the ready-to-eat samples from both the field and the market, while Enterococcus gallinarum was detected in the samples that originated from the market. Interestingly, Shewanella putrefaciens and Shewanella profunda, two human opportunistic pathogens, were detected in the fruits from the market only. According to alpha and beta diversity analyses, strawberry fruits displayed significant differences (P < 0.05) in bacterial communities within the ripe group, with the samples from the market showing the most bacterial diversity. Although we do not directly correlate the quality attributes with bacterial diversity, the results indicated a clear separation between groups according with their ripe stage and origin. This study provides a comprehensive framework of the bacterial diversity throughout the transition from unripe to ripe strawberries which may aid in the development of preventative measures to manage the postharvest contamination.

Metagenome-assembled genome reveals species and functional composition of Jianghan chicken gut microbiota and isolation of Pediococcus acidilactic with probiotic properties

BackgroundChickens are one of the most widely farmed animals worldwide and play a crucial role in meat and egg production. Gut microbiota is essential for chickens’ health, disease, growth, and egg production. However, native chickens such as Jianghan chickens have better meat and egg production quality than centralized chickens, their intestinal microbial diversity is richer, and the potential gut microbial resources may bring health benefits to the host.ResultsThe bacterial species composition in the gut microbiota of Jianghan chickens is similar to that of other chicken breeds, with Phocaeicola and Bacteroides being the most abundant bacterial genera. The LEfSe analysis revealed significant differences in species composition and functional profiles between samples from Jingzhou and the other three groups. Functional annotation indicated that the gut microbiota of Jianghan chickens were dominated by metabolic genes, with the highest number of genes related to carbohydrate metabolism. Several antibiotic resistance genes (ARGs) were found, and the composition of ARGs was similar to that of factory-farmed chickens, suggesting that antibiotics were widely present in the gut microbiota of Jianghan chickens. The resistance genes of Jianghan chickens are mainly carried by microorganisms of the Bacteroidota and Bacillota phylum. In addition, more than 829 isolates were selected from the microbiota of Jianghan chickens. Following three rounds of acid and bile tolerance experiments performed on all the isolated strains, it was determined that six strains of Pediococcus acidilactici exhibited consistent tolerance. Further experiments confirmed that three of these strains (A4, B9, and C2) held substantial probiotic potential, with P. acidilactici B9 displaying the highest probiotic potential.ConclusionsThis study elucidates the composition of the intestinal microbiota and functional gene repertoire in Jianghan chickens. Despite the absence of antibiotic supplementation, the intestinal microbial community of Jianghan chickens still demonstrates a profile of antibiotic resistance genes similar to that of intensively reared chickens, suggesting resistance genes are prevalent in free-ranging poultry. Moreover, Jianghan and intensively reared chickens host major resistance genes differently, an aspect seldom explored between free-range and pastured chickens. Furthermore, among the 829 isolates, three strains of P. acidilatici exhibited strong probiotic potential. These findings provide insights into the unique gut microbiota of Jianghan chickens and highlight potential probiotic strains offering benefits to the host.C1P5UZATuvCf_fXF2a8dUFVideo

ДИНАМИКА КАЧЕСТВЕННОГО И КОЛИЧЕСТВЕННОГО СОСТАВА МИКРОБИОМА ВНУТРЕННИХ ПОВЕРХНОСТЕЙ МЕЖДУНАРОДНОЙ КОСМИЧЕСКОЙ СТАНЦИИ ЗА ПЕРИОД НАБЛЮДЕНИЙ С 2016 ПО 2022 Г.

Residents of the International Space Station (ISS) are various types of bacteria that can act as potential biodegraders of structural materials, which entails disruptions in the operation of various equipment and, indirectly, provoke medical risks and affect the health of crew members with reduced immunity. Since the beginning of ISS exploitation sanitary and microbiological monitoring of the habitat has been carried out for the purpose of timely detection and inactivation of potentially dangerous strains. The study was conducted to investigate the dynamics of the composition and number of bacterial strain species detected on the internal surfaces of the ISS interior and equipment for the period covering from Expedition 46 to Expedition 67 (2016–2022). Samples collected from ISS interior surfaces were grown on nutrient media. Strains were identified by 16S RNA sequencing and MALDI-TOF analysis. The results obtained showed that the number of bacterial community species increases with the increase of the ISS RS operation period. However, this growth was not linear, but was a wave-like repetitive process of changing phases of activation and stagnation of the microbiome. During the period of work of Expeditions 46-67, species of the genera Bacillus and Staphylococcus dominated in the microbiome. Among representatives of the genus Bacillus, the species B. licheniformis dominated. The predominance of bacteria of this genus, apparently, is due to their high resistance to physical and chemical parameters of the ISS habitat, including DNA-damaging factors, such as increased radiation background, which, in turn, can be explained by their ability to spore formation. The results obtained once again indicate the high evolutionary plasticity of B. licheniformis strains, which we discovered earlier in other studies.

Diversity and composition of active and total bacteria in rhizospheric soil in response to continuous cropping years of Panax notoginseng.

The synchronous research and analysis of total and active soil microbial communities can provide insight into how these communities are impacted by continuous cropping years and pathogen infection. The diversity of total and active bacteria in rhizospheric soil of 2-year-old and 3-year-old healthy and diseased Panax notoginseng can comprehensively reveal the bacterial response characteristics in continuous cropping practice. The results showed that 4916 operational taxonomic units (OTUs) were found in the rhizospheric soil bacterial community of P. notoginseng at the DNA level, but only 2773 OTUs were found at the RNA level. The rhizospheric environment had significant effects on the active and bacterial communities, as indicated by the number of OTUs, Shannon, Chao1, Faith's phylogenetic diversity (Faith's PD), and Simpson's diversity indexes. The DNA level can better show the difference in diversity level before and after infection with root rot. The bacterial Chao1 and Faith's PD diversity indexes of 2-year-old root rot-diseased P. notoginseng rhizospheric soil (D2) were higher than that of healthy plants, while the bacterial Shannon diversity index of 3-year-old root rot-diseased P. notoginseng rhizospheric soil (D3) was the lowest in the total bacteria. Principal coordinate analysis (PCoA) illustrated that the total bacterial species composition changed markedly after root rot disease. There were significant differences in the composition of active bacterial species between the 2-year and 3-year rhizospheres. In conclusion, the total and active edaphic rhizospheric bacterial communities could provide important opportunities to understand the responses of bacteria to continuous cropping of P. notoginseng.

Maternal transmission of bacterial microbiota during embryonic development in a viviparous lizard.

The maternal transmission of microbiota during embryonic development of vertebrates is still poorly understood. Here, we used high-throughput sequencing of the 16S rRNA bacterial genes to determine the bacterial communities in the gastrointestinal tract and amniotic environment, i.e., the amniotic fluid, amniotic membrane and extraembryonic yolk, of embryos at the last stage of development of the viviparous lizard Sceloporus grammicus Wiegmann, 1828. We compared these communities to those found in the maternal intestine, mouth, cloaca, and the aseptic ventral skin as a control of the aseptic technique. Our results showed that bacterial 16S rRNA genes were present in the embryos of S. grammicus. Their diversity was lower and more similar in composition between individuals than those found in the maternal tissues. This suggests that a strong control exists on the transmission of bacteria from the mother to the embryos. We found 78% of the embryonic amplicon sequence variants (ASVs) in the maternal bacterial microbiota, suggesting that the transmission of bacteria from the mother to the embryos is a continuous process and some bacteria may have been transferred during early embryonic stages. The embryonic bacteria were found to overlap mostly with those found in the mouth and aseptic ventral skin of the mother, although it is difficult to conclude that the shared ASVs originated from these maternal tissues. Our study provides evidence of microbiota vertical transfer during embryonic development in the animal kingdom. It also highlights that this maternal transmission could be included in the maternal effects that impact the offspring.IMPORTANCEWe investigated the presence and diversity of bacteria in the embryos of the viviparous lizard Sceloporus grammicus and their amniotic environment. We compared this diversity to that found in the maternal intestine, mouth, and cloaca. We detected bacterial DNA in the embryos, albeit with a lower bacterial species diversity than found in maternal tissues. Most of the bacterial species detected in the embryos were also found in the mother, although not all of them. Interestingly, we detected a high similarity in the composition of bacterial species among embryos from different mothers. These findings suggest that there may be a mechanism controlling the transmission of bacteria from the mother to the embryo. Our results highlight the possibility that the interaction between maternal bacteria and the embryo may affect the development of the lizards.

Comparisons of the Oral Microbiota from Seven Species of Wild Venomous Snakes in Taiwan Using the High-Throughput Amplicon Sequencing of the Full-Length 16S rRNA Gene.

A venomous snake's oral cavity may harbor pathogenic microorganisms that cause secondary infection at the wound site after being bitten. We collected oral samples from 37 individuals belonging to seven species of wild venomous snakes in Taiwan, including Naja atra (Na), Bungarus multicinctus (Bm), Protobothrops mucrosquamatus (Pm), Trimeresurus stejnegeri (Ts), Daboia siamensis (Ds), Deinagkistrodon acutus (Da), and alpine Trimeresurus gracilis (Tg). Bacterial species were identified using full-length 16S rRNA amplicon sequencing analysis, and this is the first study using this technique to investigate the oral microbiota of multiple Taiwanese snake species. Up to 1064 bacterial species were identified from the snake's oral cavities, with 24 pathogenic and 24 non-pathogenic species among the most abundant ones. The most abundant oral bacterial species detected in our study were different from those found in previous studies, which varied by snake species, collection sites, sampling tissues, culture dependence, and analysis methods. Multivariate analysis revealed that the oral bacterial species compositions in Na, Bm, and Pm each were significantly different from the other species, whereas those among Ts, Ds, Da, and Tg showed fewer differences. Herein, we reveal the microbial diversity in multiple species of wild snakes and provide potential therapeutic implications regarding empiric antibiotic selection for wildlife medicine and snakebite management.

Improve tea quality by enhancing the stability of bacterial community interaction and nitrogen-fixing function in pecan-tea interplanted plantation

Using the 16 S rDNA high-throughput sequencing, the effects of interplanted pecan (Carya illinoinensis) in a typical tea (Camellia sinensis) plantation on soil bacterial species composition and marker species were comparatively analyzed to determine whether nested pecan increases soil microbial diversity in the tea tree rhizosphere. We explored the effects of the underlying mechanisms of this complex ecosystem on tea quality by determining soil physicochemical properties using two types of planting modes: intercropping with pecan versus tea tree monoculture. Our results showed that Rhizobium (Allorhizobium, Neorhizobium, Pararhizobium, and Rhizobium), and Enterobacter, had pollution-degrading effects and were enriched in the soil bacterial communities of the pecan interplanted model. There was a significant enrichment of prebiotic functional bacteria, such as Pedosphaeraceae and Coriobateriaceae_UCG-002, which stimulate plant growth and improve disease resistance, while the functions of Chloroflexi and Firmicutes, which are dominant denitrifying bacteria in the soil, were inhibited. The average degree of soil microbial co-occurrence network increased from 13.40 to 18.17, and the number of nodes in the network increased from 117 to 166, indicating that the network increased in complexity and decreased in mutual exclusivity, and the complex interactions among bacterial populations tended to be stable. The intercropping mode reduced the phenol/ammonia ratio in tea from 2.37 to 1.38, improving the tea quality. Therefore, the soil microbial community composition under this complex model promotes material cycling in microecosystems and effectively reduces the transmission risk of soil-borne diseases. The soil microbial community structure of the tea rhizosphere could be re-balanced and shifted toward a more favorable tea quality formation by the introduction of pecan into tea plantations.

Ensiling hybrid Pennisetum with lactic acid bacteria or organic acids improved the fermentation quality and bacterial community.

The aim of this study was to compare the effect of different additives on nutritional quality, fermentation variables and microbial diversity of hybrid Pennisetum silages. A control (CK - no additives) and seven treatments were tested, namely, Lactiplantibacillus plantarum (LP), Lentilactobacillus buchneri (LB), propionic acid (PA), calcium propionate (CAP), LP + LB; LP + PA and LP + CAP. In comparison with CK, all treatments increased the contents of crude protein and lactic acid, decreased the content of butyric acid, and altered the bacterial communities of the silage. Except for the CAP and LP + CAP treatments, the additives decreased pH and the ammonia nitrogen:total nitrogen (NH3-N:TN) ratio. The results of principal component analysis revealed that the PA, LP + PA and LP + LB treatments ranked as the top three silages. The PA and LP + PA treatments exhibited higher water-soluble carbohydrate content, but lower pH, and NH3-N:TN ratio than the other treatments. With the PA and LP + PA treatments, the relative abundances of Lactobacillus and Enterobacter decreased, and of Proteobacteria and Delftia increased, while the carbohydrate metabolism of the microorganisms improved. The LP and LB treatments reduced the Shannon and Simpson diversities. In the beta diversity, PA and LP + PA separated from the other treatments, indicating that there were differences in the composition of bacterial species. The relative abundance of Lactobacillus increased in the LP and LB treatments and of Leucanostoc and Weissella increased in the CAP and LP + CAP treatments. In summary, the addition of L. plantarum, L. buchneri, propionic acid, calcium propionate, and their combinations improved fermentation quality, inhibited harmful bacteria and conserved the nutrients of hybrid Pennisetum.