Bacterial Amplicon Sequence Variants Research Articles

Bivalve microbiomes are shaped by host species, size, parasite infection, and environment.

Many factors affect an organism's microbiome including its environment, proximity to other organisms, and physiological condition. As filter feeders, bivalves have highly plastic microbiomes that are especially influenced by the surrounding seawater, yet they also maintain a unique core set of microbes. Using 16S ribosomal RNA sequencing, we characterized the bacterial microbiomes of four species of bivalves native to the Mid-Atlantic East Coast of North America: Crassostrea virginica, Macoma balthica, Ameritella mitchelli, and Ischadium recurvum and assessed the impact of their external environment, internal parasites, and size on their microbial communities. We found significant differences in bacterial amplicon sequence variants (ASVs) across species, with each species harboring a core ASV present across all individuals. We further found that some C. virginica co-cultured with I. recurvum had high abundances of the I. recurvum core ASV. We identified ASVs associated with infection by the parasites Perkinsus marinus and Zaops ostreum as well others associated with bivalve size. Several of these ASV are candidates for further investigation as potential probiotics, as they were found positively correlated with bivalve size and health. This research represents the first description of the microbiomes of A. mitchelli, I. recurvum, and M. balthica. We document that all four species have highly plastic microbiomes, while maintaining certain core bacteria, with important implications for growth, health, and adaptation to new environments.

Microcystis abundance is predictable through ambient bacterial communities: A data-oriented approach

The number of cyanobacterial harmful algal blooms (cyanoHABs) has increased, leading to the widespread development of prediction models for cyanoHABs. Although bacteria interact closely with cyanobacteria and directly affect cyanoHABs occurrence, related modeling studies have rarely utilized microbial community data compared to environmental data such as water quality. In this study, we built a machine learning model, the multilayer perceptron (MLP), for the prediction of Microcystis dynamics using both bacterial community and weekly water quality data from the Daechung Reservoir and Nakdong River, South Korea. The modeling performance, indicated by the R2 value, improved to 0.97 in the model combining bacterial community data with environmental factors, compared to 0.78 in the model using only environmental factors. This underscores the importance of microbial communities in cyanoHABs prediction. Through the post-hoc analysis of the MLP models, we revealed that nitrogen sources played a more critical role than phosphorus sources in Microcystis blooms, whereas the bacterial amplicon sequence variants did not have significant differences in their contribution to each other. Similar to the MLP model results, bacterial data also had higher predictability in multiple linear regression (MLR) than environmental data. In both the MLP and MLR models, Microscillaceae showed the strongest association with Microcystis. This modeling approach provides a better understanding of the interactions between bacteria and cyanoHABs, facilitating the development of more accurate and reliable models for cyanoHABs prediction using ambient bacterial data.

Characterization and analysis of dynamic changes of microbial community associated with grape decay during storage

The rot caused by pathogens during the storage of table grapes is an important factor that affects the development of the grape industry and food safety, and it cannot be ignored. The development of innovative methods for pathogen control should be based on a comprehensive understanding of the overall microbial community changes that occur during grape storage. The study aims to investigate the relationship between the native microbiota (including beneficial, pathogenic and spoilage microorganisms) on grape surfaces and the development of disease during grape storage. In this study, the bacteria and fungi present on grape surfaces were analyzed during storage under room temperature conditions using high-throughput sequencing. During the storage of grapes at room temperature, observable diseases and a noticeable decrease in quality were observed at 8 days. Microbial community analysis showed that 4996 bacterial amplicon sequence variants (ASVs) and 488 fungal ASVs were determined. The bacterial richness exhibited an initial increase followed by a subsequent decrease. However, the diversity exhibited a distinct pattern of gradual decrease. The fungal richness and community diversity both exhibit a gradual decrease during the storage of grapes. Fungal β-diversity analysis showed that despite the absence of rot and the healthy state of grapes on the first and fourth days, the fungal β-diversity exhibited a significant difference. The analysis of changes in genera abundances suggested that Candidatus Profftella and Aspergillus exhibited dominance in the rotting grape at 16 days, which are the main pathogens that caused disease in the present study. The co-occurrence networks among the microbial showed that the Candidatus proftella genera has a positive correlation with Aspergillus niger, indicating that they work together to cause disease and promote growth in grapes. Predicting the function of bacterial communities found that the microorganisms associated with lipid metabolism at 4 days play an important role in the process of postharvest decay of grapes.

A Survey of Zoonotic Bacteria in the Spleen of Six Species of Rodents in Panama

Emerging zoonotic diseases are one of the main threats to human and animal health. Among the agents with the potential for zoonoses, those of bacterial origin have great relevance in Public Health. Rodents are considered one of the main reservoirs of pathogens that represent a risk to human health or animal species. We used massive 16S ribosomal RNA gene amplicon sequencing to survey bacteria present in the spleen of six species of rodents in Panama in order to identify bacterial taxa with zoonotic potential in the country. We found 3352 bacterial Amplicon Sequence Variants (ASVs, i.e., phylogenetic species) in the spleen of six rodent species surveyed (Liomys adspersus, Melanomys caliginosus, Mus musculus, Proechimys semispinosus, Rattus rattus, Zygodontomys brevicauda). This bacterial community was represented by 25 phyla, 55 classes, 140 orders, 268 families, and 508 genera. The three predominant phyla were Actinobacteria, Firmicutes, and Proteobacteria, and the five predominant classes were Actinobacteria, Alpha- and Gammaproteobacteria, Bacilli, and Clostridia. There were seven high-abundance genera: Acinetobacter, Bartonella, Cutibacterium, Enterococcus, Sarcina, Staphylococcus, and Wolbachia. Genera found with less abundance included Bradyrhizobium, Chryseobacterium, Clostridium, Corynebacterium, Lactobacillus, Pseudonocardia, Rhodococcus, and Sphingomonas. Some of these genera (high or low abundance) have clinical importance. The identification of bacterial taxa with zoonotic potential in rodent species performed here allows us to have surveillance mechanisms for these pathogens and to be able to recognize localities to be prioritized for prevention of transmission and outbreaks, thus being of value for public health in Panama.

Rhizosphere competent inoculants modulate the apple root-associated microbiome and plant phytoalexins.

Modulating the soil microbiome by applying microbial inoculants has gained increasing attention as eco-friendly option to improve soil disease suppressiveness. Currently, studies unraveling the interplay of inoculants, root-associated microbiome, and plant response are lacking for apple trees. Here, we provide insights into the ability of Bacillus velezensis FZB42 or Pseudomonas sp. RU47 to colonize apple root-associated microhabitats and to modulate their microbiome. We applied the two strains to apple plants grown in soils from the same site either affected by apple replant disease (ARD) or not (grass), screened their establishment by selective plating, and measured phytoalexins in roots 3, 16, and 28days post inoculation (dpi). Sequencing of 16S rRNA gene and ITS fragments amplified from DNA extracted 28 dpi from different microhabitat samples revealed significant inoculation effects on fungal β-diversity in root-affected soil and rhizoplane. Interestingly, only in ARD soil, most abundant bacterial amplicon sequence variants (ASVs) changed significantly in relative abundance. Relative abundances of ASVs affiliated with Enterobacteriaceae were higher in rhizoplane of apple grown in ARD soil and reduced by both inoculants. Bacterial communities in the root endosphere were not affected by the inoculants but their presence was indicated. Interestingly and previously unobserved, apple plants responded to the inoculants with increased phytoalexin content in roots, more pronounced in grass than ARD soil. Altogether, our results indicate that FZB42 and RU47 were rhizosphere competent, modulated the root-associated microbiome, and were perceived by the apple plants, which could make them interesting candidates for an eco-friendly mitigation strategy of ARD. KEY POINTS: • Rhizosphere competent inoculants modulated the microbiome (mainly fungi) • Inoculants reduced relative abundance of Enterobacteriaceae in the ARD rhizoplane • Inoculants increased phytoalexin content in roots, stronger in grass than ARD soil.

Enhancing intercropping sustainability: Manipulating soybean rhizosphere microbiome through cropping patterns

Understanding the responses of soybean rhizosphere and functional microbiomes in intercropping scenarios holds promise for optimizing nitrogen utilization in legume-based intercropping systems. This study investigated three cropping layouts under film mulching: sole soybean (S), soybean–maize intercropping in one row (IS), and soybean–maize intercropping in two rows (IIS), each subjected to two nitrogen levels: 110 kg N ha−1 (N110) and 180 kg N ha−1 (N180). Our findings reveal that cropping patterns alter bacterial and nifh communities, with approximately 5 % of soybean rhizosphere bacterial amplicon sequence variants (ASVs) and 42 % of rhizosphere nifh ASVs exhibiting altered abundances (termed sensitive ASVs). Root traits and soil properties shape these communities, with root traits exerting greater influence. Sensitive ASVs drive microbial co-occurrence networks and deterministic processes, predicting 85 % of yield variance and 78 % of partial factor productivity of nitrogen, respectively. These alterations impact bacterial and nifh diversity, complexity, stability, and deterministic processes in legume-based intercropping systems, enhancing performance in terms of yield, nitrogen utilization efficiency, land equivalent ratio, root nodule count, and nodule dry weight under IIS patterns with N110 compared to other treatments. Our findings underscore the importance of field management practices in shaping rhizosphere-sensitive ASVs, thereby altering microbial functions and ultimately impacting the productivity of legume-based intercropping systems. This mechanistic understanding of soybean rhizosphere microbial responses to intercropping patterns offers insights for sustainable intercropping enhancements through microbial manipulation.

The rhizosphere and root selections intensify fungi-bacteria interaction in abiotic stress-resistant plants.

The microbial communities, inhabiting around and in plant roots, are largely influenced by the compartment effect, and in turn, promote the growth and stress resistance of the plant. However, how soil microbes are selected to the rhizosphere, and further into the roots is still not well understood. Here, we profiled the fungal, bacterial communities and their interactions in the bulk soils, rhizosphere soils and roots of eleven stress-resistant plant species after six months of growth. The results showed that the root selection (from the rhizosphere soils to the roots) was stronger than the rhizosphere selection (from the bulk soils to the rhizosphere soils) in: (1) filtering stricter on the fungal (28.5% to 40.1%) and bacterial (48.9% to 68.1%) amplicon sequence variants (ASVs), (2) depleting more shared fungal (290 to 56) and bacterial (691 to 2) ASVs measured by relative abundance, and (3) increasing the significant fungi-bacteria crosskingdom correlations (142 to 110). In addition, the root selection, but not the rhizosphere selection, significantly increased the fungi to bacteria ratios (f:b) of the observed species and shannon diversity index, indicating unbalanced effects to the fungal and bacteria communities exerted by the root selection. Based on the results of network analysis, the unbalanced root selection effects were associated with increased numbers of negative interaction (140 to 99) and crosskingdom interaction (123 to 92), suggesting the root selection intensifies the negative fungi-bacteria interactions in the roots. Our findings provide insights into the complexity of crosskingdom interactions and improve the understanding of microbiome assembly in the rhizosphere and roots.

Core bacteria and fungi in response to residue retention and their contribution to soil multifunctionality in maize agroecosystem

Core microbiome has been proven to play crucial roles in soil function. However, we still lack knowledge on how core microbiome responds to crop residue retention, and whether they contribute to this process. Consequently, we examined the effect of residue retention on soil core and non-core microbial communities in maize seedling, mature stage and freezing period based on a multi-site field experiment in Sanjiang Plain, Northeast China. Totally, 247 bacterial amplicon sequence variants (ASVs) and 109 fungal ASVs were identified as core microbiota. Both core and non-core bacterial/fungal community composition were significantly influenced by residue retention across all study sites. Especially, the core fungal community shifted towards a saprotroph-dominated community. Normalized stochastic ratio pattern revealed that that deterministic process dominated both core and non-core microbial community assembly processes. Residue retention enhanced the deterministic process of core microbial community assembly, while exhibited opposite effect on non-core microbial community. This study also revealed that soil fungi were more sensitive to residue retention than bacteria, with a larger proportion of core fungi were enriched or depleted by residue retention. In addition, residue retention complicated core bacterial co-occurrence network, while simplified fungal network. Our results pointed out both no reduction in microbial diversity or collapse in microbial network structure after repeated freezing-thawing cycles. The potential function of core microbiome was evaluated through random forest analysis and structural equation model, the results indicated core microbiome contributed more to multifunctionality than non-core microbiome. Overall, this study strengthened our understanding of soil core microbiome in response to residue retention, and highlighted their importance in maintaining soil multifunctionality.

Premature Infant Gut Microbiome relationships with childhood behavioral scales: preliminary insights.

Very Low Birth Weight (VLBW) infants, born weighing less than 1,500 grams, are at risk for both gut dysbiosis and later neuropsychological developmental deficits. Behavioral effects, while related to neurodevelopment, are often more subtle and difficult to measure. The extent of later neurobehavioral consequences associated with such microbial dysbiosis has yet to be determined. We explored associations between the infants' gut microbiome and early childhood behavior at 4 years of age and identified the bacterial taxa through a multivariate analysis by linear models. Parents completed the Child Behavior Checklist (CBCL) focused on different DSM diagnostic categories: affective, anxiety, pervasive developmental, attention deficit/hyperactivity, and oppositional defiant. All the CBCL scores were corrected for gender, delivery method, gestational age, infant birth weight, occurrence of sepsis, and days on antibiotics prior statistical analyses. Canonical correlation analysis (CCA) was performed to determine the relationship between early life gut microbiome and the adjusted CBCL scores. The association of bacterial Amplicon sequence Variants (ASVs) to the CBCL scores were tested with multivariate analysis by linear models (MaAsLin). Nineteen children who were previously born with very low birth weight and studied while hospitalized in the Neonatal Intensive Care Unit (NICU) were included in this study. Statistically significant associations were observed between early life gut bacteria such as Veillonella dispar, Enterococcus, Escherichia coli, and Rumincococcus to later behavior at 4 years. No significant association could be observed with early-life gut microbiome alpha diversity and behavioral measures at 4 years. These preliminary observational data provide insight into the relationships between VLBW gut microbiome dysbiosis and childhood behavior. This study contributes to the literature on gut microbiome analysis by examining various behavioral domains using a standardized tool linked to the Diagnostic and Statistical Manual of Mental Disorders (DSM).

Diet and monensin influence the temporal dynamics of the rumen microbiome in stocker and finishing cattle

BackgroundStocker cattle diet and management influence beef cattle performance during the finishing stage, but knowledge of the dynamics of the rumen microbiome associated with the host are lacking. A longitudinal study was conducted to determine how the feeding strategy from the stocker to the finishing stages of production affects the temporal dynamics of rumen microbiota. During the stocker phase, either dry hay or wheat pasture were provided, and three levels of monensin were administrated. All calves were then transported to a feedlot and received similar finishing diets with or without monensin. Rumen microbial samples were collected on d 0, 28, 85 during the stocker stage (S0, S28 and S85) and d 0, 14, 28, 56, 30 d before slaughter and the end of the trial during the finishing stage (F0, F14, F28, F56, Pre-Ba, and Final). The V4 region of the bacterial 16S rRNA gene of 263 rumen samples was sequenced.ResultsHigher alpha diversity, including the number of observed bacterial features and the Shannon index, was observed in the stocker phase compared to the finishing phase. The bacterial amplicon sequence variants (ASVs) differentiating different sampling time points were identified. Dietary treatments during the stocker stage temporally impact the dynamics of rumen microbiota. For example, shared bacteria, including Bacteroidales (ASV19) and Streptococcus infantarius (ASV94), were significantly higher in hay rumen on S28, S85, and F0, while Bacteroidaceae (ASV11) and Limivicinus (ASV15) were more abundant in wheat. Monensin affected rumen microbial composition at a specific time. Transportation to feedlot significantly influenced microbiome structure and diversity in hay-fed calves. Bacterial taxa associated with body weight were classified, and core microbiotas interacted with each other during the trial.ConclusionsIn summary, the temporal dynamics of the rumen microbiome in cattle at the stocker and finishing stage are influenced by multiple factors of the feeding strategy. Diet at the stocker phase may temporarily affect the microbial composition during this stage. Modulating the rumen microbiome in the steers at the stocker stage affects the microbial interactions and performance in the finishing stage.

Comparative analysis of the intestinal microbiota of black-necked cranes (Grus nigricollis) in different wintering areas.

Fecal microbiota is essential for host health because it increases digestive effectiveness. The crane species Grus nigricollis (G. nigricollis) is considered to be near threatened. The fecal microbial composition of crane is less understood, particularly in the Tibet, China. This study was performed to investigate the differences in fecal microbial composition and diversity of crane in different wintering areas using third-generation single-molecule real-time sequencing technology in the Tibet, China. According to the findings, 20 samples were used to generate 936 bacterial amplicon sequence variants (ASVs) and 1,800 fungal ASVs, only 4 bacterial ASVs and 20 fungal ASVs were shared in four distinct locations. Firmicutes were the dominant bacterial phylum in all samples, and Ascomycota and Basidiomycota were the dominant fungal phylum. At the genus level, Lactobacillus was the dominant genus in Linzhi City (LZ), Shannan City (SN), and Lasa City (LS), whereas Megamonas was the dominant genus in Rikaze City (RKZ). Naganishia and Mycosphaerella were the dominant fungal genera in SN and RKZ. Mycosphaerella and Tausonia were the dominant fungal genera in LZ. Naganishia and Fusarium were the dominant fungal genera in LS. And the fecal microbial composition varied between the four groups, as shown by the underweighted pair-group method with arithmetic means and principal coordinates analysis. This study offers a theoretical basis for understanding the fecal microbial composition of crane.

Microbiome Responses to Oral Fecal Microbiota Transplantation in a Cohort of Domestic Dogs.

Fecal microbiota transplants (FMTs) have been successful at treating digestive and skin conditions in dogs. The degree to which the microbiome is impacted by FMT in a cohort of dogs has not been thoroughly investigated. Using 16S rRNA gene sequencing, we document the changes in the microbiome of fifty-four dogs that took capsules of lyophilized fecal material for their chronic diarrhea, vomiting, or constipation. We found that the relative abundances of five bacterial genera (Butyricicoccus, Faecalibacterium, Fusobacterium, Megamonas, and Sutterella) were higher after FMT than before FMT. Fecal microbiome alpha- and beta-diversity were correlated with kibble and raw food consumption, and prior antibiotic use. On average, 18% of the stool donor's bacterial amplicon sequence variants (ASVs) engrafted in the FMT recipient, with certain bacterial taxa like Bacteroides spp., Fusobacterium spp., and Lachnoclostridium spp. engrafting more frequently than others. Lastly, analyses indicated that the degree of overlap between the donor bacteria and the community of microbes already established in the FMT recipient likely impacts engraftment. Collectively, our work provides further insight into the microbiome and engraftment dynamics of dogs before and after taking oral FMTs.

Urbanization reduces gut bacterial microbiome diversity in a specialist ground beetle, Carabus convexus.

Urbanization is rapidly shaping and transforming natural environments, creating networks of modified land types. These urbanization-driven modifications lead to local extinctions of several species, but the surviving ones also face numerous novel selection pressures, including exposure to pollutants, habitat alteration, and shifts in food availability and diversity. Based on the assumption that the environmental pool of microorganisms is reduced in urban habitats due to habitat alteration, biodiversity loss, and pollution, we hypothesized that the diversity of bacterial microbiome in digestive tracts of arthropods would be lower in urban than rural habitats. Investigating the gut bacterial communities of a specialist ground beetle, Carabus convexus, in forested rural versus urban habitats by next generation high-throughput sequencing of the bacterial 16S rRNA gene, we identified 3839 bacterial amplicon sequence variants. The composition of gut bacterial samples did not significantly differ by habitat (rural vs. urban), sex (female vs. male), sampling date (early vs. late spring), or their interaction. The microbiome diversity (evaluated by the Rényi diversity function), however, was higher in rural than urban adults. Our findings demonstrate that urbanization significantly reduced the diversity of the gut bacterial microbiome in C. convexus.

Seeding and feeding milestones: the role of human milk microbes and oligosaccharides in the temporal development of infant gut microbiota

Abstract Breastfeeding represents a strong selective factor for shaping the infant gut microbiota. Besides providing nutritional requirements for the infant, human milk is a key source of oligosaccharides, human milk oligosaccharides (HMOs), and diverse microbes in early life. This study aimed to evaluate the influence of human milk microbiota and oligosaccharides on the composition of infant faecal microbiota at one, three, and nine months postpartum. We profiled milk microbiota, HMOs, and infant faecal microbiota from 23 mother–infant pairs at these time points. The predominant genera in milk samples were Streptococcus, Staphylococcus, and an unclassified Enterobacteriaceae genus-level taxon (Enterobacteriaceae uncl.), whereas the infant faecal microbiota was predominated by Bifidobacterium, Bacteroides, and Enterobacteriaceae uncl. Mother–infant dyads frequently shared bacterial amplicon sequence variants (ASVs) belonging to the genera Bifidobacterium, Streptococcus, Enterobacteriaceae uncl., Veillonella, Bacteroides, and Haemophilus. The individual HMO concentrations in the milk showed either no change or decreased over the lactation period, except for 3-fucosyllactose (3-FL), which increased. Neither maternal secretor status nor HMO concentrations were significantly associated with microbiota composition at the different ages or the bacterial ASVs of maternal milk and infant faeces. This study suggests an age-dependent role of milk microbes in shaping the gut microbiota, while variations in HMO concentrations show limited influence.

Cultivar-specific dynamics: unravelling rhizosphere microbiome responses to water deficit stress in potato cultivars

BackgroundGrowing evidence suggests that soil microbes can improve plant fitness under drought. However, in potato, the world’s most important non-cereal crop, the role of the rhizosphere microbiome under drought has been poorly studied. Using a cultivation independent metabarcoding approach, we examined the rhizosphere microbiome of two potato cultivars with different drought tolerance as a function of water regime (continuous versus reduced watering) and manipulation of soil microbial diversity (i.e., natural (NSM), vs. disturbed (DSM) soil microbiome).ResultsWater regime and soil pre-treatment showed a significant interaction with bacterial community composition of the sensitive (HERBST) but not the resistant cultivar (MONI). Overall, MONI had a moderate response to the treatments and its rhizosphere selected Rhizobiales under reduced watering in NSM soil, whereas Bradyrhizobium, Ammoniphilus, Symbiobacterium and unclassified Hydrogenedensaceae in DSM soil. In contrast, HERBST response to the treatments was more pronounced. Notably, in NSM soil treated with reduced watering, the root endophytic fungus Falciphora and many Actinobacteriota members (Streptomyces, Glycomyces, Marmoricola, Aeromicrobium, Mycobacterium and others) were largely represented. However, DSM soil treatment resulted in no fungal taxa and fewer enrichment of these Actinobacteriota under reduced watering. Moreover, the number of bacterial core amplicon sequence variants (core ASVs) was more consistent in MONI regardless of soil pre-treatment and water regimes as opposed to HERBST, in which a marked reduction of core ASVs was observed in DSM soil.ConclusionsBesides the influence of soil conditions, our results indicate a strong cultivar-dependent relationship between the rhizosphere microbiome of potato cultivars and their capacity to respond to perturbations such as reduced soil moisture. Our study highlights the importance of integrating soil conditions and plant genetic variability as key factors in future breeding programs aiming to develop drought resistance in a major food crop like potato. Elucidating the molecular mechanisms how plants recruit microbes from soil which help to mitigate plant stress and to identify key microbial taxa, which harbour the respective traits might therefore be an important topic for future research.

Effects of tillage practices on soil organic carbon, microbial community and necromass in a double rice cropping system

No-tillage (NT) can enhance the accumulation of soil organic carbon (SOC), thereby aiding in climate change mitigation and improving soil fertility. However, the relations of soil microbial abundance, composition, and necromass to SOC increase under NT are still unclear, limiting the knowledge of SOC stabilization. We performed a 5-year paddy field experiment in southern China including NT, reduced tillage (RT) and conventional tillage (CT). Soil microbial necromass C (MC, including fungal and bacterial necromass C, FC, and BC) were analyzed, as well as soil bacterial and fungal community composition. At a depth of 0–10 cm, NT increased FC (by 48.6 %–50.2 %, P < 0.05), BC (28.6 %–41.7 %), and MC (38.5 %–45.1 %, P < 0.05) but did not significantly alter the FC/BC and MC/SOC ratios. The increase rate of MC (NT vs. CT and RT) was 12.8–16.2 % higher than that of total SOC. Compared with 0–10 cm and 10–20 cm, the MC/SOC ratio was 12.5 %–14.1 % lower at 20–30 cm. Linear regression indicated significant positive correlations of SOC with MC, BC, and FC, whereas no significant correlation was found between bacterial (or fungal) α-diversity (expressed by Shannon index) and BC (or FC). The Random Forest Model showed that several important fungal and bacterial Amplicon Sequence Variants (ASVs) explained 14 %–73 % of the FC and BC variations. Therefore, the composition of the microbial community may play a pivotal role in driving the accumulation of MC. Short-term NT in rice paddies resulted in increased levels of both MC and SOC. Notably, the rate of increase in MC exceeded that of SOC, suggesting the potential for SOC stabilization.

Exploiting the microbiome associated with normal and abnormal sprouting rice (Oryza sativa L.) seed phenotypes through a metabarcoding approach

Rice germination and seedlings’ growth are crucial stages that influence crop establishment and productivity. These performances depend on several factors, including the abundance and diversity of seed microbial endophytes. Two popular rainfed rice varieties cultivated in Cameroon, NERICA 3 and NERICA 8, were used for investigating the seed-associated microbiome using the Illumina-based 16 S rRNA gene. Significant differences were observed in terms of richness index between normal and abnormal seedlings developed from sprouting seeds, although no significant species evenness index was assessed within either phenotype. Two hundred ninety-two bacterial amplicon sequence variants were identified in seed microbiome of the rice varieties, and principal coordinate analysis revealed that microbial communities formed two distinct clusters in normal and abnormal seedling phenotypes. Overall, 38 bacteria genera were identified, belonging to 6 main phyla. Furthermore, the core microbiome was defined, and the differential abundance of 28 bacteria genera was assessed. Based on the collected results, putative bacterial genera were directly correlated with the development of normal seedlings. For most genera that are recognised to include beneficial species, such as Brevundimonas, Sphingomonas, Exiguobacterium, Luteibacter, Microbacterium and Streptomyces, a significant increase of their relative abundance was found in normal seedlings. Additionally, in abnormal seedlings, we also observed an increased abundance of the genera Kosakonia and Paenibacillus, which might have controversial aspects (beneficial or pathogenic), together with the presence of some genera (Clostridium sensu stricto) that are commonly correlated to sick plants. The putative functional gene annotation revealed the higher abundance of genes related to the metabolic biosynthesis of soluble carbohydrates and starch, tryptophan, nucleotides and ABC transporters in normal seedlings. Data presented in this study may help in further understanding the importance of the seed endophyte microbiome for driving a correct development of rice plants at the early stages and to identify possible beneficial bacteria for technological applications aimed to increase seed quality and crop productivity.

Subtle Responses of Soil Bacterial Communities to Corn-Soybean-Wheat Rotation

Crop rotational diversity can improve crop productivity and soil health, and boost soil microbial diversity. This research hypothesized that a 3-year rotation of corn-soybean-wheat (CSW), compared with a 2-year corn-soybean (CS) rotation, would result in a more diverse and more complex soil bacterial community, together with a greater abundance of beneficial bacteria. This was evaluated in a replicated experiment established in 2013 at two locations in Ohio (United States). The soil bacterial communities under soybean were compared between CS and CSW at both studied sites in 2018 and 2019, through 16S ribosomal DNA amplicon metabarcoding. Experimental site was the main driver of bacterial richness and evenness. Significant effects on bacterial community composition were observed in response to the interaction between site, rotational sequence, and year of study. Eight bacterial amplicon sequence variants were identified within all CSW treatments and were not present in CS. Several taxa were differentially abundant between rotation treatments, including the genera Ralstonia being more abundant in CS. Co-occurrence networks, including hub taxa, were generally different between rotation treatments and year, with more structure observed in CSW networks for one of the studied sites. Few bacterial genera were consistently identified as hubs across all networks, including an unidentified member of order Acidobacteriales, while other hubs were unique for CSW networks, including members of the family Gemmatimonadaceae. Finally, the composition of the bacterial communities at the northwestern site positively correlated with plant biomass and active carbon, whereas more recalcitrant pools (total carbon and organic water) correlated with the bacterial communities at the western site.

Metagenomic Analysis of the Composition of Microbial Consortia Involved in Spruce Degradation over Time in Białowieża Natural Forest.

Deadwood plays an important role in forest ecology; its degradation and, therefore, carbon assimilation is carried out by fungi and bacteria. To quantify the abundance and distribution of microbial taxa inhabiting dead spruce logs fallen over a span of 50 years and the soil beneath, we used taxonomic profiling with NGS sequencing of hypervariable DNA fragments of ITS1 and 16S V3-V4, respectively. The analysis of sequencing data revealed a high level of diversity in microbial communities participating in the degradation of spruce logs. Differences in the relative abundance of microbial taxa between the samples of the wood that died in 1974 and 2014, and of the soil in its immediate vicinity, were visible, especially at the genus level. Based on the Lefse analysis significantly higher numbers of classified bacterial taxa were observed in the wood and soil samples from 2014 (wood: 1974-18 and 2014-28 taxa; soil: 1974-8 and 2014-41 taxa) while the number of classified fungal taxa was significantly higher in the wood and soil samples from 1974 (wood: 1974-17 and 2014-9 taxa; soil: 1974-57 and 2014-28 taxa). Most of the bacterial and fungal amplicon sequence variants (ASVs) unique to wood were found in the samples from 1974, while those unique to soil were detected in the samples from 2014. The ATR-FTIR method supported by CHN analysis revealed physicochemical changes in deadwood induced by the activity of fungal and bacterial organisms.

Multi-breed host rumen epithelium transcriptome and microbiome associations and their relationship with beef cattle feed efficiency

Understanding host-microbial interactions in the rumen and its influence on desirable production traits may lead to potential microbiota manipulation or genetic selection for improved cattle feed efficiency. This study investigated the host transcriptome and its correlation with the rumen archaea and bacteria differential abundance of two pure beef cattle breeds (Angus and Charolais) and one composite beef hybrid (Kinsella) divergent for residual feed intake (RFI; low-RFI vs. high-RFI). Using RNA-Sequencing of rumen tissue and 16S rRNA gene amplicon sequencing, differentially expressed genes (FDR ≤ 0.05, |log2(Fold-change) >|2) and differentially abundant (p-value < 0.05) archaea and bacteria amplicon sequence variants (ASV) were determined. Significant correlations between gene expression and ASVs (p-value < 0.05) were determine using Spearman correlation. Interesting associations with muscle contraction and the modulation of the immune system were observed for the genes correlated with bacterial ASVs. Potential functional candidate genes for feed efficiency status were identified for Angus (CCL17, CCR3, and CXCL10), Charolais (KCNK9, GGT1 and IL6), and Kinsella breed (ESR2). The results obtained here provide more insights regarding the applicability of target host and rumen microbial traits for the selection and breeding of more feed efficient beef cattle.