Characteristics Of Bacterial Communities Research Articles

Comparison of the Effects of LDPE and PBAT Film Residues on Soil Microbial Ecology.

The plastic film is extensively applied with limited recycling, leading to the long-run residue accumulation in soil, which offers a distinctive habitat for microorganisms, and creates a plastisphere. In this study, traditional low-density polyethylene (LDPE) plastic film and biodegradable polybutylene adipate terephthalate (PBAT) plastic film materials were selected to test their effects on soil microbial ecology. Based on high-throughput sequencing, compared to the soil environment, the alpha-diversity of bacterial communities in plastisphere was lower, and the abundance of Actinobacteria increased. Plastic film residues, as bacterial habitats, exhibited greater heterogeneity and harbor unique bacterial communities. The communities were distinguished between plastisphere and soil environment by means of a random-forest (RF) machine-learning model. Prominent distinctions emerged among bacterial functions between soil environment and plastisphere, especially regarding organics degradation. The neutral model and null model indicated that the constitution of bacterial communities was dominated by random processes except in LDPE plastisphere. The bacterial co-occurrence network of the plastisphere exhibited higher complexity and modularity. This study contributes to our comprehending of characteristics of plastisphere bacterial communities in soil environment and the associated ecological risks of plastic film residues accumulation.

Characteristics of the phyllosphere microbial community and its relationship with major aroma precursors during the tobacco maturation process.

Numerous bacteria, fungi and other microorganisms in the tobacco phyllosphere interstellar area participate in the physiological metabolism of plants by interacting with the host. However, there is currently little research on the characteristics of tobacco phyllosphere microbial communities, and the correlation between tobacco phyllosphere microbial communities and phyllosphere factor indicators is still unknown. Therefore, high-throughput sequencing technology based on the 16S rRNA/ITS1 gene was used to explore the diversity and composition characteristics of tobacco phyllosphere bacterial and fungal communities from different maturation processes, and to identify marker genera that distinguish phyllosphere microbial communities. In this study, the correlations between tobacco phyllosphere bacterial and fungal communities and the precursors of major aroma compounds were explored. The results showed that as the tobacco plants matured, the density of glandular trichomes on the tobacco leaves gradually decreased. The surface physicochemical properties of tobacco leaves also undergo significant changes. In addition, the overall bacterial alpha diversity in the tobacco phyllosphere area increased with maturation, while the overall fungal alpha diversity decreased. The beta diversity of bacteria and fungi in the tobacco phyllosphere area also showed significant differences. Specifically, with later top pruning time, the relative abundances of Acidisoma, Ralstonia, Bradyrhizobium, Alternaria and Talaromyces gradually increased, while the relative abundances of Pseudomonas, Filobassidium, and Tausonia gradually decreased. In the bacterial community, Acidisoma, Ralstonia, Bradyrhizobium, and Alternaria were significantly positively correlated with tobacco aroma precursors, with significant negative correlations with tobacco phyllosphere trichome morphology, while Pseudomonas showed the opposite pattern; In the fungal community, Filobasidium and Tausonia were significantly negatively correlated with tobacco aroma precursors, and significantly positively correlated with tobacco phyllosphere trichome morphology, while Alternaria showed the opposite pattern. In conclusion, the microbiota (bacteria and fungi) and aroma precursors of the tobacco phyllosphere change significantly as tobacco matures. The presence of Acidisoma, Ralstonia, Bradyrhizobium and Alternaria in the phyllosphere microbiota of tobacco may be related to the aroma precursors of tobacco.

Characteristics of Epiphytic Bacterial Community on Submerged Macrophytes in Water Environment Supplemented with Reclaimed Water

Biofilms attached to submerged macrophytes play an important role in improving the water quality of the water environment supplemented with reclaimed water. In order to explore the effects of reclaimed water quality and submerged macrophyte species on the characteristics of an epiphytic bacterial community, different types of submerged macrophytes were selected as research objects in this study. 16S rRNA high-throughput sequencing technology was used on the epiphytic bacteria and the surrounding environmental samples to analyze the bacterial community structure and functional genes. The results showed that approximately 20%-35% of the nitrogen and phosphorus nutrients were absorbed and utilized in the water environment supplemented with reclaimed water. However, the COD, turbidity, and chroma of the downstream water were significantly increased. The bacterial community of the biofilms attached to submerged macrophytes was significantly different from that in the surrounding environment (soil, sediment, and water body) and in the activated sludge that was treated by reclaimed water. In terms of bacterial community diversity, the richness and diversity were significantly lower than those of soil and sediment but higher than those of plankton bacteria in water. In terms of bacterial community composition, dominant genera and corresponding abundances were also different from those of other samples. The main dominant bacterial genera were Sphingomonas, Aeromonas, Pseudomonas, and Acinetobacter, accounting for 7%-40%, respectively. Both macrophyte species and the quality of reclaimed water (BOD5, TN, NH4+-N, and TP) could affect the bacterial community. However, the effect of water quality of the bacterial community was greater than that of macrophytes species. Additionally, the quality of reclaimed water also affected the abundance of functional genes in the bacterial community, and the relative abundance of nitrogen and phosphorus cycling functional genes was higher in areas with higher nitrogen and phosphorus concentrations.

Temporal variation in quality characteristics of nutritional constituents and bacterial community during dry salt-fermentation of hilsa (Tenualosa ilisha)

Nutritional constituents and bacterial community of hilsa (Tenualosa ilisha) at different stages of dry salt-fermentation; namely, F1 (after 2 days of salting), F2 (after 5 days of salting) and F3 (ripe product after 15 days of salting) was studied. Dry salt-fermentation did not negatively affect proximate biochemical composition. Total protein content in F1, F2 and F3 was 10.14, 22.30 and 16.21 mg/ml, respectively. With progression of ripening process, protein solubility gradually decreased. In all stages, about 98% protein digestibility was found. TBARS (Thiobarbituric acid reactive substances) values at F1, F2 and F3 stages was 0.30, 0.41 and 0.95 mg MDA/kg, respectively and within acceptable limit. A total of 3,248 OTUs were found. Of the identified 48 phyla, Proteobacteria (66%), Firmicutes (18%) and Bacteroidota (11%) were abundant at F1 stage but Firmicutes (82%) and Proteobacteria (9%) were dominant at F3 stage. Significant differences in the microbial β-diversity among initial, interim and ripe product were observed. There was no significant α-diversity difference at individual stages of dry salt-fermentation of hilsa. Functional gene profile revealed that, in the final product microbial genes related to organismal systems replaced human disease related genes found in initial and interim product. These findings provide new clues for in-depth characterization of salt-fermented foods from viewpoint of food chemistry and microbiology.Graphical

Characteristics of Bacterial Communities under Different Tree Species and Their Response to Soil Physicochemical Properties

This study investigates the structure of soil bacterial communities in the brown mountain soils beneath the deciduous broadleaf forests of Dongling Mountain and their response to soil physicochemical properties. Aiming to provide a scientific basis for soil conservation and sustainable forest development under deciduous broadleaf forests, this research utilized high-throughput sequencing technology to examine the diversity and community structure of bacteria in soil under different tree species, alongside assessing soil physicochemical properties. The results revealed significant differences in nutrient content between the 0–20 cm and 20–40 cm soil layers. Additionally, the N:P in the brown mountain soils of Dongling Mountain was found to be below the national average, indicating potential nitrogen limitation. Dominant bacterial phylum included Actinobacteria, Proteobacteria, and Acidobacteria. The study also found that soil bacterial community structure was similar under different tree species at the same depth but varied significantly with soil depth. Furthermore, redundancy analysis (RDA) showed that the available potassium (AK), total nitrogen (TN), and ammonium nitrogen (NH4+-N) significantly influenced the structural changes in the soil bacterial community. This research highlights the characteristics of soil bacterial community structure beneath deciduous broadleaf forests and its relationship with soil physicochemical properties, offering valuable insights for regional soil ecosystem conservation and forest management.

Environmental factors and particle size shape the community structure of airborne total and pathogenic bacteria in a university campus.

Given the dense population on university campuses, indoor and outdoor airborne bacterial contamination may lead to the rapid spread of diseases in a university environment. However, there are few studies of the characteristics of airborne and pathogenic bacterial communities in different sites on a university campus. In this study, we collected particulate matter samples from indoor and outdoor locations at a university in Bengbu City, Anhui Province, China, and analyzed the community characteristics of airborne and pathogenic bacteria using a high-throughput sequencing technique. The results showed that the composition of the dominant airborne and pathogenic bacterial communities was consistent among sites at the phylum and genus levels, with differences in their relative abundance. There were significant differences in the structure of the airborne and pathogenic bacterial communities between indoor and outdoor sites (p < 0.05). An analysis of similarities (ANOSIM) indicated that the structure of airborne bacterial communities in indoor sites was influenced by the room occupancy rate, ventilation conditions, and the extent of indoor furnishing (p < 0.05), while the structure of pathogenic bacterial communities was influenced by the number of individuals and spatial dimensions (p < 0.05). The impact of particle size on the structure of airborne and pathogenic bacterial communities was relatively minor. A total of 194 suspected pathogenic bacterial species were identified, accounting for 0.0001-1.3923% of the total airborne bacteria, all of which were conditional pathogens. Among them, Saccharopolyspora rectivirgula, Acinetobacter johnsonii, and Moraxella osloensis exhibited relatively high relative abundance, accounting for 24.40, 16.22, and 8.66% of the total pathogenic bacteria, respectively. Moreover, 18 emerging or re-emerging pathogenic bacterial species with significant implications for human health were identified, although their relative abundance was relatively low (0.5098%). The relative abundance of pathogenic bacteria in indoor environments was significantly higher than outdoors, with the laboratory and dormitory having the highest levels. The findings of this study provide valuable guidance for the prevention and control of airborne bacterial contamination and the associated health risks in both a campus environment and other public spaces with high occupancy rates.

Colloidal Filterable Bacteria Enhance Ammonia Nitrogen Enrichment in River Colloids under Different Turbidity Conditions: Bacterial Diversity, Assembly Mechanism, and Nitrogen Transformation

Turbidity has been one of the most typical problems in urban rivers, accompanied by eutrophication. Though the colloid is a nonnegligible factor associated with turbidity and nutrient enrichment in urban rivers, the characteristics of nitrogen enrichment and bacterial communities of colloids under different turbidity conditions of urban rivers have not been well understood. In this study, colloids of low and high molecular weights (LMW, 30 kDa–0.2 μm, and HMW, 0.2–1 μm) were separately collected from the bulk water (&lt;1 μm) of several typical urban rivers in China. Since the colloidal concentration presented the significantly highest correlation with turbidity, colloidal characteristics were further explored under three turbidity gradients with two cutoffs of 10 and 30 NTU. Results showed that colloidal organic matter in medium and high turbidity rivers was mainly sourced from the release of endogenous plankton and the proportion of colloidal organic carbon in dissolved organic carbon increased from 33% to 38% with increased turbidity. Colloidal ammonia nitrogen in medium turbidity accounted for the highest proportion (an average of 60%) in bulk water, which could be explained by the significantly positive correlation of colloidal ester groups and ammonia nitrogen (R2 = 0.47). Bulk water, HMW, and LMW colloids presented different dominant bacterial genera and LMW colloids also contained three unique dominant filterable genera: Flavobacterium, Acinetobacter, and Limnohabitans. LMW colloidal filterable bacteria under medium and high turbidities presented the greatest potential for dissimilatory nitrate reduction to ammonium, which might further enhance the enrichment of ammonia nitrogen in colloids. This study provides a primary understanding of the characteristics of colloids and colloidal bacterial communities in urban rivers from the perspective of turbidity and puts a new insight on the remediation of rivers under medium turbidity.

Characteristics of DOM and bacterial community in rural black and odorous water bodies under different dimensions

Analysis of dissolved organic matter (DOM) composition and microbial characteristics is crucial for tracing the sources of rural black and odorous water bodies (BOWB). The aim of this study was to explore the DOM and microbial diversity and identify the primary environmental factors in BOWB from various pollution sources during different periods using EEMs-PARAFAC and Illumina sequencing. It was found that the physicochemical properties vary widely across different pollution types of BOWB, with higher overall content during the high-water period compared to the normal-water period. The types of dissolved organic matter in BOWB are Tyrosine proteins, Fulvic acid, Dissolved microbial metabolites, and Humic acid. During the normal-water period, DOM originates primarily from terrestrial sources in various water bodies. However, DOM affected by livestock and poultry waste and industrial effluents is influenced by both internal and external sources during periods of high water levels. In industrial waste-type BOWB, the biological sources of water are weak. Proteobacteria, Actinobacteria, Chloroflexi, Firmicutes were the dominant bacterial phyla. According to the redundancy analysis, pH (p = 0.047), Total nitrogen (TN) (p = 0.045), Organic carbon (OC) (p = 0.044), and Nickel (Ni) (p = 0.047) are the primary environmental factors influencing the composition of bacterial communities.

Comparative analysis on root exudate and rhizosphere soil bacterial assembly between tomatoes and peppers infected by Ralstonia

BackgroundThe rhizosphere environment regulated by root secretory activity and rhizosphere microbial interactions plays an essential role in resisting soil-borne diseases, while the host species is an important factor that affects the composition of root exudates and rhizosphere microbiomes. However, few studies have been done on the characteristics of root exudates and bacterial communities in terms of composition, diversity, and functional potential when host plants of different species are subjected to the same disease.ResultsIn this study, we examined the rhizosphere soil bacteria and root exudates of both healthy and diseased tomatoes and peppers employing metabolomics and amplicon techniques. Our findings indicated that variations existed in both root exudates and the bacterial community among different host species and health states. The diversities of both rhizosphere metabolites and bacterial communities were significantly reduced in different diseased plants. Although pepper and tomato resisted the invasion of Ralstonia by recruiting different potentially beneficial bacteria, their rhizosphere bacterial communities had the same functional potential. In comparison to diseased rhizosphere soil, healthy rhizosphere soil had many more functional pathways associated with disease suppression and plant growth.ConclusionsThis study highlighted the crucial role of host plants in shaping the rhizosphere environment and revealed the variation characteristics of root exudates and rhizosphere bacteria of different host plants induced by the same disease.Graphical

Bacterial diversity and functional characteristics of natural rainwater lakes in Saihanba artificial forest farm as revealed by 16S rRNA sequencing

The Saihanba Mechanical Forest is an artificial national forest park with a forest-steppe landscape. The flora and fauna have been extensively studied, but a comprehensive understanding of the bacterial community composition and structure of the natural rainwater lakes present in the area has rarely been reported. In this study, the structure and functional characteristics of bacterial communities in lake sediments and water samples in the Saihanba artificial forest were investigated using 16s rRNA high-throughput sequencing. Microbial diversity analyses revealed that Proteobacteria, Acidobacteria, Bacteroidota and Verrucomicrobiota microbiota dominated. The abundance of Proteobacteria and Actinobacteriota was significantly higher (p < .05) in water samples compared to sediment samples. PICRUSt2 functional analysis predicted genes associated with the degradation of xenobiotics and the execution of essential metabolic processes. Here, we report differences in the composition of native bacterial communities in sediments and water under the Saihanba artificial forest and make functional gene predictions. This study provides a reference for further exploring the structure and functional characteristics of microbial communities in water samples and sediment environments of lakes under planted forests.

Characteristics of bacterial communities in rhizosphere and bulk soil in Fe-deficient citrus growing in coastal saline-alkali land.

Citruses often occur with imbalance in iron nutrition in coastal saline-alkali lands, which severely limits the yield and quality of the fruit. In the rhizosphere, the salt content plays a crucial role in reducing uptake of iron, as well as the activity and abundance of bacteria. However, few studies have explored how salt content affects the effectiveness of iron and the community structure of bacteria across different vertical spatial scales. We investigated the citrus rhizosphere (0-30 cm) and bulk (0-60 cm) soil microenvironments of the coastal saline soil were analyzed using the 16S rRNA amplicon and inductively coupled plasma-optical emission spectroscopy. We found that the nutrient-related elements in the rhizosphere and bulk soil decreased with increasing soil depth, while the salinity-related elements showed the opposite trend. The nutrient-related element content in the rhizosphere was higher than that in the bulk, whereas the salinity-alkaline-related element content was lower than that in the bulk. The structure and diversity of bacterial communities are affected by the rhizosphere and soil depth. In the bulk, there are enriched bacteria such as WB1-A12, Nitrospiraceae and Anaerolineae that are tolerant to salt-alkali stress. In the rhizosphere, bacteria that promote plant nutrient absorption and secretion of iron carriers, such as Pseudomonas, Streptomyces, and Duganella, are prominent. The soil depth and rhizosphere affect soil nutrients and saline alkali-related factors. Changes in soil depth and rhizosphere determine the structure and diversity of bacterial communities. Rhizosphere enhances iron absorption promoting bacteria to alleviate iron deficiency stress in saline-alkali soils. Our results indicate that citrus roots maybe can resist the stress of iron deficiency in saline-alkali soils by enhancing iron absorption promoting bacteria.

Green Waste Compost Impacts Microbial Functions Related to Carbohydrate Use and Active Dispersal in Plant Pathogen-Infested Soil

The effects of compost on physical and chemical characteristics of soil are well-studied but impacts on soil microbiomes are poorly understood. This research tested effects of green waste compost on bacterial communities in soil infested with the plant pathogen Fusarium oxysporum. Compost was added to pathogen-infested soil and maintained in mesocosms in a greenhouse experiment and replicated growth chamber experiments. Bacteria and F. oxysporum abundance were quantified using quantitative PCR. Taxonomic and functional characteristics of bacterial communities were measured using shotgun metagenome sequencing. Compost significantly increased bacterial abundance 8 weeks after amendment in one experiment. Compost increased concentrations of chemical characteristics of soil, including phosphorus, potassium, organic matter, and pH. In all experiments, compost significantly reduced abundance of F. oxysporum and altered the taxonomic composition of soil bacterial communities. Sixteen bacterial genera were significantly increased from compost in every experiment, potentially playing a role in pathogen suppression. In all experiments, there was a consistent negative effect of compost on functions related to carbohydrate use and a positive effect on bacteria with flagella. Results from this work demonstrate that compost can reduce the abundance of soilborne plant pathogens and raise questions about the role of microbes in plant pathogen suppression.

Characteristics of bacterial community in eyelashes of patients with Demodex blepharitis

BackgroundDemodex blepharitis (DB) is a common disease of the ocular surface. The characteristics of the bacterial community in eyelash roots after Demodex infestation are still unknown. Knowledge of the characteristics of the bacterial community of eyelash follicles in patients with DB can provide valuable insights for guiding the diagnosis and treatment of DB.MethodsTwenty-five patients with DB (DB group) and 21 non-DB volunteers (control group) were enrolled in the study. Eyelashes from the upper eyelid of the right eye were sampled, and 16S ribosomal DNA (rDNA) sequencing was performed to determine the V3-V4 regions of the microbial 16S rDNA gene within 1 month of infestation. The sequencing data of the two groups were analyzed and compared. The effect of the bacterium Burkholderia on the survival of Demodex mites was evaluated using Demodex obtained from 12 patients with DB other that the patients in the DB group.ResultsA total of 31 phyla and 862 genera were identified in the DB and control groups. The five most abundant phyla in the two groups were Proteobacteria, Firmicutes, Actinobacteria, Bacteroidetes and Cyanobacteria. The abundance of Actinomycetes was significantly higher in the DB group than in the control group. At the genus level, the five most abundant genera in the two groups were Pseudomonas, Burkholderia-Caballeronia-Paraburkholderia, Rolstonia and Acinetobacter; Clostridium sensu stricto 1 was abundant in the control group and Corynebacterium_1 was abundant in the DB group. Compared with the control group, the abundance of Burkholderia-Caballeronia-Paraburkholderia was 2.36-fold lower in the DB group. Linear discriminant analysis Effect Size (LEfSe) analysis revealed Burkholderia-Caballeronia-Paraburkholderia, SC_I_84_unclassified, Nonmyxobacteria and Succinvibrio to be the major biomarkers in the control group and Catenibacterium and Lachnospiraceae NK4A136 group to be the major biomarkers in the DB group. To explore the performance of these optimal marker models, receiver operational characteristic curve analysis was performed, and the average area under the curve value of Burkholderia-Caballeronia-Paraburkholderia was 0.7448. Burkholderia cepacia isolated from normal human eyelashes was fermented, and the Demodex mites isolated from patient eyelashes were cultured together with its fermented supernatant. The results showed that the fermentation supernatant could significantly reduce the survival time of the Demodex mites, suggesting the potential therapeutic value of this bacterium against Demodex.ConclusionsThe composition of the bacterial community in the eyelashes of DB patients differed from that in eyelashes of healthy volunteers, revealing a decrease in bacterial diversity in infested eyelashes. This decrease may be related to the occurrence and development of DB. The supernatant of Burkholderia cepacia culture medium was found to inhibit the growth of Demodex in eyelash hair follicles, providing a new insight with potential applications for the clinical treatment of Demodex infestation.Graphical

Characteristics of bacterial community and volatile fatty acids in the gastrointestinal tract of Tarim wapiti

Tarim wapiti (Cervus elaphus yarkandensis) may have a complex gut microbiota that contributes to its unique qualities due to its biological characteristics of tolerance to coarse feed and salt-alkali. The contents of the forestomach (rumen, reticulum, and omasum), abomasum, and small intestine (duodenum, jejunum and ileum) were taken in this investigation from six Tarim wapiti. The objective was to assess the content of volatile fatty acids (VFAs) and microbiological diversity through 16S rDNA. The results showed that acetate, propionate, butyrate, and valerate concentrations were much higher in the forestomach compared to the small intestine. The communities of bacteria were abundant and diversified in the forestomach and abomasum compared to the small intestine. Bacteroidetes were significantly more abundant in the forestomach and abomasum than in the small intestine, but Firmicutes were the reverse. The predominant bacterial genera identified in the forestomach and abomasum were Rikenellaceae RC9 gut group, Prevotella and F082; Clostridium sensu stricto 1, Acetitomaculum, Paeniclostridium, and Romboutsia were the main bacterial genera in the small intestine. The relative abundance of genes for microbial energy metabolism functions was substantially reduced across the rumen to the reticulum, across the abomasum to the duodenum for carbohydrate metabolism and lipid metabolism functions, and across the jejunum to the ileum for lipid metabolism and energy metabolism functions. In addition, VFAs were found to be positively correlated with dominant bacteria in forestomach and abomasum, and negatively correlated with dominant bacteria in small intestine. According to the study, Tarim wapiti have developed a unique and distinct dominant bacterial community in its forestomach, abomasum, and intestines.

An Assessment of Human Opportunistic Pathogenic Bacteria on Daily Necessities in Nanjing City during Plum Rain Season.

The plum rain season is a special climatic phenomenon in east Asia, which is characterized by persistent rainfall, a high temperature, and humidity, providing suitable environmental conditions for certain pathogenic bacteria, thus increasing the incidence of respiratory, gastrointestinal, and urinary diseases. However, studies on human opportunistic pathogenic bacteria communities during the plum rain season are still limited. In this study, the characteristics of human opportunistic pathogenic bacterial communities on daily necessities during the non-plum and plum rain seasons were investigated using high-throughput sequencing technology. The results revealed that the relative abundance of human opportunistic pathogenic bacteria was higher in the plum rain season (cotton cloth: 2.469%, electric bicycles: 0.724%, rice: 3.737%, and washbasins: 5.005%) than in the non-plum rain season (cotton cloth: 1.425%, electric bicycles: 0.601%, rice: 2.426%, and washbasins: 4.801%). Both temperature and relative humidity affected human opportunistic pathogenic bacterial communities. Stochastic processes dominated the assembly process of human opportunistic pathogenic bacterial communities, and undominated processes prevailed. The stability of the co-occurrence network was higher in the non-plum rain season than that in the plum rain season. In addition, the proportion of deterministic processes showed the same trend as the complexity of the co-occurrence network.

Seasonal Changes in the Soil Microbial Community Structure in Urban Forests.

Urban forests play a crucial role in the overall health and stability of urban ecosystems. Soil microorganisms are vital to the functioning of urban forest ecosystems as they facilitate material cycling and contribute to environmental stability. This study utilized high-throughput sequencing technology to examine the structural characteristics of bacterial and fungal communities in the bulk soil of six different forest stands: Phyllostachys pubescens (ZL), Metasequoia glyptostroboides (SSL), Cornus officinalis (SZY), mixed broad-leaved shrub forest (ZKG), mixed pine and cypress forest (SBL), and mixed broad-leaved tree forest (ZKQ). Soil samples were collected from each forest stand, including the corners, center, and edges of each plot, and a combined sample was created from the first five samples. The results revealed that among the bacterial communities, ZKG exhibited the highest alpha diversity in spring, while ZL demonstrated the highest alpha diversity in both summer and autumn. Proteobacteria was the most abundant bacterial phylum in all six forest stand soils. The dominant fungal phylum across the six forest stands was identified as Ascomycota. Notably, the microbial community diversity of SBL bulk soil exhibited significant seasonal changes. Although ZL exhibited lower bacterial community diversity in spring, its fungal community diversity was the highest. The bulk soil microbial diversity of ZL and SSL surpassed that of the other forest stands, suggesting their importance in maintaining the stability of the urban forest ecosystem in the Zhuyu Bay Scenic Area. Furthermore, the diversity of the bulk soil microbial communities was higher in all six stands during spring compared to summer and autumn. Overall, this study provides valuable insights into the seasonal variations of bulk soil microbial communities in urban forests and identifies dominant tree species, offering guidance for tree species' selection and preservation in urban forest management.

Impact of soil inorganic nitrogen on bacterial phylogeny in estuarine intertidal zones: a study of nitrogen metabolism.

Here we investigated the potential impacts of soil inorganic nitrogen (SIN) content on the phylogenetic characteristics and ecological functions of soil bacterial communities in estuarine intertidal zones in China, aiming to comprehend the response mechanism of soil microorganisms to variations in SIN content within estuarine wetlands. Our results show that SIN in estuarine areas has a significant spatiotemporal variation on spatial and seasonal scales, in this study and is significantly associated with the phylogenetic diversity and phylogenetic turnover of soil bacterial communities. In addition, the results of the metagenomic analysis showed that the relative abundance of nitrogen-cycling functional genes in bacterial communities did not differ significantly in sampling sites and seasons, and weakly correlated with SIN content. Further, the results based on structural equation modeling (SEM) analysis showed that SIN directly and significantly regulated the phylogenetic characteristics of bacterial communities, thereby indirectly affecting the potential of bacterial nitrogen metabolism. This study emphasizes the key influence of SIN variations on the phylogenetic dissimilarity in soil bacterial communities. Moreover, although there was a weak direct relationship between the functional characteristics of the bacterial nitrogen metabolism and SIN content, the spatiotemporal variation of bacterial nitrogen metabolic potential may be indirectly regulated by SIN content by influencing the phylogenetic diversity in bacterial communities. Our study unravels the pivotal mechanisms through which SIN content influences bacterial communities, thereby offering novel insights into the microbial intricacies governing nitrogen metabolism within estuaries.

Characteristics of bacterial community and extracellular enzymes in response to atrazine application in black soil

The ecological functioning of black soil largely depends on the activities of various groups of microorganisms. However, little is known about how atrazine, a widely used herbicide with known harmful effects on the environment, influences the microbial ecology of black soil, and the extracellular enzymes related to the carbon, nitrogen and phosphorus cycles. Here, we evaluated the change in extracellular enzymes and bacterial community characteristics in black soil after exposure to various concentrations of atrazine. Low concentrations of applied atrazine (10 – 20 mg kg−1) were almost completely degraded after 120 days. At high concentrations (80 – 100 mg kg−1), about 95% of the applied atrazine was degraded over the same period. Additionally, linear fitting of data indicated that the total enzymatic activity index (TEI) and bacterial α-diversity index were negatively correlated with atrazine applied concentration. The atrazine had a greater effect on bacterial beta diversity after 120 days, which differentiated species clusters treated with low and high atrazine concentrations. Soil bacterial community structure and function were affected by atrazine, especially at high atrazine concentrations (80 – 100 mg kg−1). Key microorganisms such as Sphingomonas and Nocardioides were identified as biomarkers for atrazine dissipation. Functional prediction indicated that most metabolic pathways might be involved in atrazine dissipation. Overall, the findings enhance our understanding of the factors driving atrazine degradation in black soil and supports the use of biomarkers as indicators of atrazine dissipation.

Characteristics of gut bacterial microbiota of black soldier fly (Diptera: Stratiomyidae) larvae effected by typical antibiotics

As agents in an emerging technology, Hermetia illucens (Linnaeus, 1758) (Diptera: Stratiomyidae) larvae, black soldier fly, have shown exciting potential for degrading antibiotics in organic solid waste, a process for which gut microorganisms play an important role. This study investigated the characteristics of larval gut bacterial communities effected by typical antibiotics. Initially, antibiotics significantly reduced the diversity of gut bacterial species. After 8 days, diversity recovered to similar to that of the control group in the chlortetracycline, tylosin, and sulfamethoxazole groups. Proteobacteria, Firmicutes, and Actinobacteriota were the dominant phyla at the initial BSFL gut. However, after 4 days treatment, the proportion of Actinobacteriota significantly decreased, but Bacteroidota notably increased. During the conversion process, 18, 18, 17, 21, and 19 core genera were present in the chlortetracycline, sulfamethoxazole, tylosin, norfloxacin, and gentamicin groups, respectively. Pseudomonas, Actinomyces, Morganella, Providencia and Klebsiella might be the important genera with extraordinary resistance and degradation to antibiotics. Statistical analyses of COGs showed that antibiotics changed the microbial community functions of BSFL gut. Compared with the control group, (i) the chlortetracycline, sulfamethoxazole, and tylosin groups showed significant increase in the classification functions of transcription, RNA processing and modification，and so on, (ii) the norfloxacin and gentamicin groups showed significant increase in defense mechanisms and other functions. Note that we categorized the response mechanisms of these classification functions to antibiotics into resistance and degradation. This provides a new perspective to deeply understand the joint biodegradation behavior of antibiotics in environments, and serves as an important reference for further development and utilization of microorganisms-assisted larvae for efficient degradation of antibiotics.

Toxic effects of the heavy metal Cd on Apis cerana cerana (Hymenoptera: Apidae): Oxidative stress, immune disorders and disturbance of gut microbiota

Cadmium (Cd) is a toxic non-essential metal element that can enter the honey bee body through air, water and soil. Currently, there is a lack of sufficient research on the effects of Cd on A. cerana cerana, especially the potential risks of long-term exposure to sublethal concentrations. In order to ascertain the toxicological effects of the heavy metal Cd on bees, we performed laboratory-based toxicity experiments on worker bees and conducted analyses from three distinctive facets: antioxidative, immunological, and gut microbiota. The results showed that exposure of bees to high concentrations of Cd resulted in acute mortality, and the increase in mortality was concentration dependent. In long-term exposure to sublethal concentrations, Cd reduced the number of transcripts of antioxidant genes (AccSOD1, AccTPx3 and AccTPx4) and superoxide dismutase activity, causing an increase in malondialdehyde content. Simultaneously, the transcription of immune-related genes (AccAbaecin and AccApidaecin) and acetylcholinesterase activities was inhibited. Furthermore, Cd changes the structural characteristics of bacterial and fungal communities in the gut, disrupting the balance of microbial communities. In conclusion, the health and survival of honey bees are affected by Cd. This study provides a scientific basis for investigating the toxicological mechanisms and control strategies of the heavy metal Cd on honey bees, while facilitating a better understanding and protection of these valuable honey bees.