Pathogen profile of Baiyangdian Lake sediments using metagenomic analysis and their correlation with environmental factors

Study on the growth and decline patterns and environmental drivers of pathogens during the stabilization process of simulated landfilling municipal solid waste

Waste and leachate in landfills are substantial reservoirs of pathogens, however information about the risk of pathogen contamination during the stabilization process under different landfill conditions is very limited. In this study, dynamic changes of culturable pathogens, bacteria community, and human bacterial pathogens (HBPs) during the stabilization process under different landfill conditions were investigated, and the environmental drivers were explored. Results showed that total coliforms, Enterococcus, and Staphylococcus aureus were the dominant pathogens detected in waste and leachate samples. During the landfill stabilization process, the concentration of culturable pathogens peaked at the hydrolysis-acidification stage (3.6 × 105 CFU·g-1) in the anaerobic condition, fluctuated from 4.18 × 104 to 5.35 × 105 CFU·g-1 in the anaerobic leachate-recirculation condition, and kept rising (from 4.18 × 104 to 2.12 × 106 CFU·g-1) in the micro-aerobic condition. Moreover, HBPs abundance and diversity in the waste and leachate under micro-aerobic conditions were higher than those under the other two conditions, suggesting a higher risk of pathogen contamination. Sulfate and pH were significantly (p < 0.05) correlated with the composition of bacterial communities and HBPs, likely serving as the major environmental driving factors. Additionally, the interactions between HBPs and functional bacterial groups tended towards cooperative symbiotic relationships, with hydrolytic-acidogenic bacteria promoting the growth and proliferation of most pathogens. These findings will help to understand the changes and environmental drivers of pathogens during landfill stabilization, which will provide a theoretical basis for the risk prevention and control of pathogens in waste disposal.

Effect of bacteriocin RSQ01 on milk microbiota during pasteurized milk preservation

Milk has high risk for microbial contamination. RSQ01, a bacteriocin, previously has shown potentiality for pasteurized milk preservation. This study analyzed the effects of RSQ01 on milk microbiota by comparison of bacterial number and composition in 3 pasteurized milk groups: controls without RSQ01, treatment group with the addition of 2 × MIC (low concentration) and 4 × MIC RSQ01 (high concentration). Integrated 16S rDNA sequencing and metagenomics of these groups after 3 d of storage showed inhibition of RSQ01 on microbiota diversity. Pathogenic bacteria such as Salmonella showed a decrease in relative abundance after RSQ01 treatment, while probiotic bacteria such as Lactococcus showed an increase, indicating that RSQ01 contributed to milk preservation by maintaining a low abundance of pathogens and a relatively high abundance of probiotics. Further investigations revealed that milk preservation was primarily attributed to the ability of RSQ01 to decrease the relative abundance of genes related to metabolism of energy and nutrients (e.g., vitamins, lipids, and amino acids) of microbiota, with change of genetic, environmental, and cellular processes. Interestingly, RSQ01 generally reduced the relative abundance of virulence factors- and quorum-sensing-related genes in microbiota, likely reducing virulence and resistance. The findings provided insights into microbiomics mechanisms regarding pasteurized milk preservation of bacteriocins.

Long-term rice-eel co-culture system effectively alleviated the accumulation of antibiotic resistance genes in soil

Alleviating the accumulation of antibiotic resistance genes (ARGs) in farmlands is crucial for restricting the transfer of ARGs to crops and controlling the soil-borne microbiological health risk. Rice and eel co-culture (REC) systems have recently been used as an emerging integrated farming model that can stabilize grain yields and improve fertilizer availability. However, the influence of long-term REC system concerning the aggregation and health risk of ARGs in rice fields is still unclear. Here, we deciphered firstly the profile, potential of pathogenicity and mobility, and bacterial hosts for soil ARGs in the long-term REC system compared to the mono-rice (MR) culture system by collecting soil samples from 12 rice fields in Shanghai. The long-term REC system alleviated the accumulation of ARGs in soil, which is manifested in the abundance decrease of total ARGs and 11 ARG types (e.g., multidrug and aminoglycoside). The frequency of ARGs co-occurring with VFGs and MGEs was lower in the long-term REC system than in the MR system, indicating the lower pathogenicity and mobility potential for ARGs. The soil microbial community was identified to primarily drive the ARG discrepancy between the long-term REC and MR systems. In comparison with the MR system, long-term REC weakened the competitive advantage of ARG bacterial hosts, which might contribute to the decreased prevalence of antibiotic resistance. Overall, these findings uncovered the important role of long-term REC system in alleviating the accumulation of soil ARGs, providing theoretical support for antibiotic resistance risk control and sustainable agricultural strategic management.

The microbiome alterations of supragingival plaque among adolescents using clear aligners: a metagenomic sequencing analysis

BACKGROUND

White spot lesions (WSLs) may develop in adolescents undergoing clear aligner (CA) therapy with poor oral hygiene. The specific effects of CAs on the microbial composition and functional characteristics of supragingival plaques remain unclear. The present study investigated the shift in the supragingival microbial community induced by CAs in adolescents through metagenomic technology.

METHODS

Fifteen adolescents (12-15 years old) with Invisalign appliances were recruited. Supragingival plaque specimens were obtained twice, before treatment (T1) and three months after treatment (T2). All the bacterial plaque specimens were analyzed for microbial communities and functions using metagenomic analyses.

RESULTS

A total of 2,840,242,722 reads disclosed 180 phyla, 3,975 genera, and 16,497 microbiome species. During the first three months, the microbial community was relatively stable. The genus level revealed a higher relative abundance of Capnocytophaga, Neisseria, and Arachnia in the T2 period. Furthermore, the functional analysis suggested that the relative abundances of folate biosynthesis, biotin metabolism and biofilm formation-vibrio cholerae were increased in the T2 period compared to the T1 period. Finally, virulence factor analysis demonstrated that the relative abundance of genes associated with type IV pili (VF0082) and polar flagella (VF0473) was higher in the T2 period than in the T1 period.

CONCLUSION

In adolescents undergoing CA therapy with poor plaque control, caries progresses quickly within three months and noticeable WSLs develop on the tooth surface. Although the microbial community remained relatively steady and CA therapy did not cause significant changes in the overall functional gene composition in the first three months, virulence factors, including type IV pili and flagella, were more abundant and actively contributed to microorganism adhesion and biofilm formation.

Accumulation and ecological risk assessment of diazinon in surface sediments of Baiyangdian lake and its potential impact on probiotics and pathogens

Diazinon is an organophosphorus pesticide widely used in agriculture and household pest control, and its use also poses several environmental and health hazards. In this study, we investigated the spatial and temporal distribution of diazinon in Baiyangdian, evaluated its potential ecological risk and toxicity to aquatic organisms based on RQ (Risk quotient) and TU (Toxic unit) analysis, and assessed the potential effects of diazinon accumulation on probiotics and pathogens based on statistical analysis of high-throughput sequencing data. The results showed that diazinon in Baiyangdian posed a low to moderate chronic risk to sediment-dwelling organisms and a low toxicity effect on aquatic invertebrates, which was mainly concentrated in October and human-intensive areas. Meanwhile, increases in sediment electrical conductivity (EC), amorphous iron oxides content and phenol oxidase activity favored diazinon accumulation in sediments, whereas the opposite was the case for sediment organic carbon, β-1,4-glucosidase, phosphatase, catalase and pH, suggesting that environmental indicators play a key role in the behavior and distribution of diazinon. In addition, diazinon in heavily contaminated areas seem to inhibit the rare probiotics (Bifidobacterium adolescentis and Serratia sp.), while promoted dominant pathogens (e.g., Burkholderia cenocepacia), which can lead to increased disease risk to humans and ecosystems, disruption of ecological balance and potential health problems. However, probiotic Streptomyces xiamenensis resist to diazinon would be a potential degrader for diazinon remove. In conclusion, this study unveiled the effects of diazinon pollution on wetland ecosystems, emphasizing ecological impacts and potential health concerns. In addition, the discovery of diazinon resistant probiotics provided new insights into wetland ecological restoration.

High-throughput profiling of antibiotic resistance genes in the Yellow River of Henan Province, China

Profiling antibiotic resistance genes (ARGs) in the Yellow River of China's Henan Province is essential for understanding the health risks of antibiotic resistance. The profiling of ARGs was investigated using high-throughput qPCR from water samples in seven representative regions of the Yellow River. The absolute and relative abundances of ARGs and moble genetic elements (MGEs) were higher in summer than in winter (ANOVA, p < 0.001). The diversity and abundance of ARGs were higher in the Yellow River samples from PY and KF than the other sites. Temperature (r = 0.470 ~ 0.805, p < 0.05) and precipitation (r = 0.492 ~ 0.815, p < 0.05) positively influenced the ARGs, while pH had a negative effect (r = - 0.462 ~ - 0.849, p < 0.05). Network analysis indicated that the pathogenic bacteria Rahnella, Bacillus, and Shewanella were the possible hub hosts of ARGs, and tnpA1 was the potential MGE hub. These findings provide insights into the factors influencing ARG dynamics and the complex interaction among the MGEs, pathogenic bacteria and environmental parameters in enriching ARGs in the Yellow River of Henan Province.

Distribution of organophosphorus pesticides and its potential connection with probiotics in sediments of a shallow freshwater lake

Despite the serious health threats due to wide use of organophosphorus pesticides (OPPs) have been experimentally claimed to be remediated by probiotic microorganisms in various food and organism models, the interactions between OPPs and probiotics in the natural wetland ecosystem was rarely investigated. This study delves into the spatial and temporal distribution, contamination levels of OPPs in the Baiyangdian region, the diversity of probiotic communities in varying environmental contexts, and the potential connection with OPPs on these probiotics. In typical shallow lake wetland ecosystem-Baiyangdian lake in north China, eight OPPs were identified in the lake sediments, even though their detection rates were generally low. Malathion exhibited the highest average content among these pesticides (9.51 ng/g), followed by fenitrothion (6.70 ng/g). Conversely, chlorpyrifos had the lowest detection rate at only 2.14%. The region near Nanliu Zhuang (F10), significantly influenced by human activities, displayed the highest concentration of total OPPs (136.82 ng/g). A total of 145 probiotic species spanning 78 genera were identified in Baiyangdian sediments. Our analysis underscores the relations of environmental factors such as phosphatase activity, pH, and electrical conductivity (EC) with probiotic community. Notably, several high-abundance probiotics including Pseudomonas chlororaphis, Clostridium sp., Lactobacillus fermentum, and Pseudomonas putida, etc., which were reported to exhibit significant potential for the degradation of OPPs, showed strongly correlations with OPPs in the Baiyangdian lake sediments. The outcomes of this research offer valuable insights into the spatiotemporal dynamics of OPPs in natural large lake wetland and the probability of their in-situ residue bioremediation through the phosphatase pathway mediated by probiotic such as Lactic acid bacteria in soils/sediments contaminated with OPPs.