Bacterial Community Succession Research Articles

Engineered biochar combined clay for microplastic biodegradation during pig manure composting

This study pursued to regulate bacterial community succession pattern and expedited biodegradation of microplastics (MP) during pig manure (PM) composting employing walnut shell biochar (WSB) and montmorillonite (M). The WSB with concentration of 0%, 2.5%, 5%, 7.5%, 10% and 12% along with 10% M participated into PM for 42 days compost to search the optimal solution. The results confirmed the most prosperous bacterial phylum consisted of Firmicutes (3.02%–91.80%), Proteobacteria (2.08%–48.54%), Chloroflexi (0–44.62%) and Bacteroidetes (0.85%–40.93%). The addition of biochar has dramatically arranged bacterial community at different stages of composting. Energy Dispersive Spectrometer (EDS) revealed that carbon element in MPs decreased since the chemical bond fracture, under the intervention of high-temperature composting and WSB, the carbon content of MPs was maximum reduced by 20.25%. Fourier transform infrared spectrum indicated that CC, C–O, C–H and –COOH abundance of MPs in 10% and 12% dose biochar addition sharply reduced, interestingly, explicating WSB and composting made MP biodegradable. This experiment possesses affirmatory practical meaning for elimination of potential hazards by composting.

Compositional and functional succession of soil bacterial communities during long-term rice cultivation on saline-alkali soils: Insights derived from a new perspective of the core bacterial taxa

The conversion of saline-alkali soils into paddy fields for long-term rice cultivation involves multiple disturbances, and as a result, soil microbial communities are altered to adapt to a changing environment. A comprehensive understanding of the succession of soil bacterial communities that occurs during this process, however, is still lacking. In the present study, we utilized data obtained from rice paddies of different cultivation years to investigate the compositional and functional succession of the soil bacterial community. We focused on core bacterial taxa that were specifically enriched at different successional stages. Generalized joint attribute modeling (GJAM) was used to identify core bacterial taxa. Results indicated that bare saline-alkali soils shared few core amplicon sequence variants (ASVs) with paddy fields. Longimicrobiaceae from the phylum Gemmatimonadetes was dominant in bare saline-alkali soils, while their dominance was subsequently replaced by Burkholderiaceae and Pedosphaeraceae, phyla affiliated with the Proteobacteria and Verrucomicrobia, after 5 years and 23 years of rice cultivation, respectively. The abundance of nitrogen metabolism functions in the core bacterial community present in bare saline-alkali soils were higher than they were in other successional stages, while sulfur metabolism functions exhibited the opposite trend. These data indicate that the role of the core bacterial taxa in mediating nutrient cycling also changed and adapted to changing soil conditions as rice cultivation became established. Redundancy analysis (RDA) indicated that the compositions of the core bacterial community in Y0, Y5s, Y10s, and Y20s groups were driven by nitrate-nitrogen content, soil pH, available phosphorus content, and the ratio of total carbon to total nitrogen, respectively. In summary, the present study provides insights into the succession of soil bacterial communities and core bacterial taxa that occur during long-term rice cultivation.

Microplastics exert minor influence on bacterial community succession during the aging of earthworm (Lumbricus terrestris) casts

The soil microbiome, which is shaped by gut-related activities of earthworms, is affected by microplastic contamination. However, the influence of microplastics on earthworm gut and cast microbiomes has been poorly explored. Here, we investigated the influence of microplastics (1% in soil, w/w) on soil physicochemical properties and bacterial communities during gut passage and cast aging of Lumbricus terrestris. Microplastics used in agricultural film production were selected, i.e., low density polyethylene, polylactic acid and polybutylene adipate terephthalate (PBAT). Different niches, including pre-ingestion soil, gut content and aged casts (from 0 to 180 days), were studied. Results showed that microplastics possibly enhanced the gut passage-derived difference between pre-ingestion soil and fresh cast in terms of pH, ammonium, nitrate and nitrite, and dissolved organic carbon. But such effects mostly faded out after 180 days of aging. The composition, as well as the alpha and beta diversity of both the total (DNA) and active (RNA) bacterial communities were decisively shaped by their niche (R2: 0.22–0.63, p < 0.001, PERMANOVA), rather than the presence/absence or the types of MPs. Nevertheless, biomarkers indicative of PBAT treatment were identified, and functional prediction for the active community showed that bacterial communities of this treatment had higher potentials for hydrocarbon degradation (4.9–7.8 times that of the microplastic-free treatment in gut and aged casts). We also identified a “Soil-related core community” and a “Gut-related core community” (contributing to 39.2%–50.2% of the cast microbiome), which possibly neutralized microplastic impacts and maintained the structure and function of bacterial communities during the soil–gut–cast transit. Our findings indicate that the tested microplastics exerted a minor influence on the bacterial communities during the cast aging process, microplastics in aged casts might not necessarily have significant additional influence on the soil microbiome when they are incorporated into soils. Future studies testing different soils, polymers, and earthworm species, under field conditions are recommended to help enhance current knowledge of the influence of microplastics on earthworm cast microbiomes.

The potential correlation between the succession of microflora and volatile flavor compounds during the production of Zhenba bacon

Microbial composition plays an important role in the quality and flavor of bacon. The aims of this study were to detect bacterial community succession using high-throughput sequencing (HTS) and volatile flavor compound changes using gas chromatography-ion mobility spectrometry (GC-IMS) during the production of Zhenba bacon. The results showed that a total of 70 volatile compounds were detected. Among them, ketones, hydrocarbons, aldehydes, esters and alcohols were the main substances in the curing and smoking stages. In addition, the fungal abundance was greater than the bacterial abundance, and there was obvious succession of the microbial community with changes in fermentation time and processing technology. The main functional bacterial genera in the curing and smoking stages were Staphylococcus, Psychrobacter and Latilactobacillus, and the main fungal genera were Fusarium and Debaryomyces. Through correlation analysis, we found that pyrrole, 2-pentanol, methyl isobutyl ketone (MIBK) and ethyl acetate (EA) were significantly correlated with Staphylococcus, Psychrobacter, Pseudomonas and Myroides (p < 0.01), and it is speculated that they contribute significantly to flavor formation. The results of this study are helpful for understanding the microbial dynamics and characteristic volatile flavor compounds in Zhenba bacon, and provide new insights into the relationship between microorganisms and flavor through potential correlations.

Fulvic acid and fermentation agent optimize in situ composting by reducing antibiotic resistance genes abundances and altering succession of bacterial communities

The use of biostimulants to enhance microbial activity has been extensively reported. However, their regulatory properties on the ecological security of in situ composting have not yet been fully elucidated. Here, the effects of two biostimulants (fermentation agent [FM] and fulvic acid [FA]) on in situ composting were investigated under field conditions. The abundances of antibiotic resistance genes (ARGs), as well as those of the microbial communities and the activities of enzymes, were comprehensively investigated. The addition of biostimulants significantly reduced the abundances of streptomycin and sulfonamide resistance genes by 79%–97% and decreased the abundance of Gammaproteobacteria. This was particularly true for species that are members of the Enterobacteriaceae and contain many ARGs. The addition of biostimulants promoted the succession of bacterial communities toward enhancing the solubility of phosphorus, promoting the degradation of aromatic compounds, and reducing the emissions of NOx gas. The application of FA and FM resulted in distinct bacterial network structures, and many negative correlations were associated with ARGs in the temperature subnetwork in the FM treatment. This study provides an effective strategy for the in situ treatment of agricultural waste and underscores the significance of biostimulants in improving the biological safety of medium-temperature in-situ composting.

Bacterial assembly and succession patterns in conventional and advanced drinking water systems: From source to tap

Bacteria are pivotal to drinking water treatment and public health. However, the mechanisms of bacterial assembly and their impact on species coexistence remain largely unexplored. This study explored the assembly and succession of bacterial communities in two full-scale drinking water systems over one year. We observed a decline in bacterial biomass, diversity, and co-occurrence network complexity along the treatment processes, except for the biological activated carbon filtration stage. The conventional plant showed higher bacterial diversity than the advanced plant, despite similar bacterial concentrations and better removal efficiency. The biological activated carbon filter exhibited high phylogenetic diversity, indicating enhanced bacterial metabolic functionality for organic matter removal. Chlorination inactivated most bacteria but favored some chlorination-resistant and potentially pathogenic species, such as Burkholderia, Bosea, Brevundimonas, and Acinetobacter. Moreover, the spatiotemporal dynamics of the bacterial continuum were primarily driven by stochastic processes, explaining more than 78% of the relative importance. The advanced plant’s bacterial community was less influenced by dispersal limitation and more by homogeneous selection. The stochastic process regulated bacterial diversity and influenced the complexity of the species co-occurrence network. These findings deepen our understanding of microbial ecological mechanisms and species interactions, offering insights for enhancing hygienic safety in drinking water systems.

Sediment DNA Records the Critical Transition of Bacterial Communities in the Arid Lake

It is necessary to predict the critical transition of lake ecosystems due to their abrupt, non-linear effects on social-economic systems. Given the promising application of paleolimnological archives to tracking the historical changes of lake ecosystems, it is speculated that they can also record the lake’s critical transition. We studied Lake Dali-Nor in the arid region of Inner Mongolia because of the profound shrinking the lake experienced between the 1300 s and the 1600 s. We reconstructed the succession of bacterial communities from a 140-cm-long sediment core at 4-cm intervals and detected the critical transition. Our results showed that the historical trajectory of bacterial communities from the 1200 s to the 2010s was divided into two alternative states: state1 from 1200 to 1300 s and state2 from 1400 to 2010s. Furthermore, in the late 1300 s, the appearance of a tipping point and critical slowing down implied the existence of a critical transition. By using a multi-decadal time series from the sedimentary core, with general Lotka-Volterra model simulations, local stability analysis found that bacterial communities were the most unstable as they approached the critical transition, suggesting that the collapse of stability triggers the community shift from an equilibrium state to another state. Furthermore, the most unstable community harbored the strongest antagonistic and mutualistic interactions, which may imply the detrimental role of interaction strength on community stability. Collectively, our study showed that sediment DNA can be used to detect the critical transition of lake ecosystems.

Recycled by leaf inhabitants: Terrestrial bacteria drive the mineralization of organic matter in lake water

AbstractTerrestrial organic matter subsidizes aquatic food webs and plays an important role in carbon cycling in lake ecosystems, where it is decomposed mainly by microbes. However, the contribution of terrestrial and aquatic microbiomes on terrestrial carbon cycling and their effects on the biochemical fate of carbon has remained understudied. Therefore, we explored the microbial carbon utilization of three chemically differing leaf species in lake water in microcosms and quantified the biochemical endpoints of leaf carbon in CO2, CH4, and microbial biomass. Additionally, we identified microbial taxa responsible for leaf carbon recycling and studied the role of epiphytic and endophytic leaf microbiomes in microbial community succession in lake water. Microbially utilized leaf carbon was mainly respired (82.7 ± 1.4%), whereas a small proportion (17.1 ± 1.4%) was assimilated into biomass. Carbon from nitrogen‐rich alder leaves was taken up at the fastest rate, whereas birch leaf addition produced the highest concentrations of CH4, suggesting that leaf chemistry affects the decomposition rate and biochemical fate of carbon. In particular, terrestrial bacteria shaped the succession of aquatic bacterial communities. The addition of leaves resulted in the equal contribution of epiphytic and endophytic bacteria in the lake water, whereas epiphytic fungi dominated the fungal community structure. Our results suggest that terrestrial bacteria originating from terrestrial leaves influence the microbiome succession in lake ecosystems and play a key role in linking terrestrial carbon to an aquatic food web and determining the quality of carbon emissions that are released into the atmosphere.

Succession of particle-attached and free-living bacterial communities in response to microalgal dynamics induced by the biological cyanocide paucibactin A

Microalgae, including cyanobacteria and eukaryotic algae, are hotspots of primary production and play a critical role in global carbon cycling. However, these species often form blooms that poses a threat to aquatic ecosystems. Although the use of bacteria-derived cyanocides is regarded as an environmentally friendly method for controlling cyanobacterial blooms, only a few studies have examined their potential impact on ecosystems. This study is the first to explore the response of particle-attached (PA) and free-living (FL) bacteria to the dynamics of microalgal communities induced by the biological cyanocide paucibactin A. The microalgal community dynamics were divided into two distinct phases [phase I (days 0–2) and phase II (days 3–7)]. In phase I, paucibactin A caused a sudden decrease in the cyanobacterial concentration. Phase II was characterized by increased growth of eukaryotic microalgae (Scenedesmus, Pediastrum, Selenastrum, and Coelastrum). The stability of the bacterial community and the contribution of stochastic processes to community assembly were more pronounced in phase II than in phase I. The microalgal dynamics triggered by paucibactin A coincided with the succession of the PA and FL bacterial communities. The lysis of cyanobacteria in phase I favored the growth of microbial organic matter degraders in both the PA (e.g., Aeromonas and Rheinheimera) and FL (e.g., Vogesella) bacterial communities. In phase II, Lacibacter, Phycisphaeraceae, and Hydrogenophaga in the PA bacterial community and Lacibacter, Peredibacter, and Prosthecobacter in the FL bacterial community showed increased relative abundances. Overall, the FL bacterial community exhibited greater sensitivity to the two sequential processes compared with the PA bacterial community. These results highlight the need for studies evaluating the impact of biological cyanocides on aquatic ecosystems when used to control natural cyanobacterial blooms.

The Contributions of Sub-Communities to the Assembly Process and Ecological Mechanisms of Bacterial Communities along the Cotton Soil-Root Continuum Niche Gradient.

Soil microbes are crucial in shaping the root-associated microbial communities. In this study, we analyzed the effect of the soil-root niche gradient on the diversity, composition, and assembly of the bacterial community and co-occurrence network of two cotton varieties. The results revealed that the bacterial communities in cotton soil-root compartment niches exhibited a skewed species abundance distribution, dominated by abundant taxa showing a strong spatial specificity. The assembly processes of the rhizosphere bacterial communities were mainly driven by stochastic processes, dominated by the enrichment pattern and supplemented by the depletion pattern to recruit bacteria from the bulk soil, resulting in a more stable bacterial community. The assembly processes of the endosphere bacterial communities were determined by processes dominated by the depletion pattern and supplemented by the enrichment pattern to recruit species from the rhizosphere, resulting in a decrease in the stability and complexity of the community co-occurrence network. The compartment niche shaped the diversity of the bacterial communities, and the cotton variety genotype was an important source of diversity in bacterial communities within the compartment niche. We suggest that the moderate taxa contribute to significantly more changes in the diversity of the bacterial community than the rare and abundant taxa during the succession of bacterial communities in the cotton root-soil continuum.

Improving the bacterial community, flavor, and safety properties of northeastern sauerkraut by inoculating autochthonous Levilactobacillus brevis

The effect of Levilactobacillus brevis as a starter in northeastern sauerkraut fermentation is still unknown, and further evaluation is worthwhile. Hence, this study aimed to evaluate the effect of autochthonous L. brevis inoculation on the bacterial community succession and formation of flavor and harmful substances in sauerkrauts. Inoculation with L. brevis lowered the pH and increased the total acid content of sauerkrauts (P < 0.05). The nitrite content of the inoculated sauerkraut was significantly lower than that of control (P < 0.05). Moreover, the spoilage bacteria of the inoculated sauerkraut were decreased and nitrogen metabolism was improved. The contents of aldehydes, alcohols, esters, acids, and alkanes increased significantly (P < 0.05), and the sensory attributes such as aroma, sourness, and gloss were also improved. L. brevis was positively and negatively correlated with flavor metabolites and nitrite, respectively, which proved to be a potential starter culture to manufacture sauerkraut.

Effects of lactic acid bacteria inoculants on the nutrient composition, fermentation quality, and microbial diversity of whole-plant soybean-corn mixed silage.

The mixture of whole-plant soybean and whole-plant corn silage (WPSCS) is nutrient balanced and is also a promising roughage for ruminants. However, few studies have investigated the changes in bacterial community succession in WPSCS inoculated with homofermentative and heterofermentative lactic acid bacteria (LAB) and whether WPSCS inoculated with LAB can improve fermentation quality by reducing nutrient losses. This study investigated the effect of Lactobacillus plantarum (L. plantarum) or Lactobacillus buchneri (L. buchneri) on the fermentation quality, aerobic stability, and bacterial community of WPSCS. A 40:60 ratio of whole-plant soybean corn was inoculated without (CK) or with L. plantarum (LP), L. buchneri (LB), and a mixture of LP and LB (LPB), and fermented for 14, 28, and 56 days, followed by 7 days of aerobic exposure. The 56-day silage results indicated that the dry matter content of the LP and LB groups reached 37.36 and 36.67%, respectively, which was much greater than that of the CK group (36.05%). The pH values of the LP, LB, and LPB groups were significantly lower than those of the CK group (p < 0.05). The ammoniacal nitrogen content of LB was significantly lower than that of the other three groups (p < 0.05), and the ammoniacal nitrogen content of LP and LPB was significantly lower than that of CK (p < 0.05). The acetic acid content and aerobic stability of the LB group were significantly greater than those of the CK, LP, and LPB groups (p < 0.05). High-throughput sequencing revealed a dominant bacteria shift from Proteobacteria in fresh forage to Firmicutes in silage at the phylum level. Lactobacillus remained the dominant genus in all silage. Linear discriminant analysis effect size (LEFSe) analysis identified Lactobacillus as relatively abundant in LP-treated silage and Weissella in LB-treated groups. The results of KEGG pathway analysis of the 16S rRNA gene of the silage microbial flora showed that the abundance of genes related to amino acid metabolism in the LP, LB, and LPB groups was lower than that in the CK group (p < 0.05). In conclusion, LAB application can improve the fermentation quality and nutritional value of WPSCS by regulating the succession of microbial communities and metabolic pathways during ensiling. Concurrently, the LB inoculant showed the potential to improve the aerobic stability of WPSCS.

Bacterial Community Succession in Earthworm Mucus and Sludge Compost and its Relationship with Environmental Factors

Bacterial Community Succession in Earthworm Mucus and Sludge Compost and its Relationship with Environmental Factors

Effects of thermophilic bacteria inoculation on maturity, gaseous emission and bacterial community succession in hyperthermophilic composting

Hyperthermophilic composting, characterized by temperatures equal to or exceeding 75 °C, offers superior compost maturity and performance. Inoculation with thermophilic bacteria presents a viable approach to achieving hyperthermophilic composting. This study investigates the effects of inoculating thermophilic bacteria, isolated at different temperatures (50 °C, 60 °C, and 70 °C) into compost on maturity, gaseous emissions, and microbial community dynamics during co-composting. Results indicate that the thermophilic bacteria inoculation treatments exhibited peak temperature on Day 3, with the maximum temperature of 75 °C reached two days earlier than the control treatment. Furthermore, these treatments demonstrated increased bacterial richness and diversity, along with elevated relative abundances of Firmicutes and Proteobacteria. They also fostered mutualistic correlations among microbial species, enhancing network connectivity and complexity, thereby facilitating lignocellulose degradation. Specifically, inoculation with thermophilic bacteria at 60 °C increased the relative abundance of Thermobifida and unclassified-f-Thermomonosporaceae (Actinobacteriota), whereas Bacillus, a thermophilic bacterium, was enriched in the 70 °C inoculation treatment. Consequently, the thermophilic bacteria at 60 °C and 70 °C enhanced maturity by 36 %–50 % and reduced NH3 emissions by 1.08 %–27.50 % through the proliferation of thermophilic heterotrophic ammonia-oxidizing bacteria (Corynebacterium). Moreover, all inoculation treatments decreased CH4 emissions by 6 %–27 % through the enrichment of methanotrophic bacteria (Methylococcaceae) and reduced H2S, Me2S, and Me2SS emissions by 1 %–25 %, 47 %–63 %, and 15 %–53 %, respectively. However, the inoculation treatments led to increased N2O emissions through enhanced denitrification, as evidenced by the enrichment of Truepera and Pusillimonas. Overall, thermophilic bacteria inoculation promoted bacteria associated with compost maturity while attenuating the relationship between core bacteria and gaseous emissions during composting.

Succession of bacterial and fungal communities during the mud solarization of salt-making processing in a 1000-year-old marine solar saltern

A 1000-year-old marine solar saltern in Hainan Island, South China, is in the continuation of traditional skills involving mud soak and solarization for three days to accumulate salt, which is a unique process contributing to the selection of highly halophilic microbes related to salt quality and flavor. Herein, the successions of physicochemical properties and bacterial and fungal communities of muds from the saltern were investigated during the processing of mud solarization. The results showed that Na+, Cl−, Mg2+ and total nitrogen were the main factors in explaining the fluctuation of the fungal community, whereas the bacterial community was predominantly determined by Ca2+, total kalium and total phosphorus. During three days of mud solarization, the soil bacterial alpha diversity in the saltern was significantly lower than that of the surroundings, whereas the fungal alpha diversity showed an opposite trend. The bacterial functional groups with the same survival and adaptation strategies remained relatively stable, while the dominant functional type in fungi changed from monotropic to complex trophic mode. Additionally, some unidentified fungi species were increasingly found in mud. The abundances of Saitozyma, Solicoccozyma and Wallemia (Basidiomycota) increased and may contribute to the salt flavor through decomposing cellulose molecules into glucose due to their higher β-glucosidase activity, while the harmful fungal genera including Inocybe and Paraconiothyrium decreased obviously due to the stresses of salinity and solar exposure. These results showed that the traditional salt-making skills associated with mud solarization have selected a high abundance of beneficial halophilic microbes to increase the salt quality and flavor. Our findings not only reveal the underlying mechanisms for the long-history salt-making skills of this 1000-year-old unusual cultural heritage but also are highly valuable for bioprospecting to develop novel halophilic bacteria and fungi for modern chemistry industries.

Effect of Forest Fires on the Alpha and Beta Diversity of Soil Bacteria in Taiga Forests: Proliferation of Rare Species as Successional Pioneers

Forest fires are among the most influential drivers of changes in forest soil bacterial diversity. Nevertheless, little is known regarding the effects of forest fires on maintaining the complex interactions that preserve forest ecosystem stability. Therefore, this study characterized alterations in soil bacterial community composition and diversity within taiga forests subjected to varying disturbance intensities. Particularly, this study examined the bacterial community within a Larix gmelinii fire-burnt site in Daxinganling, analyzing the changes in bacterial community structure and function across light, moderate, and heavy fire-burnt sites, as well as a control sample site, utilizing Illumina MiSeq technology. Through an assessment of bacterial community diversity and soil physicochemical properties (moisture content (MC), pH, microbial biomass carbon (MBC), organic carbon (SOC), total nitrogen (TN), available nitrogen (AN), available phosphorus (AP), and available potassium (AP)), we explored the influence of the soil microenvironment on the soil bacterial community structure at the burnt site under different disturbance intensities. Our findings demonstrated that (1) there was no significant change in the Chao index of soil bacteria in the burnt site under different disturbance intensities, whereas the Shannon index decreased significantly (p &lt; 0.05) and the Simpson index increased significantly (p &lt; 0.05) in the burnt site under light and moderate disturbance. (2) The relative abundance of dominant phyla, such as Proteobacteria, Proteobacteria, and Actinobacteriota, did not change significantly in the fire-burnt site under different disturbance intensities, whereas rare species, such as Acidipila, Occallatibacter, and Acidibacter, experienced a significant increase in relative abundance at the genus level. (3) The results of principal coordinates analysis (PCoA) and canonical correlation analysis (CCA) revealed significant differences in the Beta diversity of soil bacteria in the fire-burnt site under varying interference intensities. The Beta diversity of soil bacteria exhibited significant differences (p = 0.001), with MC, pH, TN, AN, and AK identified as significant influencing factors. (4) FAPROTAX functional prediction analyses were conducted to assess the changes in soil bacteria involved in Cellulolysis, Chemoheterotrophy, and Aerobic_Chemoheterotrophy in the fire-burnt site, with the relative abundance of bacteria involved in Chemoheterotrophy being significantly increased (p &lt; 0.05) under different disturbance intensities. Collectively, our findings demonstrated that different disturbance intensities caused by fires significantly affected the Alpha diversity, Beta diversity, and functional abundance of soil bacterial communities in taiga forests, with MC, pH, TN, AN, and AK being identified as key influencing factors. Additionally, the presence of numerous rare species suggests their role as pioneer communities in the succession of soil bacterial communities.

Effects of different cold chain logistics modes on the quality and bacterial community succession of fresh pork

The connection and temperature control of cold chain links are key to ensuring meat quality. Considering the practical production of cold chain logistics in China, this study investigated the impact of various cold chain logistics modes (including warehousing, transportation, and sales conditions) at different temperature settings (7 °C, 4 °C, and − 1 °C), modeled in the laboratory, on the quality and bacterial community succession of pork. The pork quality was evaluated by pH, water holding capacity, total volatile basic nitrogen (TVB-N), total viable count (TVC) and myowater status. Among the different cold chain logistics modes, the LL1 (samples being warehoused and transported at 4 °C for 96 h and sold at −1 °C) and the SL1 (samples being warehoused and transported at 4 °C for 30 h and sold at −1 °C) modes were suitable for inter-provincial and intra-provincial transportation due to their long shelf life (> 14 days), respectively. The bacterial community succession of pork in different cold chain logistics modes was accessed by high-throughput sequencing. The results indicated that the cold chain logistics modes had affected the bacterial community, with Latilactobacillus being the dominant bacteria in the LL1 mode and SL1 mode during spoilage. The study revealed that the entire or partial process supercooling treatment (−1 °C) during the cold chain logistics process could effectively preserve the meat quality, supporting the high-quality development of the fresh meat cold chain logistics.

Correlation between the bacterial community succession and purine compound changes during Huangjiu fermentation

Purine is mainly culprit of hyperuricemia (HUA) and gout, which is widely present in Huangjiu in the form of free bases. Bacterial succession plays an important role in quality control in Huangjiu. The correlation between the purine compound content and the bacterial communities during the fermentation process has not yet been evaluated. In this study, high-throughput sequencing (HTS) technology was used to monitor the bacterial community composition of Huangjiu at different fermentation stages. The correlation between the bacterial community and the contents of physicochemical properties and purine compounds were evaluated using the Spearman analysis method. The key enzymes of purine metabolism pathway in the microbial community were analyzed by bioinformatics using Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt). The results showed that the purine content in Huangjiu increased gradually in 0∼9d of fermentation (21.05–65.71 mg/L), and stabilized gradually in 12∼18d (65.63–69.55 mg/L), while the abundance of lactic acid bacteria (LAB) of bacterial microbial flora were increased (0∼9d) and then stabilized (12∼18d). Moreover, Lactobacillus acetotolerans and Lactobacillus helveticus were highly correlated positively with purine contents, while Limosilactobacillus fermentum and Lactiplantibacillus plantarum were correlated negatively. In addition, the dominant strains of bacteria were involved in the metabolism of purine, and the key enzymes for purine compound synthesis were more abundant than that for purine degradation. This study is helpful to scientifically understand the formation mechanism of purines, providing a basis for screening functional strains of purine degrading to accurately regulate purine level in Huangjiu.

Synergistic removal of total petroleum hydrocarbons and antibiotic resistance genes in Yellow River Delta wetlands contaminated soil composting regulated by biogas slurry addition

The interactive effects between the emerging contaminant antibiotic resistance genes (ARGs) and the traditional pollutant total petroleum hydrocarbons (TPHs) in contaminated soils remain unclear. The synergistic removal of TPHs and ARGs from composted contaminated soil, along with the microbial mechanisms driven by the addition of biogas slurry, have not yet been investigated. This study explored the impact of biogas slurry on the synergistic degradation mechanisms and bacterial community dynamics of ARGs and TPHs in compost derived from contaminated soil. The addition of biogas slurry resulted in a reduction of targeted ARGs and mobile genetic elements (MGEs) by 9.96%–95.70% and 13.32%–97.66%, respectively. Biogas slurry changed the succession of bacterial communities during composting, thereby reducing the transmission risk of ARGs. Pseudomonas, Cellvibrio, and Devosia were identified as core microorganisms in the synergistic degradation of ARGs and TPHs. According to the partial least squares path model, temperature and NO3− indirectly influenced the removal of ARGs and TPHs by directly regulating the abundance and composition of host microbes and MGEs. In summary, the results of this study contribute to the high-value utilization of biogas slurry and provide methodological support for the low-cost remediation of contaminated soils.

Exploration of the Vermiculite-Induced Bacterial Community and Co-Network Successions during Sludge-Waste Mushroom Co-Composting.

Vermiculite is a clay mineral with unique physical properties that plays a significant role in plant cultivation, soil remediation, and solid waste management. In this research, we first explored how vermiculite-to-microbe interactions evolved during sludge-waste mushroom residue co-composting. Vermiculite's addition had a substantial impact on the microbial α and β diversities, significantly changed the microbial community pattern, and strengthened the composting nutrient circulation through the formation of more specialist and generalist species. The microbial community characteristics exhibited common co-networks for resisting composting environment stresses. Vermiculite contributed to enhancing the keystone taxa Proteobacteria and Actinobacteriota and caused the ecological function network to diversify in the warming and maturation phases, with more complexity and tightness in the thermophilic phase (with super-generalist species existing). The enhanced microbial interactions induced by vermiculite possessed a greater capacity to facilitate the metabolisms of carbohydrates and amino acids and cellulolysis, thereby promoting composting humification, and nitrogen retention in the final compost and composting maturity. These findings are helpful for us to understand the biological process mechanisms of the effect of vermiculite additives on composting and contribute to the establishment of a theoretical framework for enhancing the microbial interactions in composting systems by adding vermiculite in practical applications.