Yak rumen fluid inoculum increases biogas production from sheep manure substrate

Microbial inoculant accelerated pig slurry maturation at low-temperature anaerobic digestion: Performance and mechanism

This study investigated the impact of microbial inoculants on maturing pig slurry during anaerobic digestion (AD) at psychrophilic temperatures (10 °C). A simulation experiment was conducted with two treatments: pig slurry alone (CK) and pig slurry supplemented with microbial inoculants (MA). The MA treatment achieved faster maturity than CK, as evidenced by an improved germination index (achieving 70 % in advance) and a reduced content of organic pollutants, which was attributed to an increased relative abundance of hydrolytic microorganisms (7-21 %) and decreased pathogens (6-9 %) at the early stage (<42 (d)). Microbial inoculants influenced pig slurry microorganisms by serving as keystone taxa (B_OTU229 (f_Ruminococcaceae) and F_OTU76 (s_Acremonium alcalophilum)), and stimulating new keystone taxa (B_OTU423 (g_NK4A214) and F_OTU25 (g_Clavulina)) through associative interactions, thereby intensifying saprotrophic and carbon cycling processes, and accelerating maturation. These results provide a biological strategy for maturing pig slurry and help elucidate the mechanisms underlying microbial effects.

Anaerobic co-biodegradation of polyhydroxyalkanoate and swine manure for volatile fatty acid production: The impact of C/N ratios and microbial dynamics

Polyhydroxyalkanoate (PHA) is the important biodegradable plastic, however, biodegradation of PHA waste in anaerobic environments emits more CH4, a potent greenhouse gas. Bioconversion of PHA waste to useful byproducts - volatile fatty acids (VFAs) is a practical method to upcycle carbon from PHA. In this study, PHA waste was anaerobically co-digested with swine manure (SM) (the typical high nitrogen waste) at different C/N ratios. The results indicate that co-digestion of PHA and SM with a C/N ratio of 32.1 achieved VFA production of 5488 mg COD/L and 0.20 g COD/g VS. No significant differences were found in terms of the highest VFA concentrations between treatments with C/N ratios of 43.4 and 32.1. VFA produciton of 3655 mg COD/L and 0.14 g COD/g VS was achieved at 19 days by adjusting the C/N ratio to 19.2. Four bacteria were identified as dominant microorganisms responsible for converting PHA and SM to VFA.

Comparative Analysis of Gut Microbiomes in Laboratory Chinchillas, Ferrets, and Marmots: Implications for Pathogen Infection Research

Gut microbes play a vital role in the health and disease of animals, especially in relation to pathogen infections. Chinchillas, ferrets, and marmots are commonly used as important laboratory animals for infectious disease research. Here, we studied the bacterial and fungal microbiota and discovered that chinchillas had higher alpha diversity and a higher abundance of bacteria compared to marmots and ferrets by using the metabarcoding of 16S rRNA genes and ITS2, coupled with co-occurrence network analysis. The dominant microbes varied significantly among the three animal species, particularly in the gut mycobiota. In the ferrets, the feces were dominated by yeast such as Rhodotorula and Kurtzmaniella, while in the chinchillas, we found Teunomyces and Penicillium dominating, and Acaulium, Piromyces, and Kernia in the marmots. Nevertheless, the dominant bacterial genera shared some similarities, such as Clostridium and Pseudomonas across the three animal species. However, there were significant differences observed, such as Vagococcus and Ignatzschineria in the ferrets, Acinetobacter and Bacteroides in the chinchillas, and Bacteroides and Cellvibrio in the marmots. Additionally, our differential analysis revealed significant differences in classification levels among the three different animal species, as well as variations in feeding habitats that resulted in distinct contributions from the host microbiome. Therefore, our data are valuable for monitoring and evaluating the impacts of the microbiome, as well as considering potential applications.

Change of core microorganisms and nitrogen conversion pathways in chicken manure composts by different substrates to reduce nitrogen losses

Due to the rapid development of animal husbandry, the associated environmental problems cannot be ignored, with the management of livestock and poultry manure emerging as the most prominent issue. Composting technology has been widely used in livestock and poultry manure management. A deeper understanding of the nitrogen conversion process during composting offers a theoretical foundation for selecting compost substrates. In this study, the effects of sawdust (CK) and spent mushroom compost (T1) as auxiliary materials on nitrogen as well as microbial structure in the composting process when composted with chicken manure were investigated. At the end of composting, the nitrogen loss of T1 was reduced by 17.18% relative to CK. When used as a compost substrate, spent mushroom compost accelerates the succession of microbial communities within the compost pile and alters the core microbial communities within the microbial community. Bacterial genera capable of cellulose degradation (Fibrobacter, Herbinix) are new core microorganisms that influence the assimilation of nitrate reduction during compost maturation. Using spent mushroom compost as a composting substrate increased the enzyme activity of nitrogen assimilation while decreasing the enzyme activity of the denitrification pathway.

Contribution of the bacterial community of poorly fermented oat silage to biogas emissions on the Qinghai Tibetan Plateau

To better utilize poorly fermented oat silage on the Qinghai Tibetan Plateau, 239 samples of this biomass were collected from the plateau temperate zone (PTZ), plateau subboreal zone (PSBZ), and nonplateau climatic zone (NPCZ) in the region and analyzed for microbial community, chemical composition and in vitro gas production. Climatic factors affect the bacterial α-diversity and β-diversity of poorly fermented oat silage, which led to the NPCZ having the highest relative abundance of Lactiplantibacillus plantarum. Furthermore, the gas production analysis showed that the NPCZ had the highest maximum cumulative gas emissions of methane. Through structural equation modeling analysis, environmental factors (solar radiation) affected methane emissions via the regulation of lactate production by L. plantarum. The enrichment of L. plantarum contributes to lactic acid production and thereby enhances methane emission from poorly fermented oat silage. Notably, there are many lactic acid bacteria detrimental to methane production in the PTZ. This knowledge will be helpful in revealing the mechanisms of environmental factors and microbial relationships influencing the metabolic processes of methane production, thereby providing a reference for the clean utilization of other poorly fermented silage.

Microbial Risks Caused by Livestock Excrement: Current Research Status and Prospects

Livestock excrement is a major pollutant yielded from husbandry and it has been constantly imported into various related environments. Livestock excrement comprises a variety of microorganisms including certain units with health risks and these microorganisms are transferred synchronically during the management and utilization processes of livestock excrement. The livestock excrement microbiome is extensively affecting the microbiome of humans and the relevant environments and it could be altered by related environmental factors as well. The zoonotic microorganisms, extremely zoonotic pathogens, and antibiotic-resistant microorganisms are posing threats to human health and environmental safety. In this review, we highlight the main feature of the microbiome of livestock excrement and elucidate the composition and structure of the repertoire of microbes, how these microbes transfer from different spots, and they then affect the microbiomes of related habitants as a whole. Overall, the environmental problems caused by the microbiome of livestock excrement and the potential risks it may cause are summarized from the microbial perspective and the strategies for prediction, prevention, and management are discussed so as to provide a reference for further studies regarding potential microbial risks of livestock excrement microbes.

Bioaugmentation with marine sediment-derived microbial consortia in mesophilic anaerobic digestion for enhancing methane production under ammonium or salinity stress

Ammonium (NH₄⁺) and salinity (NaCl) inhibit CH₄ production in anaerobic digestion. However, whether bioaugmentation using marine sediment-derived microbial consortia can relieve the inhibitory effects of NH₄⁺ and NaCl stresses on CH₄ production remains unclear. Thus, this study evaluated the effectiveness of bioaugmentation using marine sediment-derived microbial consortia in alleviating the inhibition of CH₄ production under NH₄⁺ or NaCl stress and elucidated the underlying mechanisms. Batch anaerobic digestion experiments under 5 gNH₄-N/L or 30 g/L NaCl were performed with or without augmentation using two marine sediment-derived microbial consortia pre-acclimated to high NH₄⁺ and NaCl. Compared with non-bioaugmentation, bioaugmentation reinforced CH₄ production. Network analysis revealed the joint effects of microbial connections by Methanoculleus, which promoted the efficient consumption of propionate accumulated under NH₄⁺ and NaCl stresses. In conclusion, bioaugmentation with pre-acclimated marine sediment-derived microbial consortia can mitigate the inhibition under NH₄⁺ or NaCl stress and enhance CH₄ production in anaerobic digestion.