Anaerobic digestion characteristics and key microorganisms associated with low-temperature rapeseed cake and sheep manure fermentation

Abstract

Qinghai rural household biogas digesters were used to evaluate fermentation characteristics, including gas production and key microbial community changes, associated with low-temperature (15.2-17.8℃) mixed rapeseed cake and sheep manure anaerobic fermentations across 40 days using seven different ratios of material. Different raw material ratios resulted in signi cantly different effects on biogas yields and microbial community compositions. When the ratio of sheep manure to rapeseed cake was 1:2, the highest level of cumulative gas production was observed (122.92 m 3 •t −1 ). Firmicutes, Proteobacteria, Bacteroidetes, and Actinobacteria were the dominant bacterial phyla among the 29 digester samples (total relative abundances > 79.23%), followed by Synergistetes (4.09%-10.7%). Lactobacillus was the most abundant genus in the biogas digesters with high rapeseed cake contents (average relative abundances: 14.68%), while Peptoniphilus exhibited higher abundances (12.69%) in the mixed fermentation digester treatments. In addition, unclassi ed Synergistaceae abundances (6.64%) were positively associated with biogas production variation among treatments. Bacteroides (5.74%) and Pseudomonas (5.24%) both accounted for larger proportions of communities in the digesters that used more sheep manure. Methanomicrobiales (66.55%) was the most dominant archaeal group among digesters, with Methanogenium (41.82%) and Methanoculleus (16.55%) representing the main gas-producing archaeal genera; they were more abundant in biogas digesters with higher sheep manure contents and higher rapeseed cake contents, respectively. Regardless of the raw material ratios, Methanoculleus exhibited the highest abundances on the 4th day of fermentation. VFAs and pH were the main factors associated with differences in microbial communities among the 29 samples. Speci cally, VFA concentrations were positively correlated with Lactobacillus and Methanoculleus abundances, while pH was positively correlated with Bacteroides, Pseudomonas, Methanobrevibacter, and Methanobacterium abundances.

Study on anaerobic phosphorus release from pig manure and phosphorus recovery by vivianite method

“…In the control group, Proteobacteria is the dominant flora, accounting for 50.3% of the total flora. Proteobacteria is the largest of the bacteria, which has important metabolic functions in anaerobic digestion 24 . It can use small molecular compounds such as glucose and butyrate to promote the degradation of amino acids and long-chain fatty acids.…”

Rare methanotrophs adapt to broader environmental gradients than abundant methanotrophs in the riparian zone of the Three Gorges Reservoir

“…Determining which variables impact the relative contributions of deterministic and stochastic processes is critical to bettering our understanding of the mechanism of microbial community assembly (Y. Liu & Sheng, 2021; Soto et al, 2022; B. Wu, Luo, et al, 2022; B. Wu, Zhou, et al, 2022). In some studies, environmental parameters, such as dissolved oxygen, temperature, pH, and biochar, as well as nutrients, such as nitrogen and phosphorus, have been shown to influence the structure of abundant and/or rare taxa (R. Liu, Guo, & Steinberger, 2022; L. Liu, Xiong, et al, 2022; Z. Wu et al, 2019). Despite this, little is known about the effects of environmental parameters on the relative contributions of deterministic and stochastic processes in wetland ecosystems and the role of methanotrophic community assembly.…”

“…There may be a connection between this phenomenon and the rapid environmental change caused by specific environmental conditions and human activities (Ren et al, 2018;Tsao et al, 2019), such as fluctuating water levels in riparian zones, leading to nutrient loss. Consequently, rare methanotrophs may have exhibited a high degree of phylogenetic differentiation due to rapid adaptation in the current study, which would have contributed to the OTU richness and Shannon Index values for the rare taxa being higher than for the abundant taxa (R. Liu, Guo, & Steinberger, 2022;L. Liu, Xiong, et al, 2022).…”

“…Wu, Zhou, et al, 2022). In some studies, environmental parameters, such as dissolved oxygen, temperature, pH, and biochar, as well as nutrients, such as nitrogen and phosphorus, have been shown to influence the structure of abundant and/or rare taxa (R. Liu, Guo, & Steinberger, 2022;L. Liu, Xiong, et al, 2022;Z.…”

Manure Application Is the Key to Improving Soil Quality of New Terraces

“…In the MNP treatment, the manure applied each year was equal to that applied to the M treatment, and the mineral N and P fertilizers applied were equal to that applied to the NP treatment. The average nutrient content of the sheep manure applied was: organic carbon (C) 150 g kg −1 , total N 10 g kg −1 , and total P 0.84 g kg −1 ; pH 8.1, electrical conductivity 4.87 dS m −1 [34]; total solids 38.5%, volatile solids 30.1% [35]. The contents of Cr, Cd, Pb, As, and Hg ranged from 3.2 to 40.1, 0.5 to 4.7, 2.4 to 70.8, 0.5 to 4.9, and 0.02 to 2.39 mg kg −1 [36].…”