Electron transfer and microbial mechanism of synergistic degradation of lignocellulose by hydrochar and aerobic fermentation.

In response to the problem of asynchronous fermentation between lignocellulose and perishable materials in compost, the combined technology of low-temperature hydrochar and compost has been studied. Hydrochar was prepared through low-temperature hydrothermal reactions and applied to aerobic fermentation. The response relationship between lignocellulose content, electron transfer capability, and microbes was explored. The results showed that a pore structure with oxygen-containing functional groups was formed in hydrochar, promoting electron transfer during composting. With the rapid increase in composting temperature, the lignocellulose content decreased by 64.36 mg/g. Oceanobacillus, Cerasibacillus, Marinimicrobium, and Gracilibacillus promoted the degradation of lignocellulose and the carbon/nitrogen cycle during aerobic fermentation, and there was a significant response relationship between electron transfer capability and functional microbes. The combined application of hydrochar and aerobic fermentation accelerated the degradation of lignocellulose. This study provides technical support for the treatment of heterogeneous organic waste.

Halomonas zhaodongensis sp. nov., a slightly halophilic bacterium isolated from saline-alkaline soils in Zhaodong, China.

A slightly halophilic bacterium (strain NEAU-ST10-25(T)) was isolated from saline-alkaline soils in Zhaodong City, Heilongjiang Province, China. The strain is a Gram-negative, aerobic motile rod. It accumulates poly-ß-hydroxyalkanoate and produces exopolysaccharide. It produces beige-yellow colonies. Growth occurs at NaCl concentrations (w/v) of 0-15 % (optimum 3 %), at temperatures of 4-60 °C (optimum 35 °C) and at pH 6-12 (optimum pH 9). Its G+C content is 53.8 mol%. Phylogenetic analyses based on the separate 16S rRNA gene and concatenation of the 16S rRNA, gyrB and rpoD genes indicate that it belongs to the genus Halomonas in the class Gammaproteobacteria. The most phylogenetically related species is Halomonas alkaliphila DSM 16354(T), with which strain NEAU-ST10-25(T) showed 16S rRNA, gyrB and rpoD gene sequence similarities of 99.2, 82.3 and 88.2 %, respectively. The results of DNA-DNA hybridization assays showed 60.47 ± 0.69 % DNA relatedness between strain NEAU-ST10-25(T) and H. alkaliphila DSM 16354(T), 42.43 ± 0.37 % between strain NEAU-ST10-25(T) and Halomonas venusta DSM 4743(T) and 30.62 ± 0.43 % between strain NEAU-ST10-25(T) and Halomonas hydrothermalis DSM 15725(T). The major fatty acids are C18:1 ω7c (62.3 %), C16:0 (17.6 %), C16:1 ω7c/C16:1 ω6c (7.7 %), C14:0 (2.9 %), C12:0 3-OH (2.8 %), C10:0 (2.1 %) and C18:1 ω9c (1.6 %) and the predominant respiratory quinone is ubiquinone 9 (Q-9). The proposed name is Halomonas zhaodongensis, NEAU-ST10-25(T) (=CGMCC 1.12286(T) = DSM 25869(T)) being the type strain.

Polystyrene microplastics trigger adiposity in mice by remodeling gut microbiota and boosting fatty acid synthesis.

Microplastic (MP) pollution has become a global environmental problem, with particular concerns for its harmful effects on human health. Several studies have demonstrated that MP can penetrate animals and humans resulting in tissue dysfunction, but their influences on metabolism remain poorly understood. In this study, we investigated the impact of MP exposure on metabolism and the results showed that different treatment doses produce a bidirectional modulatory effects on mice. When exposed to high concentrations of MP, mice lost significant weight, while those in the lowest concentration treatment group showed little change, but those treated at relatively low concentrations became overweight. There was excessive lipid accumulation in these heavier mice, with a better appetite and lower activity level. Transcriptome sequencing revealed that MPs increased fatty acid synthesis in the liver. In addition, the gut microbiota composition of the MPs-induced obese mice was remodeled, which would enhance the nutrient absorption capacity of the intestine. Our results uncovered an MP dose-dependent lipid metabolism in mice and a non-unidirectional model of the physiological responses to different MP concentrations was proposed. These results provided new insights into the seemingly contradictory effects of MP on metabolism in the previous study.