Pear pomace soluble dietary fiber ameliorates the negative effects of high-fat diet in mice by regulating the gut microbiota and associated metabolites.

The gut microbiota and related metabolites are positively regulated by soluble dietary fiber (SDF). In this study, we explored the effects of SDF from pear pomace (PP) on the regulation of gut microbiota and metabolism in high-fat-diet-fed (HFD-fed) C57BL/6J male mice. The results showed that PP-SDF was able to maintain the HFD disrupted gut microbiota diversity with a significant increase in Lachnospiraceae_UCG-006, Akkermansia, and Bifidobacterium spp. The negative effects of high-fat diet were ameliorated by PP-SDF by regulating lipid metabolisms with a significant increase in metabolites like isobutyryl carnitine and dioscoretine. Correlation analysis revealed that gut microbiota, such as Akkermansia and Lachnospiraceae_UCG-006 in the PP-SDF intervention groups had strong positive correlations with isobutyryl carnitine and dioscoretin. These findings demonstrated that PP-SDF interfered with the host's gut microbiota and related metabolites to reduce the negative effects caused by a high-fat diet.

The influence of factors on dewaterability of one-stage autothermal thermophilic aerobically digested sludges.

One-stage auto thermophilic aerobic digestion (ATAD) could achieve the same sludge stabilization efficiency as two- or multi-stage ATAD process does. However, the dewaterability of sludge might be affected through thermophilic digestion because of the release of intracellular substances under the thermophilic temperatures. This paper investigated which operation factors affect intracellular substances released in the liquid phase of sludge that lead to different extent of dewaterability. The results showed that optimal digestion time needs to be prolonged up to 480 h to avoid a deteriorated dewaterability phase. The deterioration in dewaterability of the sludge could be minimized at a retention time of 360 h (i.e., 15 days) under a digestion temperature of 65 °C. Specific capillary suction time (SCST) had quadratic correlations with SCOD, protein (PN) and polysaccharides (PS) in the liquid phase. The coefficient between SCST and the ratio of PN/PS had a value of 0.9764, indicating that the sludge dewaterability was significantly deteriorated by biopolymer of protein and polysaccharides in supernatant.

Combined mesophilic anaerobic and thermophilic aerobic digestion process: effect on sludge degradation and variation of sludge property.

One-stage autothermal thermophilic aerobic digestion (ATAD) is effective for the reduction of volatile solids (VSs) and pathogen in sewage sludges. A novel process of combining mesophilic (<35 °C) anaerobic digestion with a thermophilic (55 °C) aerobic digestion process (AN/TAD) occurred in a one-stage digester, which was designed for aeration energy savings. The efficiency of sludge degradation and variation of sludge properties by batch experiments were evaluated for the AN/TAD digester with an effective volume of 23 L for 30 days compared with conventional thermophilic aerobic digestion (TAD). The AN/TAD system can efficiently achieve sludge stabilization on the 16th day with a VS removal rate of 38.1 %. The AN/TAD system was operated at lower ORP values in a digestion period with higher contents of total organic compounds, volatile fatty acids, protein, and polysaccharide in the soluble phase than those of the TAD system, which can rapidly decreased and had low values in the late period of digestion for the AN/TAD system. In the AN/TAD system, intracellular substances had lysis because of initial hydrolytic acidification.