Role of biochar and organic substrates in enhancing the functional characteristics and microbial community in a saline soil.

In sustaining the soil quality, soil salinization has become a major challenge due to the increasing salinity rate of 10% annually. Despite, the serious concerns, the influence of soil amendments on microbial communities and its related attributes have limited findings. Therefore, the present study aims to investigate the potential of three various biochars, digestate (DI), and its compost (COM) in reclamation of saline soil under closed ecosystem. The decrease in the pH was displayed by lignite char, and electrical conductivity by lignite char plus COM addition among all the treatments. The subside in Na +, with a significant rise in K +, was exhibited in soils amended with DI plus DI biochar as a combined ameliorate over control. The negative priming effects on native soil organic carbon (nSOC) due to the decreased substrate bioavailability, in corn straw and DI biochars ameliorates were noted. The urease and alkaline phosphatase activity were pronounced higher in COM. However, the catalase and fluorescein diacetate activity were greater in lignite char plus DI and COM respectively. The co-addition of biochar and organic substrates shifted microbial community, is in correspondence with the relative abundance of the phylum. Overall, the abundance of Firmicutes and Actinobacteria was higher in soils under a combination of lignite char with DI and COM respectively. Likely, the abundance of Euryarchaeota was dominant in the co-application of corn straw biochar and DI. Redundancy analysis revealed the intactness between bacterial genera and their metabolisms with K +, and Mg 2+. PICRUSt disclosed the enhanced metabolic functions in soil with amalgam of DI and its biochar. The findings showed that the application of DI and its biochar mixture, as an amendment could be a better approach in the long-term reclamation of saline soil.

Enhanced methane production from microalgal biomass by anaerobic bio-pretreatment.

Anaerobic digestion (AD) of microalgal biomass is one of the most energy efficient technologies to convert microalgae to biofuels. In order to improve the biogas productivity, breaking up the tough and rigid cell wall of microalgae by pretreatment is necessary. In this work, Bacillus licheniformis, a facultative anaerobic bacterial with hydrolytic and acidogenic activities, was adopted to pretreat Chlorella sp. In the established pretreatment process, pure bacterial culture (0%, 1%, 2%, 4%, 8%, v/v) were used to pretreat Chlorella sp. under anaerobic condition at 37°C for 60 h. The soluble chemical oxygen demands (SCOD) content was increased by 16.4-43.4%, while volatile fatty acids (VFAs) were improved by 17.3-44.2%. Furthermore, enhancement of methane production (9.2-22.7%) was also observed in subsequent AD. The results indicated that the more dosages of bacteria were used to pretreat the microalgal biomass in the range of 1-8%, the more methane was produced.

The chemical properties and microbial community characterization of the thermophilic microaerobic pretreatment process.

Thermophilic microaerobic pretreatment (TMP) was recently reported as an efficient pretreatment method of anaerobic digestion (AD). In this study, the chemical properties and microbial community were characterized to reveal how TMP working. Compared with thermophilic treatment under anaerobic condition (TMP0), cellulase activity obviously improved under microaerobic condition (TMP1), which was 10.9-49.0% higher than that of TMP0. Reducing sugar, SCOD and VFAs concentrations of TMP1 were 2.6-8.9%, 1.8-4.8% and 13.8-24% higher than those of TMP0, respectively. TMP gave obvious rise to phylum Firmicutes, which associated with extracellular enzymes production. The proportion of class Bacilli (belongs to phylum Firmicutes and mainly acts during hydrolysis) in TMP1 was 124.89% higher than that of TMP0, which reflected the greater hydrolytic ability under microaerobic condition. The improved abundance of phylum Firmicutes (especially class Bacilli, order Bacillales) under microaerobic condition could be the fundamental reason for the improved AD performance of thermophilic microaerobic pretreated corn straw.