Polyphasic characterization of Delftia acidovorans ESM-1, a facultative methylotrophic bacterium isolated from rhizosphere of Eruca sativa

Research on carbon and nitrogen removal of tetramethylammonium hydroxide containing wastewater by combined anaerobic/integrated fixed film activated sludge process

Tetramethylammonium hydroxide (TMAH) is widely used as a developer and etchant in the thin-film transistor liquid crystal display industry, which is the main component of developer wastewater with low C/N ratio. This study investigated TMAH degradation by combined anaerobic/integrated fixed film activated sludge (A/IFAS) process, especially for nitrogen removal. Effects of process condition on the TMAH degradation were studied, including dissolved oxygen concentration in IFAS reactor and the temperature of anaerobic reactor. Especially, the nitrogen removal was studied through the monitoring of intermediate products during TMAH biodegradation. The results indicated that lower the anaerobic treatment temperature can provide more available organic matters to enhance the denitrification in the subsequent IFAS reactor. Less oxygen supply in the IFAS reactor contributed to simultaneous nitrification and denitrification. Removal efficiency of total organic carbon and total nitrogen was up to 95.8% and 80.7%, when the temperature of anaerobic treatment was controlled at 30 °C with the DO kept at 0.7 mg/L. It indicated that A/IFAS process was efficient in carbon and nitrogen removal for TMAH degradation. The results also confirmed intermediate products of TMAH biodegradation can be used as the electron donor during denitrification, including trimethylamine, dimethylamine and methylamine. Illumina MiSeq sequencing showed that Proteobacteria was the dominant phylum contribute to nitrogen removal. Compared to sludge flocs in IFAS reactor, richer community and higher microbial diversity were observed in the biofilm.

Plant growth promoting bacteria drive food security

The essence of food security centers on ensuring availability and accessibility of foods in adequate amounts and quality for all populations at all times for an active and healthy life. Microorganisms are tiny bioreactors, which represent sustainable resources and promising approaches to bridging the gap between food production and consumption globally via various biotechnological applications. This review focuses on plant-growth promoting bacteria (PGPB) which exert their potential impacts on increasing soil fertility, plant growth, and productivity through a variety of processes, including direct, indirect, and synergistic mechanisms. PGPB plays a substantial role in accelerating nutrients' availability such as (N, P), producing phytohormones such as gibberellins, IAA, and bioactive compounds against biotic and abiotic stressors. Recent advances in PGPB will be addressed as a sustainable approach to satisfy global food demand.

Enrichment and characterization of an effective hexavalent chromium-reducing microbial community YEM001

Chromium (Cr) is one of the most widely used heavy metals in industrial processes, resulting in water and soil pollution that seriously threaten environmental safety. In this paper, we have directionally enriched a Cr(VI)-reducing bacterial community YEM001 from no-Cr(VI) polluted pond sedimental sludge by selectively growing it in Cr(VI)-containing media. This community could effectively reduce Cr(VI) in laboratory rich media containing different concentrations of Cr(VI), such as 61% reduction at 435 mg/L Cr(VI), 85% reduction at 355 mg/L Cr(VI), and complete reduction at 269 mg/L Cr(VI) in 93.5 h. It was also able to completely reduce 100 mg/L and 300 mg/L Cr(VI) in landfill leachate and natural sludge in 48 h, respectively. Optimal pH for Cr(VI) reduction of the YEM001 is between 7 and 8 and the best efficiency for Cr(VI) reduction occurs at 30 °C. Metagenomic data demonstrated that the YEM001 community was composed of multiple bacteria, including well-known Cr(VI)-reducing bacteria and non-Cr(VI)-reducing bacteria. Delftia, Comamonas, Alicycliphilus, Acidovorax, Bacillus, and Clostridioides account for 83% of total community abundance. The stability of the composition of the YEM001 community and its Cr(VI)-reducing activity allows for its application in bioremediation of environmental Cr(VI) pollution.