In the present study, the ability of a newly isolated strain, Methylobacterium sp. XJLW to degrade formaldehyde was investigated in shake flasks and in a bioreactor. The resting cells of Methylobacterium sp. XJLW showed high formaldehyde tolerance (60 g L(-1)) and high degradation rate (1,687.5 mg L(-1) h(-1)) in shake flasks. This biodegradation was initiated by a dismutation reaction since formic acid was formed and caused significant dropping of pH in the media. The addition of CaCO(3) to the media was found as an effective strategy to control the pH and keep the cells in high degradation bioactivity. A three-phase fluidized bed reactor (TPFBR) was designed to test the formaldehyde-biodegrading ability of immobilized Methylobacterium sp. XJLW. Using a repeated-batch degradation mode, the immobilized cells were able to degrade 5 g L(-1) formaldehyde (with a maximal degradation rate of 464.5 mg L(-1) h(-1) under the optimum conditions) and showed stable bioactivity after 20 batches of reuse in the TPFBR.
Dibutyl phthalate (DBP) is an environmental pollutant that can threaten human health. The strain Arthrobacter sp. ZJUTW, isolated from the sludge of river of Hangzhou city, can efficiently degrade DBP. Its genomic and transcriptomic differences when cultivated with DBP and with glucose revealed specific DBP metabolic pathways in the ZJUTW strain. The degrading gene clusters distribute separately on a circular chromosome and a plasmid pQL1. Genes related to the initial steps of DBP degradation from DBP to phthalic acid (PA), the pehA gene and pht gene cluster, are located on the plasmid pQL1. While pca gene cluster related to the transforming of protocatechuic acid (PCA) to acetyl-CoA, is located on the chromosome. After homologous alignment analysis with the reported gene clusters, we found that there were a series of double copies of homologous genes in pht and pca gene clusters that contribute to the efficient degradation of DBP by ZJUTW. In addition, transcriptomic analysis showed a synergistic effect between pht and pca clusters, which also favor ZJUTW allowing it to efficiently degrade DBP. Combined genomic and transcriptomic analyses affords the complete DBP metabolic pathway in Arthrobacter sp. ZJUTW that is different from that of reported other Arthrobacter strains. After necessary modification based on its metabolic characteristics, Arthrobacter sp. ZJUTW or its mutants might represent promising candidates for use in the bioremediation of DBP pollution.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.