Optimization of a bacterial consortium for nitrobenzene degradation

Aberrant upregulation of the glycolytic enzyme PFKFB3 in CLN7 neuronal ceroid lipofuscinosis

CLN7 neuronal ceroid lipofuscinosis is an inherited lysosomal storage neurodegenerative disease highly prevalent in children. CLN7/MFSD8 gene encodes a lysosomal membrane glycoprotein, but the biochemical processes affected by CLN7-loss of function are unexplored thus preventing development of potential treatments. Here, we found, in the Cln7∆ex2 mouse model of CLN7 disease, that failure in autophagy causes accumulation of structurally and bioenergetically impaired neuronal mitochondria. In vivo genetic approach reveals elevated mitochondrial reactive oxygen species (mROS) in Cln7∆ex2 neurons that mediates glycolytic enzyme PFKFB3 activation and contributes to CLN7 pathogenesis. Mechanistically, mROS sustains a signaling cascade leading to protein stabilization of PFKFB3, normally unstable in healthy neurons. Administration of the highly selective PFKFB3 inhibitor AZ67 in Cln7∆ex2 mouse brain in vivo and in CLN7 patients-derived cells rectifies key disease hallmarks. Thus, aberrant upregulation of the glycolytic enzyme PFKFB3 in neurons may contribute to CLN7 pathogenesis and targeting PFKFB3 could alleviate this and other lysosomal storage diseases.

An in-situ bio-remediation of nitrobenzene in stimulated aquifer using emulsified vegetable oil

Widespread nitrobenzene (NB) contamination in groundwater requires an economical and effective remediation technology. In situ microbial reactive zone enhanced by injecting emulsified vegetable oil (EVO) is an effective method for remediating NB-contaminated groundwater, which can be reduced to aniline (AN) effectively in the reactive zone. However, the bio-mechanism of NB remediation in a real contaminated site is still unclear. Thus, a 3-D tank was established to conduct a pilot-scale experiment and the bacterial communities in the tank were analyzed by 16S rDNA high-throughput sequencing. The results suggested that the injection of EVO can stimulate some certain microorganisms to grow, and reduce NB though biological and biochemical processes. There were three degradation pathways of NB: (1) direct oxidation by Pseudomonas; (2) direct mineralization by Clostridium sensu stricto; and (3) coupled reduction of NB through microbial dissimilatory iron reduction by Geobacter and Arthrobacter. Among these pathways, the coupled reduction process is the main degradation pathway.

Genetically engineered thermotolerant facultative anaerobes for high-efficient degradation of multiple hazardous nitroalkanes

Nitroalkanes are important industrial raw materials but also toxic pollutants, which are difficult to degrade once released into the environment. In this study, to significantly improve the degradation-efficiency of multiple nitroalkanes, a facultative anaerobe was genetically engineered, possible influencing factors and simulated application experiments of bioreactor were tested and evaluated. Among all engineered recombinants, the most effective strains NG-S1 (anaerobic) and NG-S2 (aerobic) displayed 2-fold and 2.8-fold final degradation rates higher than the wild type, respectively. Exogenous components, particularly those that enhance coenzyme synthesis, helped to increase the degradation rate, as the level of coenzymes affected full function of overexpressed nitroalkane oxidase. Importantly, simulated mixed-nitroalkane-wastewater bioreactor experiments proved excellent and sustainable degradation performance of the engineered strains for potential industrial applications. Collectively, these findings provide a promising thermophilic biological engineering platform and a new perspective for high-efficient and continuous environmental bioremediation of hazardous pollutants under aerobic and anaerobic conditions.

Biodegradation of crude oil by a defined co-culture of indigenous bacterial consortium and exogenous Bacillus subtilis

The aim of this work was to study biodegradation of crude oil by defined co-cultures of indigenous bacterial consortium and exogenous Bacillus subtilis. Through residual oil analysis, it is apparent that the defined co-culture displayed a degradation ratio (85.01%) superior to indigenous bacterial consortium (71.32%) after 7days of incubation when ratio of inoculation size of indigenous bacterial consortium and Bacillus subtilis was 2:1. Long-chain n-alkanes could be degraded markedly by Bacillus subtilis. Result analysis of the bacterial community showed that a decrease in bacterial diversity in the defined co-culture and the enrichment of Burkholderiales order (98.1%) degrading hydrocarbons. The research results revealed that the promising potential of the defined co-culture for application to degradation of crude oil.

Toxicity and Microbial Degradation of Nitrobenzene, Monochloronitrobenzenes, Polynitrobenzenes, and Pentachloronitrobenzene

Nitrobenzene and its derivatives (NBDs) are highly toxic compounds that have been released into the environment by anthropogenic activities. Many bacteria and fungi have been well-characterized for their ability to degrade NBDs. The biochemical and molecular characterization of the microbial degradation of NBDs has also been studied. In this review, we have summarized the toxicity and degradation profiles of nitrobenzene, monochloronitrobenzenes, polynitrobenzenes, and pentachloronitrobenzene. This review will increase our current understanding of toxicity and microbial degradation of NBDs.

Interspecific interactions in mixed microbial cultures in a biodegradation perspective

In recent works, microbial consortia consisting of various bacteria and fungi exhibited a biodegradation performance superior to single microbial strains. A highly efficient biodegradation of synthetic dyes, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and other organic pollutants can be achieved by mixed microbial cultures that combine degradative enzyme activities inherent to individual consortium members. This review summarizes biodegradation results obtained with defined microbial cocultures and real microbial consortia. The necessity of using a proper strategy for the microbial consortium development and optimization was clearly demonstrated. Molecular genetic and proteomic techniques have revolutionized the study of microbial communities, and techniques such as the denaturing gradient gel electrophoresis, rRNA sequencing, and metaproteomics have been used to identify consortium members and to study microbial population dynamics. These analyses could help to further enhance and optimize the natural activities of mixed microbial cultures.