Alleviation of hexavalent chromium by using microorganisms: insight into the strategies and complications.

Excessive industrialization and anthropogenic activities have resulted in widespread prevalence of heavy metals including hexavalent chromium in the environment. In addition to toxic properties, Cr(VI) possesses high stability and mobility, which in total makes it included in the list of priority heavy metals; thus it needs to be managed urgently. Among different methods available for remediation of Cr(VI), bioremediation is considered as one of the sustainable methods which could effectively be utilized for controlling Cr(VI) pollution. In this aspect, the treatment of Cr(VI)-containing wastewater originating from industries is noteworthy. The present review thus is an attempt to present a systematic overview dealing with studies on remediation of hexavalent chromium by using microorganisms and their application in treatment of Cr(VI)-containing industrial wastewaters. Various factors affecting the Cr(VI) removal and methods to enhance the bio-treatment are highlighted, which might act as a basis for researchers developing Cr(VI) bioremediation techniques.

Efficacy of Acinetobacter sp. B9 for simultaneous removal of phenol and hexavalent chromium from co-contaminated system.

The present study shows the feasibility of a newly isolated strain Acinetobacter sp. B9 for concurrent removal of phenol and Cr (VI) from wastewater. The experiments were conducted in a batch reactor under aerobic conditions. Initially, when mineral salt solution was used as the culture medium, the strain was found to utilize phenol as sole carbon and energy source while no Cr (VI) removal was observed. However, the addition of glucose as co-carbon source resulted in the removal of both toxicants. This co-removal efficiency of the strain was further improved with nutrient-rich media (NB). Optimum co-removal was determined at 188 mg L(-1) of phenol and 3.5 mg L(-1) of Cr (VI) concentrations at pH 7.0. Strain B9 followed the orthometabolic pathway for phenol degradation. Transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FT-IR) studies showed sorption of chromium as one of the major mechanisms for Cr (VI) removal by B9 cells. Acinetobacter sp. B9 was later on checked for bioremediation of real tannery wastewater. After 96 h of batch treatment of tannery effluent containing an initial 47 mg L(-1) phenol and 16 mg L(-1) Cr (VI), complete removal of phenol and 87 % reduction of Cr (VI) were attained, showing high efficiency of the bacterial strain for potential application in industrial pollution control.

Insulin induces fatty acid desaturase expression in human monocytes.

Increasing evidence suggests that fatty acid desaturases, rate-limiting enzymes in unsaturated fatty acid biosynthesis, are important factors in the pathogenesis of lipid-induced insulin resistance. The conversion of dihomogamma linolenic acid (DGLA) into arachidonic acid (AA) in human plasma phospholipids has been shown to be regulated by insulin, suggesting a role for insulin in fatty acid desaturase 1 regulation. However insulin's role in monocyte inflammation associated with obesity and lifestyle disease development is uncertain. We therefore investigated if insulin is able to induce expression of stearoyl-CoA desaturase (SCD, Δ9 desaturase), fatty acid desaturase 1 (FADS1, Δ5 desaturase), and fatty acid desaturase 2 (FADS2, Δ6 desaturase), as well as the sterol regulatory element binding transcription factor 1-c (SREBP-1c) in monocytes. Here, for the first time, we demonstrate that THP-1 monocytes are insulin-responsive in inducing expression of SCD, FADS1, and FADS2 in a time- and dose-dependent manner. Understanding secondary consequences of postprandial hyperinsulinemia may open up new strategies for prevention and/or treatment of obesity-related metabolic complications.