Reduction of hexavalent chromium (VI) by indigenous alkaliphilic and halotolerantMicrobacteriumsp. M5: comparative studies under growth and nongrowth conditions

Abstract

Aims To evaluate hexavalent chromium (Cr (VI)) reduction potential of indigenous isolate M5, under growing and nongrowing conditions. Methods and Results Microbacterium sp. M5 was isolated from soil samples collected from a common effluent treatment plant, after enrichment of indigenous microbial diversity in the presence of 200 mg l−1 of Cr (VI). The isolate achieved complete reduction of 400 mg l−1 Cr (VI) supplement to Luria Bertani medium having initial pH of 9·0 after 48 h incubation. Furthermore, the reduction potential of resting and surfactant treated cell membrane compromised cells of M5 was evaluated. The control and biosurfactant treated cells achieved 22·71 ± 0·5% and 40·56 ± 0·5% reduction of 50 mg l−1 Cr (VI) in Tris‐HCl buffer, under resting cells conditions. To the best of our knowledge, this is the first report where cells with compromised cell membrane obtained after exposure to biosurfactant have been evaluated for Cr (VI) reduction. Conclusion The Cr (VI) reduction potential of Microbacterium sp. M5 could be effectively exploited for treatment of chromium‐rich effluents, under nongrowing conditions. Significance and Impact of the Study The isolate M5 could be a potential inoculum for effluent treatment plants as it is able to support Cr (VI) reduction under wide range of pH, salinity and in the presence of different metal ions.

Comparative Genomics of Microbacterium Species to Reveal Diversity, Potential for Secondary Metabolites and Heavy Metal Resistance

“…Several studies associated these bacteria to metal contaminated sites. Several Microbacterium strains can survive in heavy metal contaminated environments ( Brown et al, 2012 ; Fidalgo et al, 2016 ), reduce specific metals such as hexavalent chromium ( Henson et al, 2015 ; Fierros-Romero et al, 2016 ; Kumar and Saini, 2019 ) and change the mobility of heavy metals in contaminated soils ( Kuffner et al, 2010 ; Soni et al, 2013 ). Because of these interesting traits, they have already been used in phytoextraction trials for soil decontamination ( Visioli et al, 2015 ).…”

Isolation and characterization of a heavy metal- and antibiotic-tolerant novel bacterial strain from a contaminated culture plate of Chlamydomonas reinhardtii, a green micro-alga.

“…Several heavy metal-tolerant environmental isolates of Microbacterium exist in the literature. 15,[20][21][22][23][24][25][26] One of the two nearest relatives of Clip185, M. binotii strain PK1-12M, was isolated from primary peat swamp forest soil in the Suratthani Province of Thailand (Accession number: MN428150.1). Peat soils are known to be enriched in heavy metals, especially in raised bogs located near mining and smelting areas.…”

“…There are several reports of Microbacterium sp. thriving in heavy metal-contaminated environments, 15,20,21 reducing heavy metals like hexavalent chromium (Cr 6+ ) [22][23][24] and showing the ability to alter the mobility of heavy metals in contaminated soils. 25,26 We tested for Clip185 tolerance of heavy metal stress induced by toxic concentrations of six heavy metals namely zinc (Zn), copper (Cu 2+ ), cadmium (Cd), cobalt (Co 2+ ), nickel (Ni 2+ ) and, hexavalent chromium (Cr 6+ ).…”

Isolation and characterization of a heavy metal- and antibiotic-tolerant novel bacterial strain from a contaminated culture plate of Chlamydomonas reinhardtii, a green micro-alga.

“…There are several reports of Microbacterium sp. thriving in heavy metal-contaminated environments, 15 , 20 , 21 reducing heavy metals like hexavalent chromium (Cr 6+ ) 22 – 24 and showing the ability to alter the mobility of heavy metals in contaminated soils. 25 , 26 We tested Clip185’s ability to tolerate heavy metal stress induced by toxic concentrations of six heavy metals namely zinc (Zn), copper (Cu 2+ ), cadmium (Cd), cobalt (Co 2+ ), nickel (Ni 2+ ) and, hexavalent chromium (Cr 6+ ).…”