Isolation of potassium chromate-tolerant bacterium and chromate uptake by the bacterium.

Horitsu, Hiroyuki; Nishida, Haruo; Kato, Haruyasu; Tomoyeda, Mikio

doi:10.1271/bbb1961.42.2037

Cited by 12 publications

(6 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It can permeate through biological membranes and interact with intracellular proteins and nucleic acids (Horitsu et al, 1978). Lead is a hazardous metal of environmental concern with high persistency.…”

Section: The Role Of Endogenous Bacteria In Chironomids Y Senderovichmentioning

confidence: 99%

The protective role of endogenous bacterial communities in chironomid egg masses and larvae

Senderovich

Halpern

2013

The ISME Journal

View full text Add to dashboard Cite

Insects of the family Chironomidae, also known as chironomids, are distributed worldwide in a variety of water habitats. These insects display a wide range of tolerance toward metals and organic pollutions. Bacterial species known for their ability to degrade toxicants were identified from chironomid egg masses, leading to the hypothesis that bacteria may contribute to the survival of chironomids in polluted environments. To gain a better understanding of the bacterial communities that inhabit chironomids, the endogenous bacteria of egg masses and larvae were studied by 454-pyrosequencing. The microbial community of the egg masses was distinct from that of the larval stage, most likely due to the presence of one dominant bacterial Firmicutes taxon, which consisted of 28% of the total sequence reads from the larvae. This taxon may be an insect symbiont. The bacterial communities of both the egg masses and the larvae were found to include operational taxonomic units, which were closely related to species known as toxicant degraders. Furthermore, various bacterial species with the ability to detoxify metals were isolated from egg masses and larvae. Koch-like postulates were applied to demonstrate that chironomid endogenous bacterial species protect the insect from toxic heavy metals. We conclude that chironomids, which are considered pollution tolerant, are inhabited by stable endogenous bacterial communities that have a role in protecting their hosts from toxicants. This phenomenon, in which bacteria enable the continued existence of their host in hostile environments, may not be restricted only to chironomids.

show abstract

Section: The Role Of Endogenous Bacteria In Chironomids Y Senderovichmentioning

confidence: 99%

The protective role of endogenous bacterial communities in chironomid egg masses and larvae

Senderovich

Halpern

2013

The ISME Journal

View full text Add to dashboard Cite

show abstract

“…Some bacteria have Cr(VI)-reducing activities. We reported previously that Pseudomonas ambigua G-1 showed NADH-dependent Cr(VI)-reducing activity in the cell extract (11)(12)(13). Ishibashi et al.…”

mentioning

confidence: 94%

“…ambigua G-1 was able to grow in medium containing up to 20 mM K2CrO4 (13). The Cr(VI)-reducing activity (11) of this strain was more thermostable than that of other pseudomonads (14).…”

mentioning

confidence: 96%

NAD(P)H-dependent chromium (VI) reductase of Pseudomonas ambigua G-1: a Cr(V) intermediate is formed during the reduction of Cr(VI) to Cr(III)

et al. 1992

View full text Add to dashboard Cite

An NAD(P)H-dependent Cr(VI) reductase (molecular weight = 65,000) was purified from a Cr(VI)-resistant bacterium, Pseudomonas ambigua G-1. Stoichiometric analysis of the enzymatic reaction showed that the enzyme catalyzed the reduction of 1 mol of Cr(VI) to Cr(III) while consuming 3 mol of NADH as an electron donor. Chromium(VI) was reduced to Cr(V) by one equivalent NADH molecule in the absence of the enzyme.Electron spin resonance analysis showed that Cr(V) species (g = 1.979) was formed during the enzymatic reduction. The amount of Cr(V) species formed was about 10 times larger than that of the nonenzymatic reduction. These findings show that the Cr(VI) reductase reduced Cr(VI) to Cr(HI) (14) found NAD(P)H-dependent Cr(VI)-reducing activity in the cell-free supernatant fluids from Pseudomonas putida. Das and Chandra (6) have reported that Cr(VI) was reduced to Cr(III) in the presence of NAD(P)H in the cell extract of Streptomyces species. A membrane-associated chromate reduction system was also reported. Ohtake and coworkers (20) and Wang and coworkers (26)(27)(28) have shown that Cr(VI) was reduced to Cr(III) under anaerobic conditions by Enterobacter cloacae and its reduction was caused by the respiratory chain system of the cell membrane. We considered that these bacterial Cr(VI) reduction systems contribute to its detoxification by Cr(VI)-resistant bacteria. However, the Cr(VI) reductase has not yet been purified, and the details of the reaction mechanism are still unclear.P. ambigua G-1 was able to grow in medium containing up to 20 mM K2CrO4 (13). The Cr(VI)-reducing activity (11) of this strain was more thermostable than that of other pseudomonads (14). The Cr(VI)-sensitive mutants of this strain lost the reducing activity (12). These results indicate that this strain is a good source to investigate the Cr(VI) reduction mechanism which contributes to Cr(VI) detoxication.In the present paper, we report the purification of NAD(P)H-dependent Cr(VI) reductases of P. ambigua G-1 and the analysis of the catalytic mechanism of Cr(VI) reduction by the enzymes. Preparation of Cr(VI) reductase. Cells grown in 4 liters of L broth at 37°C were harvested at the late logarithmic phase, washed twice with 20 mM Tris-HCl, pH 7.2, suspended in 100 ml of the same buffer, and disrupted by sonication. After removal of the unbroken cells by centrifugation (1,500 x g, 30 min), the supernatant fluid was heat treated at 60°C for 2 min and centrifuged (1,500 x g, 30 min). The supernatant fluid was separated on a DE32 column (3.5 by 6 cm; Whatman Ltd., Maidstone, England) previously equilibrated with buffer A (50 mM glucose in 20 mM Tris-HCl, pH 7.2), and proteins were eluted with 0.4 M NaCl in buffer A at a flow rate of 100 ml/h. The fractions carrying the Cr(VI)-reducing activity were concentrated and separated by Cu2" chelate affinity chromatography using an AF-chelate Toyopearl 650M column (2.6 by 4 cm; Toso Ltd., Tokyo, Japan) which was sequentially equilibrated with 200 PM CUSO4 solution and buffer B (0.5 M NaCl in buf...

show abstract

“…Sludge deposition from such effluents, therefore, provides a natural environment for enrichment of chromium-resistant bacteria. Chromium-resistant microorganisms from such chromiumcontaminated sediments have been isolated by several investigators (Horitsu et al 1978;Luli et al 1983;Losi and Frankenberger 1993).…”

mentioning

confidence: 99%

Isolation and Characterization of Chromium-Resistant Bacteria from Tannery Effluents

Basu

Bhattacharya

Paul

1997

Bulletin of Environmental Contamination and Toxicology

View full text Add to dashboard Cite

Isolation of potassium chromate-tolerant bacterium and chromate uptake by the bacterium.

Cited by 12 publications

References 0 publications

The protective role of endogenous bacterial communities in chironomid egg masses and larvae

The protective role of endogenous bacterial communities in chironomid egg masses and larvae

NAD(P)H-dependent chromium (VI) reductase of Pseudomonas ambigua G-1: a Cr(V) intermediate is formed during the reduction of Cr(VI) to Cr(III)

Isolation and Characterization of Chromium-Resistant Bacteria from Tannery Effluents

Contact Info

Product

Resources

About