scholarly journals Chromate Reduction by a Pseudomonad Isolated from a Site Contaminated with Chromated Copper Arsenate

2001 ◽  
Vol 67 (3) ◽  
pp. 1076-1084 ◽  
Author(s):  
Jeff McLean ◽  
Terry J. Beveridge
Keyword(s):  
Reductase Activity ◽  
Wood Preservation ◽  
Chromate Reduction ◽  
Anaerobic Conditions ◽  
Toxic Heavy Metal ◽  
Metal Metal ◽  
A Site ◽  
Anaerobic Reduction ◽  
Aerobic And Anaerobic ◽  
Aerobic And Anaerobic Conditions

ABSTRACT A pseudomonad (CRB5) isolated from a decommissioned wood preservation site reduced toxic chromate [Cr(VI)] to an insoluble Cr(III) precipitate under aerobic and anaerobic conditions. CRB5 tolerated up to 520 mg of Cr(VI) liter−1 and reduced chromate in the presence of copper and arsenate. Under anaerobic conditions it also reduced Co(III) and U(VI), partially internalizing each metal. Metal precipitates were also found on the surface of the outer membrane and (sometimes) on a capsule. The results showed that chromate reduction by CRB5 was mediated by a soluble enzyme that was largely contained in the cytoplasm but also found outside of the cells. The crude reductase activity in the soluble fraction showed aKm of 23 mg liter−1 (437 μM) and a V max of 0.98 mg of Cr h−1 mg of protein−1 (317 nmol min−1 mg of protein−1). Minor membrane-associated Cr(VI) reduction under anaerobiosis may account for anaerobic reduction of chromate under nongrowth conditions with an organic electron donor present. Chromate reduction under both aerobic and anaerobic conditions may be a detoxification strategy for the bacterium which could be exploited to bioremediate chromate-contaminated or other toxic heavy metal-contaminated environments.

scholarly journals Calcite and vaterite biosynthesis by nitrate dissimilating bacteria in carbonatogenesis process under aerobic and anaerobic conditions

2019 ◽  
Author(s):  
Marwa Eltarahony ◽  
Sahar Zaki ◽  
Ayman Kamal ◽  
Desouky Abd-El-Haleem
Keyword(s):  
Nitrate Reduction ◽  
Reductase Activity ◽  
Specific Property ◽  
Bacterial Strains ◽  
Anaerobic Conditions ◽  
Lysinibacillus Sphaericus ◽  
Nucleation Sites ◽  
First Time ◽  
Aerobic And Anaerobic ◽  
Aerobic And Anaerobic Conditions

Abstract. This study deals with 16S rDNA identified bacteria, Lysinibacillus sphaericus (71A), Raoultella planticola (VIP), and Streptomyces pluricolorescens (EM4) capable of precipitating CaCO3 through a nitrate reduction aerobically and anaerobically. The produced CaCO3 crystals were analyzed using XRD, EDX, and SEM. The results showed that the carbonatogenic bacteria served as nucleation sites for CaCO3 precipitation with distinct variation in polymorph and morphology; reflecting strain-specific property. Notably, the amount of precipitated CaCO3 recorded 3.27 (aerobic), 1.55 (anaerobic), 4.15 (aerobic), 3.75 (aerobic) and 1.87 (anaerobic) g/100 mL of strains 71A, EM4 and VIP, respectively, for 240 h of incubation. The study of changes in media chemistry during carbonatogenesis process revealed positive correlation between bacterial growth, nitrate reductase activity, pH, EC, amount of deposited CaCO3 and NO3− consumption. Therefore, the applications of these bacterial strains, which employed for the first time in carbonatogenesis process, are promising in the environmental, biomedical and civil engineering fields.

scholarly journals Mycobacterium smegmatis does not display functional redundancy in nitrate reductase enzymes

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0245745
Author(s):  
Nicole C. Cardoso ◽  
Andrea O. Papadopoulos ◽  
Bavesh D. Kana
Keyword(s):  
Nitrate Reductase ◽  
Mycobacterium Smegmatis ◽  
Reductase Activity ◽  
Nitrate Assimilation ◽  
Anaerobic Conditions ◽  
Relative Contribution ◽  
Allelic Replacement ◽  
Encoding Genes ◽  
Aerobic And Anaerobic ◽  
Aerobic And Anaerobic Conditions

Reduction of nitrate to nitrite in bacteria is an essential step in the nitrogen cycle, catalysed by a variety of nitrate reductase (NR) enzymes. The soil dweller, Mycobacterium smegmatis is able to assimilate nitrate and herein we set out to confirm the genetic basis for this by probing NR activity in mutants defective for putative nitrate reductase (NR) encoding genes. In addition to the annotated narB and narGHJI, bioinformatics identified three other putative NR-encoding genes: MSMEG_4206, MSMEG_2237 and MSMEG_6816. To assess the relative contribution of each, the corresponding gene loci were deleted using two-step allelic replacement, individually and in combination. The resulting strains were tested for their ability to assimilate nitrate and reduce nitrate under aerobic and anaerobic conditions, using nitrate assimilation and modified Griess assays. We demonstrated that narB, narGHJI, MSMEG_2237 and MSMEG_6816 were individually dispensable for nitrate assimilation and for nitrate reductase activity under aerobic and anaerobic conditions. Only deletion of MSMEG_4206 resulted in significant reduction in nitrate assimilation under aerobic conditions. These data confirm that in M. smegmatis, narB, narGHJI, MSMEG_2237 and MSMEG_6816 are not required for nitrate reduction as MSMEG_4206 serves as the sole assimilatory NR.

Oxygen concentration affects frequency and range of transconjugants for the incompatibility (Inc) P-1 and P-7 plasmids pBP136 and pCAR1

2020 ◽  
Vol 85 (4) ◽  
pp. 1005-1015
Author(s):  
Kentaro Ochi ◽  
Maho Tokuda ◽  
Kosuke Yanagiya ◽  
Chiho Suzuki-Minakuchi ◽  
Hideaki Nojiri ◽  
...  
Keyword(s):  
Oxygen Concentration ◽  
Anaerobic Condition ◽  
Environmental Samples ◽  
Aerobic Condition ◽  
Recipient Strain ◽  
Donor Strain ◽  
Anaerobic Conditions ◽  
Filter Mating ◽  
Aerobic And Anaerobic ◽  
Aerobic And Anaerobic Conditions

ABSTRACT The frequency of transconjugants were compared for the incompatibility (Inc) P-1 and P-7 plasmids pBP136 and pCAR1 under aerobic and anaerobic conditions. Filter mating assays were performed with one donor strain and one recipient strain using different donors of Pseudomonas and recipient strains, including Pseudomonas, Pantoea, and Buttiauxella. Under anaerobic condition, frequencies of transconjugants for both plasmids were 101-103-fold lower than those under aerobic condition regardless of whether aerobically or anaerobically grown donors and recipients were used. To compare the transconjugant ranges under aerobic and anaerobic conditions, conjugation was performed between the donor of pBP136 and recipient bacteria extracted from environmental samples. Several transconjugants were uniquely obtained from each aerobic or anaerobic condition. Our findings indicate that a plasmid can differently spread among bacteria depending on the oxygen concentrations of the environment.

PRODUCTION AND PROPERTIES OF 2,3-BUTANEDIOL: VII. FERMENTATION OF WHEAT BY AEROBACILLUS POLYMYXA UNDER AEROBIC AND ANAEROBIC CONDITIONS

1946 ◽  
Vol 24f (1) ◽  
pp. 1-11 ◽  
Author(s):  
G. A. Adams
Keyword(s):  
Carbon Dioxide ◽  
Anaerobic Fermentation ◽  
Anaerobic Conditions ◽  
Mechanical Agitation ◽  
Fermentation Time ◽  
Aerobic Conditions ◽  
Ethanol Formation ◽  
Time Required ◽  
Aerobic And Anaerobic ◽  
Aerobic And Anaerobic Conditions

Aeration by mechanical agitation of 15% wheat mash fermented by Aerobacillus polymyxa inhibited the formation of 2,3-butanediol and particularly of ethanol. Aeration of similar mashes by passage of finely dispersed air or oxygen at the rate of 333 ml. per minute per litre of mash increased the rate of formation and yield of 2,3-butanediol but inhibited ethanol formation. However, the over-all time required for the completion of fermentation was not shortened from the usual 72 to 96 hr. required for unaerated mashes. There was no evidence of a shift from fermentative to oxidative dissimilation. Under aerobic conditions, the final butanediol–ethanol ratio was approximately 3:1. Anaerobic conditions, as produced by the passage of nitrogen or hydrogen through the mash, increased the rate of formation of both butanediol and ethanol and shortened the fermentation time to about 48 hr. Under these conditions, the butanediol–ethanol ratio was reduced to about 1.3:1.0. Carbon dioxide gave a butanediol–ethanol ratio resembling that of anaerobic fermentation but did not reduce fermentation time.

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