Regulation of crystal protein biosynthesis by Bacillus thuringiensis: I. Effects of mineral elements and pH

Crystal protein synthesis by a local isolate of Bacillus thuringiensis was monitored and compared in association with growth and sporulation in media differing in mineral element content. Mg and Cu were the most important metals for the biosynthesis of 135 kDa and 65 kDa toxin components in that the former was essential and the latter was greatly stimulatory at 10(-6) to 10(-7) M concentration. Also the inclusion of Mn favored toxin production at concentrations ranging from 3 x 10(-4) to 10(-5) M. The omission of Zn and Ca had no effect on toxin formation. Crystal protein synthesis and sporulation did not generally seem to be co-regulated by the minerals as these processes responded differently to mineral levels. There was no evidence for suppression of biosynthesis by inorganic phosphate over a range of 3 to 100 mM. Crystal protein production was more efficient in buffered medium, especially when the initial pH was adjusted to 6.5. (C) 2002 Editions scientifiques et medicales Elsevier SAS. All rights reserved

Isolation and characterization of bacteria capable of tin resistance

WOS: 000209805600511

Biochemical and molecular characterization of lead-resistant environmental isolates of Enterococcus faecalis

WOS: 000209805600533

Challenging tin toxicity by a novel strain isolated from freshwaters

Icgen, Bulent/0000-0001-8114-4230WOS: 000349802300003The first major challenge for the bioremediation field is to select the most promising types of biomass. Hence, the objective of this study was to isolate and identify a novel species which has the potential to remediate tin in freshwaters. For this reason, a bacterium designated as Sn11, with 59 mu g ml(-1) maximum tolerable concentration of tin was isolated selectively from the freshwater samples collected along the river Kirikkale-Kizilirmak, Turkey. Identification of the isolate was done using biochemical tests, fatty acid methyl ester analysis, and 16S rRNA sequencing. Fatty acids produced by the isolate investigated were assumed as typical for the genus Pantoea. Pantoea were highly homogeneous by dominant C-16:0 and C-16:1 cis 9 fatty acids. 16S rRNA sequence analysis also confirmed that the isolate Sn11 had 98% homology with Pantoea agglomerans. The complete sorption of 59 mu g ml(-1) tin by P. agglomerans was recorded at about 20 h incubation. Due to higher affinity toward tin sorption, P. agglomerans can be an important isolate for the natural attenuation of tin toxicity in contaminated freshwaters

Biochemical and molecular characterization of copper-resistant bacterial isolates

WOS: 000209805600546

Exposure to sulfide causes population shifts in sulfate-reducing consortia

The shift in the community structure of a mixed culture of sulfate-reducing bacteria (SRB) at 0.5, 0.75, 1, and 1.5 kg m−3 sulfide loadings was investigated in an anaerobic continuous bioreactor used for treatment of sulfate-containing wastewater by fluorescence in situ hybridization (FISH), using SRB species-specific and group-specific 16S rRNA-targeting probes. Hybridization analysis using these 16S rRNA-targeted oligonucleotide probes revealed that sulfide was toxic for Desulfonema, Desulfobulbus spp. and the Desulfobacteriaceae group, although it was not toxic for Desulfobacter, Desulfotomaculum, Desulfobacterium spp. or the Desulfovibrionaceae group. On the other hand, only a high concentration of sulfide of 1.5 kg m−3 was found to be toxic for the Desulfococcus group in the bioreactor. When the sulfide in the feed was 1.00 kg m−3 the sulfate-reducing capacity of the system decreased, and this decrease was more pronounced when the inlet sulfide was further increased to 1.5 kg m−

Characterization of lead-resistant river isolate Enterococcus faecalis and assessment of its multiple metal and antibiotic resistance

Icgen, Bulent/0000-0001-8114-4230WOS: 000318503100062PubMed: 23079796Contamination of surface waters has a direct impact on the public health of entire communities. Microorganisms inhabiting contaminated surface waters have developed mechanisms of coping with a variety of toxic metals and drugs. Investigations were carried out to isolate and identify lead-resistant bacteria from the river KA +/- zA +/- lA +/- rmak along the city of KA +/- rA +/- kkale, Turkey. Of the 33 lead-resistant isolates, one isolate with a minimal inhibitory concentration of 1,200 mg L-1 was isolated and identified as Enterococcus faecalis by using biochemical tests and 16S rRNA sequencing. Lead-resistant E. faecalis isolate was found out to be resistant to other heavy metals like aluminum, lithium, barium, chromium, iron, silver, tin, nickel, zinc, and strontium and to drugs like amikacin, aztreonam, and gentamicin. E. faecalis harbored four plasmids with the molecular sizes of 1.58, 3.06, 22.76, and 28.95 kb. Plasmid profile analyses of cured derivatives revealed that the lead resistance ability of E. faecalis was still existing despite the elimination of all the plasmids. Moreover, the antibiotic resistance pattern of the cured derivatives did not demonstrate any change from the parental strain. Our findings indicated that the lead resistance genes of E. faecalis were located on the chromosomal DNA rather than the plasmid.Kirikkale University Research FundKirikkale UniversityThis research project has been supported by Kirikkale University Research Fund

Molecular characterization of zinc-resistant bacteria isolated from industrial effluents

WOS: 000209805600648

Chromosome-encoded cadmium resistance by the river isolate of Delftia tsuruhatensis

WOS: 000209805600489