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1.
Although resistance of microorganisms to Hg(II) salts has been widely investigated and resistant strains have been reported from many eubacterial genera, there are few reports of mercuric ion resistance in extremophilic microorganisms. Moderately thermophilic mercury resistant bacteria were selected by growth at 62 °C on Luria agar containing HgCl2. Sequence analysis of 16S rRNA genes of two isolates showed the closest matches to be with Bacillus pallidus and Ureibacillus thermosphaericus. Minimum inhibitory concentration (MIC) values for HgCl2 were 80 μg/ml and 30 μg/ml for these isolates, respectively, compared to 10 μg/ml for B. pallidus H12 DSM3670, a mercury-sensitive control. The best-characterised mercury-resistant Bacillus strain, B. cereus RC607, had an MIC of 60 μg/ml. The new isolates had negligible mercuric reductase activity but removed Hg from the medium by the formation of a black precipitate, identified as HgS by X-ray powder diffraction analysis. No volatile H2S was detected in the headspace of cultures in the absence or presence of Hg2+, and it is suggested that a new mechanism of Hg tolerance, based on the production of non-volatile thiol species, may have potential for decontamination of solutions containing Hg2+ without production of toxic volatile H2S.  相似文献   

2.
As part of our effort at establishing microbial consortia of relevance for the bioremediation of xenobiotics polluted environments in Mexico, we assessed the aerobic biodegradation of 2,4-dichlorophenol (2,4-DCP) by a consortium of four Bacillus species that were isolated from a polluted soil by enrichment using a mixture of chlorophenols. The bacterial consortium effectively biodegraded 2-chlorophenol, 3-chlorophenol and 2,4-dichlorophenol at degradation rates of between 1.7 and 6.7 μmoles l−1 h−1. In the presence of NH4Cl or KNO2 as nitrogen sources, 2,4-DCP was variously degraded. Under both conditions, cell biomass attained highest values of 350 and 450 mg l−1 respectively, while the amounts of 2,4-DCP metabolized in 21 days reached peak values of 2.1 and 2.5 mM representing between 70 and 85% degradation respectively. Chloride releases during the same period were highest at 4.7 mM and 5.3 mM in the presence of the two nitrogen sources. The presence of free-chloride in the culture medium had a significant impact on the catabolism of 2,4-dichlorophenol.  相似文献   

3.
Eight bacterial strains were isolated on kraft lignin (KL) containing mineral salt medium (L-MSM) agar with glucose and peptone from the sludge of pulp and paper mill. Out of these, ITRC-S8 was selected for KL degradation, because of its fast growth at highest tested KL concentration and use of various lignin-related low molecular weight aromatic compounds (LMWACs) as sole source of carbon and energy. The bacterium was identified by biochemical tests as Gram-positive, rod-shaped and non-motile. Subsequent 16S rRNA gene sequencing showed 95% base sequence homology and it was identified as Bacillus sp. In batch experiments, a decrease in pH was observed initially followed by an increase till it reached an alkaline pH, which did not alter the culture growth significantly. The bacterium reduced the colour and KL content of 500 mg l−1 KL in MSM, in the presence of glucose and peptone, at pH 7.6, temperature 30°C, agitation of 120 rpm and 6 days of incubation by 65 and 37% respectively. Significant reduction in colour and KL content in subsequent incubations is indicative of a co-metabolism mechanism, possibly due to initial utilization of added co-substrates for energy followed by utilization of KL as a co-metabolic. The degradation of KL by bacterium was confirmed by GC-MS analysis indicating formation of several LMWACs such as t-cinnamic acid, 3, 4, 5-trimethoxy benzaldehyde and ferulic acid as degradation products, which were not present in the control (uninoculated) sample. This favours the idea of biochemical modification of the KL polymer to a single monomer unit.  相似文献   

4.
In industry, fosfomycin is mainly prepared via chemical epoxidation of cis-propenylphosphonic acid (cPPA). The conversion yield of fosfomycin is less than 50% in the whole process and a large quantity of waste is produced. Biotransformation by microorganisms is an alternative method of preparation. This kind of conversion is more delicate, environmentally friendly, and the conversion yield of fosfomycin would be higher. In this work, an aerobic bacterium capable of transforming cPPA to fosfomycin was isolated. The organism, designated as strain S101, was identified as Bacillus simplex by morphological and physiological characteristics as well as by analysis of the gene encoding the 16S rRNA. Fosfomycin was assayed by two means, bioassay and gas chromatography (GC). Glycerol was a good carbon source for growth and cPPA conversion of strain S101. When cPPA was used as the sole carbon source, neither growth nor conversion to fosfomycin occurred. The optimum cPPA concentration in the conversion medium was 2,000 μg ml−1. After 6 days of incubation, the concentration of fosfomycin reached its maximum level (1,838.2 μg ml−1), with a conversion ratio of 81.3%. Air was indispensable for the growth but not for the conversion to fosfomycin. Furthermore, vanadium ions were found to be essential for the conversion. High concentrations of cPPA had fewer inhibitory effects on the growth of strain S101.  相似文献   

5.
Bacteria of the Bacillus species have been reported as an important microorganism in fermented soybean products. In the present study, thirty Bacillus isolates were screened from Meju, a Korean soybean fermentation starter. The comparative analysis of 16S rDNA sequences, 16S-23S internal transcribed spacer sequences, phenotypic, and biochemical characterizations revealed three phylogenetically distinct groups namely Bacillus atrophaeus, Bacillus polyfermenticus and Bacillus subtilis. The isolates were assayed for poly-γ-glutamate production and fibrinolytic activity. Among the isolates, B. polyfermenticus exhibited maximum poly-γ-glutamate production and fibrinolytic activity. Moreover, the soybean products fermented by B. polyfermenticus have increased the time taken for coagulation and hemorrhage in mice. The results of the present study clearly indicate the functional role of B. polyfermenticus in fermented soybean products.  相似文献   

6.
Growth of Ruta graveolens shoots was induced when Bacillus sp. cell lysates were added to the culture medium. Elicitation of coumarin by this lysate was also very effective; the concentrations of isopimpinelin, xanthotoxin and bergapten increased to 610, 2120 and 1460 μg g−1 dry wt, respectively. It also had a significant effect on the production of psoralen and rutamarin (680 and 380 μg g−1 dry wt) and induced the biosynthesis of chalepin, which was not detected in the control sample, up to 47 μg g−1 dry wt With lysates of the Pectobacterium atrosepticum, their effect on growth was not so significant and had no effect on the induction of coumarin accumulation. But elicitation with this lysate was much more effective for inducing the production of furoquinolone alkaloids; the concentrations of γ-fagarine, skimmianine, dictamnine and kokusaginine rose to 99, 680, 172 and 480 μg g−1 dry wt, respectively.  相似文献   

7.
Summary A heavy metal resistant bacterium, Bacillus circulans strain EB1 showed a high cadmium biosorption capacity coupled with a high tolerance to this metal when grown in its presence. Bacillus circulans EB1 cells grown in the presence of 28.1 mg cadmium/l were capable of removing cadmium with a specific biosorption capacity of 5.8 mg Cd/g dry wt biomass in the first 8 h. When the cells were pre-conditioned with low concentrations of cadmium in pre-grown medium, the uptake was increased to 6.7 mg Cd/g dry wt biomass. The maximum uptake of␣cadmium was during mid-logarithmic phase of growth. The resting cells (both wet and dry) of EB1 were also able to biosorb cadmium. Specific biosorption capacities of wet and dry biomass were 9.8 and 26.5 mg Cd/g dry wt biomass, respectively. Maximum cadmium removals by both wet and dry cells were at pH 7.0. The results showed that the cadmium removal capacity of resting cells was markedly higher than that of growing cells. Since both growing and resting cells had a high biosorption capacity for cadmium, EB1 cells could serve as an excellent biosorbent for removal of cadmium from natural environments.  相似文献   

8.

Background

Nattokinase (NK) is a serine protease enzyme of the subtilisin family. It exhibits a strong fibrinolytic activity. The fibrinolytic enzymes from Bacillus sp. have attracted interest as thrombolytic agents because of their efficiency in the fibrinolytic process including plasmin activation.

Methods

In the present study, VIT garden soil was collected and subjected to isolation process in order to screen for the NK production. Screening for NK enzyme was performed by radial caseinolytic assay. The production of NK enzyme was done in two different production medium for comparative studies. The NK enzyme was purified by gel permeation chromatography. The activity of the purified NK was checked by clot lysis and casein digestion assay. To investigate the structural basis of NK and fibrinogen interaction and also to identify the best binding mode, molecular dynamics and docking studies were performed.

Results

Based on the morphological and biochemical characterization, the isolate was identified as Bacillus sp. The overall purification fold of NK was about 3 with the specific activity of 664U/mg and 9.9% yield. Homogeneity of the purified enzyme was analyzed and confirmed by the single band obtained in SDS-PAGE. Molecular weight of the purified protease was estimated as 25 kDa. Purified NK enzyme exhibited 97% of effective clot lysis activity. The NK was docked in to the knob region of the fibrinogen at its binding site using Dock server. A total of 26 residues of fibrinogen and 29 residues of NK constitute the interface region. However, 9 residues of fibrinogen (THR238, MET264, LYS266, ARG275, THR277, ALA279, ASN308, MET310, and LYS321) and 8 residues of NK (GLY61, SER63, THR99, PHE189, LEU209, TYR217, ASN218, and MET222) are involved in intact binding.

Conclusions

A significant amount of NK enzyme was obtained from Bacillus sp. The docking analysis revealed that the NK and fibrinogen adopt an extended binding pattern and interacts with the crucial residues to exhibit their activity.
  相似文献   

9.
A bacterium, which was observed in all cultivations of Microcystis sp., was isolated and designated as Rhodococcus sp. KWR2. The growth of bloom-forming cyanobacteria, including four strains of Microcystis aeruginosa and Anabaena variabilis, was suppressed by up to 75–88% by 2% (v/v) culture broth of KWR2 after 5 days. But KWR2 did not inhibit eukaryotic algae, Chlorella vulgaris and Scenedesmus sp. An extracellular algicidal substance produced by KWR2 showed a cyanobactericidal activity of 94% and was water-soluble with a molecular weight of lower than 8 kDa.  相似文献   

10.
A novel gene (Ba-ega) of Bacillus sp. AC-1, encoding an endoglucanase (Ba-EGA), was cloned and expressed in Escherichia coli. Ba-ega, containing a 1,980-bp open reading frame (ORF), encoded a protein of 659 amino acids and had a molecular mass of 74.87 kDa. Ba-EGA was a modular enzyme composed of a family-9 glycosyl hydrolase catalytic module (CM9) and a family-3 carbohydrate-binding module (CBM3). To investigate the functions of the CBM3 and CM9, a number of truncated derivatives of Ba-EGA were constructed, and all were active. The catalytic module (rCM9) alone was less stable at high temperature than the recombinant Ba-EGA (rBa-EGA). The temperature stability for the complex of rCM9 and rCBM3 was still lower than rBa-EGA, but higher than rCM9 alone. These observations indicated the existence of a non-covalent interaction between CM9 and CBM3 that might strengthen the stability of CM9. However, this interaction is not strong enough to mimic the protective effect of the CBM in the wild-type enzyme.  相似文献   

11.
We report here the degradation of a pesticide, malathion, by Brevibacillus sp. strain KB2 and Bacillus cereus strain PU, isolated from soil samples collected from malathion contaminated field and an army firing range respectively. Both the strains were cultured in the presence of malathion under aerobic and energy-limiting conditions. Both strains grew well in the medium having malathion concentration up to 0.15%. Reverse phase HPLC–UV analysis indicated that Strain KB2 was able to degrade 72.20% of malaoxon (an analogue of malathion) and 36.22% of malathion, while strain PU degraded 87.40% of malaoxon and 49.31% of malathion, after 7 days of incubation. The metabolites mal-monocarboxylic acid and mal-dicarboxylic acid were identified by Gas chromatography/mass spectrometry. The factors affecting biodegradation efficiency were investigated and effect of malathion concentration on degradation rate was also determined. The strain was analyzed for carboxylesterase activity and maximum activity 210 ± 2.5 U ml−1 and 270 U ± 2.7 ml−1 was observed for strains KB2 and PU, respectively. Cloning and sequencing of putative malathion degrading carboxylesterase gene was done using primers based PCR approach.  相似文献   

12.
Summary An extracellular xylanase was purified to homogeneity from the culture filtrate of a thermophilic Bacillus sp. The molecular weight of the purified xylanase was 44 kDa, as analysed by SDS/PAGE. The enzyme reaction followed Michaelis–Menten kinetics with Kmapp and Vmax values of 0.025 mg/ml and 450 U/mg protein, respectively, as obtained from a Lineweaver–Burk plot. The xylanase contained no other enzyme activity except for the hydrolysis of xylan substrate. The optimal temperature of the enzyme assay was 50 °C. The optimum pH for the xylanase activity was at three peaks 6.5, 8.5 and 10.5, respectively and the enzyme was stable over a broad range of pH from pH 6 to 10.5. Metal ions tested with demetalized enzyme had no effect, with the exception of Hg2+ and Pb2+ (both strong inhibitors). Inhibition of the enzyme activity by N-bromosuccinimide (amino acid modifier) indicated the role of tryptophan residues in the catalytic function of the enzyme. Due to these outstanding properties, the xylanase of Bacillussp. finds potential applications in biopulping, biobleaching and de-inking of recycled paper and other industrial processes.  相似文献   

13.
Two repeated DNA sequences isolated from a partial genomic DNA library of Helianthus annuus, p HaS13 and p HaS211, were shown to represent portions of the int gene of a Ty3 /gypsy retroelement and of the RNase-Hgene of a Ty1 /copia retroelement, respectively. Southern blotting patterns obtained by hybridizing the two probes to BglII- or DraI-digested genomic DNA from different Helianthus species showed p HaS13 and p HaS211 were parts of dispersed repeats at least 8 and 7 kb in length, respectively, that were conserved in all species studied. Comparable hybridization patterns were obtained in all species with p HaS13. By contrast, the patterns obtained by hybridizing p HaS211 clearly differentiated annual species from perennials. The frequencies of p HaS13- and p HaS211-related sequences in different species were 4.3x10(4)-1.3x10(5) copies and 9.9x10(2)-8.1x10(3) copies per picogram of DNA, respectively. The frequency of p HaS13-related sequences varied widely within annual species, while no significant difference was observed among perennial species. Conversely, the frequency variation of p HaS211-related sequences was as large within annual species as within perennials. Sequences of both families were found to be dispersed along the length of all chromosomes in all species studied. However, Ty3 /gypsy-like sequences were localized preferentially at the centromeric regions, whereas Ty1/ copia-like sequences were less represented or absent around the centromeres and plentiful at the chromosome ends. These findings suggest that the two sequence families played a role in Helianthusgenome evolution and species divergence, evolved independently in the same genomic backgrounds and in annual or perennial species, and acquired different possible functions in the host genomes.  相似文献   

14.
A yellow pigmented bacterium designated strain MBLN094T within the family Flavobacteriaceae was isolated from a halophyte Salicornia europaea on the coast of the Yellow Sea. This strain was a Gram-stain negative, aerobic, non-spore forming, rod-shaped bacterium. Phylogenetic analysis of the 16S rRNA gene sequence of strain MBLN094T was found to be related to the genus Zunongwangia, exhibiting 16S rRNA gene sequence similarity values of 97.0, 96.8, 96.4, and 96.3% to Zunongwangia mangrovi P2E16T, Z. profunda SM-A87T, Z. atlantica 22II14-10F7T, and Z. endophytica CPA58T, respectively. Strain MBLN094T grew at 20?37°C (optimum, 25?30°C), at pH 6.0?10.0 (optimum, 7.0?8.0), and with 0.5?15.0% (w/v) NaCl (optimum, 2.0?5.0%). Menaquinone MK-6 was the sole respiratory quinone. The polar lipids were phosphatidylethanolamine, two unidentified aminolipids, and four unidentified lipids. Major fatty acids were iso-C17:0 3-OH, summed feature 3 (C16:1ω6c and/or C16:1 ω7c), and iso-C15:0. The genomic DNA G + C content was 37.4 mol%. Based on these polyphasic taxonomic data, strain MBLN094T is considered to represent a novel species of the genus Zunongwangia, for which the name Zunongwangia flava sp. nov. is proposed. The type strain is MBLN094T (= KCTC 62279T = JCM 32262T).  相似文献   

15.
A novel strain, DCY108T was isolated from soil of a Panax ginseng field, Yeoncheon province (38°04′N 126°57′E), Republic of Korea. Strain DCY108T is Gram-negative, non-motile, non-flagellate, rod-shaped, and aerobic. The bacterium grows optimally at 25–30 °C, pH 6.5–7.0 and 1 % NaCl. Phylogenetically, strain DCY108T is closely related to Pedobacter jejuensis JCM 18824T, Pedobacter aquatilis JCM 13454T, Pedobacter kyungheensis LMG 26577T and the type strain of the genus Pedobacter heparinus DSM 2366T. The DNA–DNA relatedness values between strain DCY108T and its close phylogenetic neighbors were below 30.0 %. The DNA G+C content of strain DCY108T was determined to be 45.1 mol%. The predominant quinone was menaquinone 7 (MK-7). The major polar lipids were identified as phosphatidylethanolamine and three unidentified aminolipids AL1, AL13 and AL17. Iso-C15:00, iso-C17:03OH and summed feature 3 (C16:1 ω7c/C16:1 ω6c) were identified as the major fatty acids present in strain DCY108T. The results of physiological and biochemical tests allowed strain DCY108T to be differentiated phenotypically from other recognized species belonging to the genus Pedobacter. Therefore, it is suggested that the newly isolated organism represents a novel species, for which the name Pedobacter panacis sp. nov is proposed with the type strain designated as DCY108T (=CCTCCAB 2015196T = KCTC 42748T).  相似文献   

16.
During antioxidant screening using 1,1-diphenyl-picrylhydrazyl (DPPH) and a lipid peroxidation assay, a streptomycete strain was found to produce herbimycin A and dihydroherbimycin A as antioxidants in the culture filtrate. These molecules were identified by using spectral analyses, including infrared, ultraviolet, mass spectrum, and nuclear magnetic resonance assays. In the DPPH radical-scavenging assay, dihydroherbimycin A exhibited more potent antioxidant activity (IC50, 1.3 μM) than α-tocopherol (IC50, 2.7 μM) that was used as a reference compound. In the lipid peroxidation assay, both herbimycin A and dihydroherbimycin A demonstrated antioxidant activities of 61% and 72%, respectively, at 100 μg/ml, while α-tocopherol exhibited an activity of 93% at the same concentration. Therefore, dihydroherbimycin A might have the potential to be developed into a new therapeutic agent.  相似文献   

17.
18.
A novel nicotine-degrading Pseudomonas sp. strain, HZN6, was isolated from a pesticide-wastewater treatment facility in Hangzhou. The strain could grow on nicotine as its sole source of carbon, nitrogen, and energy. The strain’s main intermediate metabolites were determined to be pseudooxynicotine, 3-succinoyl-pyridine (SP), and 6-hydroxy-3-succinoyl-pyridine (HSP). A Tn5 transposon mutant was generated in which the degradation pathway was blocked at the SP. A 4,583-bp DNA fragment flanking the transposon insertion site was obtained through self-formed adaptor PCR and analyzed. The mutant gene orfC displays 89% deduced amino acid sequence identity with the sirA-like gene (sirA2, a sulfurtransferase homologue gene) of Pseudomonas stutzeri A1501. The orfC-disrupted strain lost the ability to degrade SP, and the complementation strains with the orfC from the Pseudomonas sp. HZN6 and the sirA2 (PP_1233) from Pseudomonas putida KT2440 recovered the degradation ability. Though the orfC-disrupted strain also lost the xanthine dehydrogenase activity, the effects of tungsten on the degradation of SP and hypoxanthine revealed that the hydroxylation of SP to HSP was not a xanthine dehydrogenase type. These results demonstrated that the orfC gene was essential for the SP metabolism involved in the nicotine metabolic pathway in the Pseudomonas sp. HZN6 strain. This study might advance the understanding of the nicotine metabolic mechanism in Pseudomonas.  相似文献   

19.
Taxonomic studies were performed on three strains isolated from Cheonho reservoir in Cheonan, Korea. The isolates were Gram-negative, aerobic, rod-shaped, non-motile, catalase-positive, and oxidase-positive. Colonies on solid media were cream-yellow, smooth, shiny, and circular. Phylogenetic analysis of the 16S rRNA gene sequences revealed that these strains belong to the genus Flavobacterium. The strains shared 98.6–99.4% sequence similarity with each other and showed less than 97% similarity with members of the genus Flavobacterium with validly published names. The DNA-DNA hybridization results confirmed the separate genomic status of strains ARSA-42T, ARSA-103T, and ARSA-108T. The isolates contained menaqui-none-6 as the predominant menaquinone and iso-C15:0, iso-C15:0 3-OH, iso-Ci15:1 G, and iso-C16:0 3-OH as the major fatty acids. The genomic DNA G+C content of the isolates were 31.4–33.2 mol%. According to the phenotypic and genotypic data, these organisms are classified as representative of three novel species in the genus Flavobacterium, and the name Flavobacterium koreense sp. nov. (strain ARSA-42T =KCTC 23182T =JCM 17066T =KACC 14969T), Flavobacterium chungnamense sp. nov. (strain ARSA-103T =KCTC 23183T =JCM 17068T =KACC 14971T), and Flavobacterium cheonanense sp. nov. (strain ARSA-108T =KCTC 23184T =JCM 17069T =KACC 14972) are proposed.  相似文献   

20.
Kretzschmaria varians, a species apparently related to K. micropus, is described as new. It is distinguished primarily by having asci with 2 to 8 ascospores with inconstant germination slit length and remains of synnemata on stromata and surrounding substrate. Xylaria coremiifera, described here as new, bears small fragile coremia on pulvinate stromata and the surrounding substrate. Asci often have fewer than 8 ascospores, most frequently 4. Xylaria umbonata, described here as new, produces perithecia around a central umbo that appears to be the remains of a synnema. Ascospores have long spiralling germination slits.  相似文献   

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