Production and partial characterization of chitinase from a halotolerant Planococcus rifitoensis strain M2-26

peer reviewedThis paper is the first to investigate the production and partial characterization of the chitinase enzyme from a moderately halophilic bacterium Planococcus rifitoensis strain M2-26, earlier isolated from a shallow salt lake in Tunisia. The impact of salt, salinity concentration, pH, carbon and nitrogen sources on chitinase production and activity have been determined. This is the first report on a high salt-tolerant chitinase from P. rifitoensis, since it was active at high salinity (from 5 to 30% NaCl) as well as in the absence of salt. This enzyme showed optimal activity at 70 C and retained up to 82 and 66% of its original activity at 80 or 90 C, respectively. The activity of the enzyme was also shown over a wide pH range (from 5 to 11). For characterization of the enzyme activity, the chitinase secreted in the culture supernatant was partially purified. The preliminary study of the concentrated dialysed supernatant on native PAGE showed at least three chitinases produced by strain M2-26, with highest activity approximately at 65 kDa. Thus, the thermo-tolerant and high salt-tolerant chitinases produced by P. rifitoensis strain M2-26 could be useful for application in diverse areas such as biotechnology and agro-industry

A Chitinase from Aeromonas veronii CD3 with the Potential to Control Myxozoan Disease

Background: The class Myxosporea encompasses about 2,400 species, most of which are parasites of fish and cause serious damage in aquaculture. Due to the concerns about food safety issues and limited knowledge of Myxozoa life cycle and fish immune system, no chemicals, antibiotics or immune modulators are available to control myxozoa infection. Therefore, little can be done once Myxozoa establishment has occurred. Methodology/Principal Findings: In this paper we isolated Aeromonas veronii CD3 with significant myxospore shell valvedegrading ability from pond sediment. A 3,057-bp full-length chitinase gene was consequently cloned, and the corresponding mature, recombinant chitinase (ChiCD3) produced by Escherichia coli had substantial chitinase activity. The deduced sequence of ChiCD3 contained one catalytic domain, two chitin-binding domains, and one putative signal peptide. ChiCD3 had an optimal activity at 50uC and pH 6.0, and retained more than 50 % of its optimal activity under warm water aquaculture conditions (,30uC and pH,7.0). After incubation with ChiCD3, 38.064.8 % of the myxospores had damaged shell valves, whereas myxospores incubated with commercially available chitinases remained intact. Conclusion/Significance: This study reveals a new strategy to control myxozoan disease. ChiCD3 that has capacity to damage the shell valve of myxospores can be supplemented into fish feed and used to control Myxozoa-induced disease

Monitoring of microbial hydrocarbon remediation in the soil

Bioremediation of hydrocarbon pollutants is advantageous owing to the cost-effectiveness of the technology and the ubiquity of hydrocarbon-degrading microorganisms in the soil. Soil microbial diversity is affected by hydrocarbon perturbation, thus selective enrichment of hydrocarbon utilizers occurs. Hydrocarbons interact with the soil matrix and soil microorganisms determining the fate of the contaminants relative to their chemical nature and microbial degradative capabilities, respectively. Provided the polluted soil has requisite values for environmental factors that influence microbial activities and there are no inhibitors of microbial metabolism, there is a good chance that there will be a viable and active population of hydrocarbon-utilizing microorganisms in the soil. Microbial methods for monitoring bioremediation of hydrocarbons include chemical, biochemical and microbiological molecular indices that measure rates of microbial activities to show that in the end the target goal of pollutant reduction to a safe and permissible level has been achieved. Enumeration and characterization of hydrocarbon degraders, use of micro titer plate-based most probable number technique, community level physiological profiling, phospholipid fatty acid analysis, 16S rRNA- and other nucleic acid-based molecular fingerprinting techniques, metagenomics, microarray analysis, respirometry and gas chromatography are some of the methods employed in bio-monitoring of hydrocarbon remediation as presented in this review

Novel microorganisms for the treatment of Ni and V as spent catalysts

370-379Oil refining industry has used a great amount of catalysts, which once exhausted due to metal and hydrocarbon poisoning are disposed in special confining sites. Catalyst disposal represents a serious environmental problem due to the potential risk of metal leaching by natural events. The necessity to treat great amounts of catalysts and the existence of microorganisms that coexist with metals suggest that microorganisms can be used for the treatment of hazardous wastes such as spent catalysts. The aim of the present study was to isolate microorganisms from rich metal sites, mines, soils and water from rivers close to mines and then evaluate their ability to remove Ni and V from spent catalyst. Twenty-six isolates were obtained from samples using 9K liquid media and from them, only twelve isolates presented a minimum inhibitory concentration (MIC) higher than 200 ppm of Ni and V, then were evaluated for their ability to remove Ni and V in 9K liquid media added with 16% (w/v) pulp density of the catalyst. Results showed that isolates MNSH1-9K-1 and PRGSd-9K-4 had the highest removal for Ni and V corresponding to 149.5 mg Kg-1 and 920.5 mg Kg-1, respectively and were identified by sequencing of 16S ribosomal RNA gene as Bacillus megaterium and Bacillus subtilis, respectively

Identification of Bacillus megaterium and Microbacterium liquefaciens genes involved in metal resistance and metal removal

Bacillus megaterium MNSH1-9K-1 and Microbacterium liquefaciens MNSH2-PHGII-2, two nickel-vanadium resistant bacteria from mine tailings located in Guanajuato, Mexico, are shown to have the ability to remove 33.1% and 17.8% of Ni and 50.8% and 14.0% of V, respectively, from spent petrochemical catalysts containing 428 ± 30 mg kg-1 of Ni and 2165 ± 77 mg kg-1 of V. In these strains, several Ni resistance determinants were detected by conventional PCR. The nccA (Ni-Co-Cd resistance) was found for the first time in B. megaterium. In M. liquefaciens the above gene and, additionally czcD gene (Co-Zn-Cd resistance) and a high-affinity nickel transporter were detected for the first time. This study characterizes the resistance of M. liquefaciens and B. megaterium to nickel through the expression of genes conferring metal resistance.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author