Physiologic Responses To Organic Solvent Stress Of Bacillus Cereus UD-8

As there is a wide range of research on the resistance of microorganism to toxic substances, incommon, the researches fall into two categories: antibiotics and solvents of antibacterial agents.It was the first time Inoue A group who raised the question of microorganism resistance to toxicsubstances, the paper entitled “Pseudomonas thrives in high concentrations of toluene” waspublished in1989of “Nature”. Many studies have shown that through the process ofmicroorganism contacting with solvent as ethyl alcohol, ethylene etc., formatted many defensemechanisms, such as changes in cell membranes, cell morphology, and the intracellulardegradation of the solvent pump, general stress response, in order to avoid subjecting these toxicinjury compounds. Most of studies are in the domain of Gram-negative bacterium, but itremains unclear that whether the mechanisms to important groups of industrial bacteria asGram-positive lactobacilli, clostridium, staphylococcus and Bacillus cereus are consistent withGram-negative bacterium, how it might enhance the mechanism of tolerance. Thoroughresearching on the mechanism of resistance to organic solvent tolerance extremophiles will helptransform and optimize relative performance of existing extremophiles, build new approachesand methods of adaptive reconstruction of solvent production toxic organic compoundsdegrading bacteria; in order to improve the physiological activity of these microorganisms in theenvironment, have a significant meaning for industrial applications.The paper research on physiologic responses to organic solvent stress and tolerantcharacteristic of Gram-positive organic solvent tolerant strain: Bacillus Cereus UD-8, the maincontent is:Research on Bacillus Cereus UD-8organic solvent tolerance property preliminarily showedits tolerance to high concentrations of benzene and ethyl alcohol, and superior tolerance tonormal hexane and methyl alcohol.To determine Bacillus Cereus UD-8membrane fatty acids, the results showed that saturationof membrane fatty acids rose substantially in the condition of organic solvent, TUFAs/TSFAshad reduced from36.565%to14.768%. But saturation of membrane fatty acids had declinedwith increasing the concentration of organic solvent. The study could confirm that BacillusCereus UD-8enhances the saturation of membrane fatty acids to reduce cell membrane mobilitycaused by cell membrane oppression and enhances its tolerance to organic solvent in themeantime.To determine Bacillus Cereus UD-8antimicrobial resistance the results showed that a10μg/mL concentration of antibiotic has a relatively lesser inhibitory effect to biomass growthaveragely, but Bacillus Cereus UD-8showed its high rate of antimicrobial resistance to the otherthree varieties of tetracycline, the results were similar with research on E.coli JA300by Aono,so there might be mechanisms of Bacillus Cereus UD-8efflux pumps according to a preliminaryinspection.To measure cells surface hydrophobicity in different types and concentrations of organicsolvent. The surface hydrophobicity of Bacillus Cereus UD-8differed depending on bothdifferent types and different concentrations, modestly and irregularity. The enhanced toleranceto organic solvent of Bacillus Cereus UD-8is not caused by reducing surface hydrophobicity.Bacillus Cereus UD-8cells became smaller and shrinkage under organic solvent stress. Two conditions occurred with increase of concentration, cells were distorted acutely by benzene andnormal hexane, however cell volumes were increased by elevatory concentration of organicsolvent, Bacillus Cereus UD-8can enhance tolerance to organic solvent by enlarging volumeand reducing specific surface area.