ABSTRACT
Objective To construct sigF deletion mutant of Bacillus anthracis and the complementary strain of sigF deletion mutant in order to analyze the effect of losing sigF on formation of spores.Methods The spectinomycinadenyltransferase gene(spc) was inserted to replace sigF of B.anthracis by homologous recombination.A plasmid which contained sigF and sigF promotor was constructed and then transferred to the mutant to get a complementary strain of sigF deletion mutant.The characters of the mutant were analyzed by measuring growth curves, the ability of carbohydrate metabolism was compared, and spore formation was observed under a microscope.Results The sigF deletion strain A16D2△sigF was constructed from A16D2,which had a similar growth rate to the wild type A16D2 in logarithmic phase, but was not significantly different from the initial strain in the ability to use carbohydrates,although unable to form spores.The strain was found to maintain the state of asymmetric division by microfluidics experiment.Conclusion It is showed by this study that sigF is the essential gene of B.anthracis for spore formation, but not essential for vegetative growth.
ABSTRACT
Objective To compare the separation effects of protein samples extracted by two different methods with two -dimensional gel electrophoresis (2-DE) .Methods Ultrasonic disruption and glass-beads grounding were used to prepare protein samples of Gram-negative bacteria , Gram-positive bacteria and animal tissues .The actual results of the two sample preparation methods were compared by 2-DE.Results The 2-DE maps of samples extracted by the two methods were obtained.Conclusion The 2-DE maps of glass-beads grounding samples are better than those of ultrasonic disruption thanks to their lower backgrounds , which are beneficial for further image analyses .
ABSTRACT
A spore is another life cycle form of Bacillus anthracis for resisting starvation.When conditions are favorable for growth, the dormant spore will germinate,go through outgrowth, and are ultimately converted back into a growing cell. As the first step back to vegetative growth, germination could be induced by nutrients and a variety of non-nutrient agents. Nutrient germinants trigger cation release and water absorption by binding to receptors in the spore′s inner membrane.Then the spore′s peptidoglycan cortex is hydrolyzed and the spore core rehydrates, which allows the resumption of spore metabo-lism and macromolecular synthesis.This paper reviews the nutrient germinant receptor and cortex lytic enzymes in the spore germination process of B.anthracis.
ABSTRACT
Objective To explore the function of gene phoN1 in Shigella flexneri.Method Using the λ-Red recombi-nant system, phoN1was knocked out from S.flexneri 2a strain 301.Comparative proteomics was performed to analyze the differences between mutant and wild-type strains in protein expression profiles .Sereny tests and competitive infection assays were carried out to compare the virulence of mutant and wild-type strains .Results The deletion mutant of phoN1 was suc-cessfully constructed .No significant difference between the two strains was found in the comparative proteomics analyses . The function of gene phoN1 might be unrelated to the invasion ability of S.flexneri according to the results of Sereny tests and competitive infection assays .Conclusion Gene phoN1 might be of no use for the in vitro survival and host cell invasion of S.flexneri.