Construction and secretory expression of beta-galactosidase gene from Lactobacillus bulgaricus in Lactococcus lactis.

Objective: This study is to examine the secretion effects of beta-galactosidase in Lactococcus lactis.

Methods: The usp45 and beta-galactosidase genes were cloned and inserted into plasmid pMG36e to obtain the recombinant plasmid pMG36e-usp-lacZ. This recombinant plasmid was transformed into both Escherichia coli DH5alpha and L.

Analysis of β-galactosidase production and their genes of two strains of Lactobacillus bulgaricus.

A bacterial β-galactosidase delivery system is a potential therapy for lactose intolerance. Currently, two Lactobacillus bulgaricus strains with different biological characteristics are under consideration as potential sources. However, differences in these β-galactosidase genes and their resulting production levels are poorly characterized.

[Construction and property study of recombinant Lactococcus lactis with non-fusion expressing of beta-galactosidase].

Objective: To construct recombinant Lactococcus lactis strains exhibiting high beta-galactosidase activity in non-fusion way, and study their enzyme activities and enzyme secretion rates.

Methods: The recombinant plasmids pMG36e-lacZ 1.1480 and pMG36e-lacZ wch9901 which could express beta-galactosidase from Lactobacillus delbrueckii subsp.

Non-fusion and fusion expression of beta-galactosidase from Lactobacillus bulgaricus in Lactococcus lactis.

Objective: To construct four recombinant Lactococcus lactis strains exhibiting high beta-galactosidase activity in fusion or non-fusion ways, and to study the influence factors for their protein expression and secretion.

Methods: The gene fragments encoding beta-galactosidase from two strains of Lactobacillus bulgaricus, wch9901 isolated from yogurt and 1.1480 purchased from the Chinese Academy of Sciences, were amplified and inserted into lactococcal expression vector pMG36e.

[Beta-galactosidase gene from Lactobacillus delbrueckii subsp. bulgaricus gets non-fusion expression in Escherichia coli].

Objective: To construct the food-grade recombinant probiotic strain with high activity beta-galactosidase, the beta-galactosidase gene (lacZ)from Lactobacillus delbrueckii subsp. bulgaricus was in non-fusion expressed in Escherichia coli.

Methods: From Lb.

[Phylogeny analysis and identification of two bacterial strains sourcing from human intestine and having resistance to acid and bile].

Objective: To screen bacteria for the engineering bacteria expressing and secreting high activity beta-galactosidase, and two bacterial strains called as R92-2 and R111 with acid and bile resistances would be isolated from health human intestine to strain identification and phylogenetic analysis.

Methods: These two strains were first been identified with phenotype characteristic analysis. Then the 16S rDNAs of these two bacterial strains were amplified and sequenced with the primers designed by the conserve sequences.

[Comparative study of the resistance of bacteriophageT4, PhiX174D, MS2 and f2 to gamma radiation].

Objective: To screen the suitable bacteriophage as virus indicator in irradiation sterilization.

Methods: Suspensions of bacteriophage T4, phiX174D, MS2, and f2, Escherichia coli 8099, and Bacillus subtilis var.niger.

[Comparative study on the resistance of Bacteriophage phi chi 174D, T4 and f2 to an iodophor in laboratory].

Background: To screen for the most resistant bacteriophage as indicator in disinfection tests, the resistance of bacteriophage phi chi 174D, T4 and f2 to iodophor were observed in laboratory.

Methods: The virucidal activity of iodophor against bacteriophage phi chi 174D, T4, and f2 were assessed by suspension test. The neutralizer is selected and appraised by testing with neutralizer.

[Comparison on resistance of bacteriophages to sodium dichloroisocyanurate in laboratory].

Objective: To scan the most resistable bacteriophage as an indicator in disinfection tests, and to study the resistance of bacteriophage T4, Phichi 174D, and f2 to the sodium dichloroisocyanurate (NaDCC) in laboratory.

Methods: The virucidal activity of NaDCC against bacteriophage T4, Phichi 174D, and f2 were assessed by suspension test. The neutralizer was selected and be appraised by test of neutralizer.

[A comparative study on the resistance of bacteriophage T4, phiXM174D, and f2 to glutaraldehyde in laboratory].

Objective: To identify the best indicative bacteriophage in disinfection tests through comparing the resistance of bacteriophage T4, phiX174D, and f2 to glutaraldehyde.

Methods: The virucidal activities of glutaraldehyde against bacteriophage T4, phiX174D, and f2 were assessed with suspension tests along with neutralizer tests. The double-agar-layer plaque technique was used to detect the bacteriophage T4, phiX174D, and f2.

[Construction and expression of Neisseria surface protein (nspA) of Neisseria gonorrhoeae in Escherichia coli].

Objective: To construct neisseria surface protein (NspA) recombinants of Neisseria gonorrhoeae from a reference strain and express this protein in E. coli.

Methods: The fragments of NspA gene of Neisseria gonorrhoeae was amplified by PCR from the reference strain genomic DNA and cloned into expression vector pET-30c (+) to get the pET-NspA recombinants.

[Quantitative analysis of dominating intestinal flora among groups of people with different body fat].

Objective: To investigate the alteration of dominating intestinal floras among groups of people with different body fat and probe into the possible effect on lipid metabolism.

Methods: According to the BMI values, subjects were divided into 4 groups, including fleshless group, normal group, overweight group and obese group. Five dominating floras of all fresh stools were quantitated using selective culture method, and all data were analyzed statistically.

[Relief effect of beta-galactosidase genetically engineered lactococcus lactis on the cell toxicity caused by lactose].

Objective: To assess the relief effect of beta-galactosidase genetically engineered Lactococcus lactis on the cell toxicity caused by lactose in vitro.

Methods: An in vitro toxic Caco-2 cell model caused by lactose was established to evaluate the relief effect of beta-galactosidase genetically engineered Lactococcus lactis. Cell morphological parameters and proliferation activity parameter were used.

Comparison of susceptibilities of M. tuberculosis H37Ra and M. chelonei subsp. abscessus to disinfectants.

Objective: To determine the susceptibilities of M. tuberculosis H37Ra and M. chelonei subsp.

[Study of the genetic stability of expression plasmid vector pMG36e in host bacteria].

Objective: To study the genetic stability of expression plasmid vector pMG36e in Escherichia coli JM109 and Lactococcus lactis MG1363/36e and observe the effect of erythomycin for its stability.

Methods: We used classical method to determine the genetic stable rates of pMG36e in E. coli JM109 and Lactococcus lactis MG1363/36e with or without erythomycin selective pressure.

[A follow-up study on dietary factors of kidney stones in Bao'an district, Shenzhen City].

Objective: To evaluate the major dietary factors of kidney stones in Bao'an District of Shenzhen City and provide a scientific base for further effective prevention of kidney stones.

Methods: Following the process of stratified cluster random sampling in Bao'an district, a cross-sectional study (July-Aug, 2000) was conducted for collecting the base-line data on kidney stones from a population of permanent residents who were over 15 years old, exclusive of those who had had kidney stones or could not correctly respond to the questionnaire review. Then, a follow-up survey (July-Sept, 2002) for incident kidney stone cases was carried out among those residents.

[Amplification of Lactobacillus bulgaricus beta-galactosidase gene and optimization of the reaction condition].

Objective: To obtain the gene which encode high activity beta-galactosidase from Lactobacillus bulgaricus and study the influencing factors of amplification.

Methods: Lysozyme and freeze-thaw cycles were applied to obtain Lactobacillus bulgaricus DNA; different template concentration and annealing temperature were selected for the amplification.

Results: 60 ng/microliter template concentration and 66 degrees C annealing temperature were the best reaction conditions of amplifying the gene.