Isolation of New Strains of Bacteria Able to Synthesize 1,3-Propanediol from Glycerol

The natural environment is inhabited by many species that exhibit very specific metabolic activities that may find industrial applications. The aim of the study was to select non-pathogenic cultures of bacteria of the genus Clostridium and lactic acid bacteria able to convert glycerol into 1,3-propanediol (1,3-PD). Another aim of this study was to identify the isolates that best produced 1,3-propanediol both from pure and crude glycerol. The most efficient strains identified (Cl. butyricum) were analysed on a bioreactor scale. The aim was to determine temperature conditions on the efficiency and duration of 1,3-PD synthesis. The species Clostridium were identified using amplification of the 16S rRNA coding sequence. A total of 123 isolates (of the genus Clostridium and lactic acid bacteria) were isolated;a vast majority of these were able to synthesize 1,3-PD. The best results were obtained for Cl. butyricum strain DSP1, which was isolated from the rumen of a cow fed with glycerol. The strain efficiency using pure glycerol on bioreactor scale 0.65 mol/mol of glycerol at a temperature of 38℃ and a constant pH of 7.0.

Characterization of Class 1 Integron Gene Cassettes among Clinical Bacteria Isolated from One Large Hospital in Northern China

The class 1 integron and complex gene cassettes among different species of clinical isolates in northern China were characterized in this study. 383 clinical isolates were obtained from northern China, and class 1 integrons containing gene cassettes widely distributed among gram negative clinical isolates was observed. We find that the class 1 integron showed positive correlation with multidrug resistance phenotype of gram negative bacteria. In addition, we find that isolates belonged to one species harbored different types of gene cassette arrays, while same types of gene cassette arrays were observed in different species of isolates. The diversity of gene cassette arrays among the isolates indicated the complexity of multidrug resistance in clinical isolates in northern China.

Antimicrobial Profile of Lactic Acid Bacteria Isolated from Vegetables and Indigenous Fermented Foods of India against Clinical Pathogens Using Microdilution Method

In dairy and food industries lactic acid bacteria （LAB） have been used in form of starter culture that plays vital role in fermentation; as flavouring and texturizing or as preservative agents. There is increasing evidence that lactobacilli which inhabit the gastrointestinal tract develop antimicrobial activities and participate in the host＇s defence system[1]. During fermentation, most of the LAB produces a number of different compounds like organic acids, hydrogen peroxide, diacetyl, acetaldehyde, carbon dioxide, polysaccharides, and proteinaceous compounds called bacteriocins or bacteriocinogenic peptides.

Screening of Antagonistic Bacteria from Phyllosphere towards Tobacco Brown Spot Fungus Alternaria alternata

The possibility of employing antagonistic bacteria for the control of tobacco brown spot was studied. Approximately 136 strains of bacteria were isolated from phyllospheres of tobacco and 9 of these possessed high levels of antagonistic properties, They significantly reduced brown spot in detached tobacco leaves when artificially inoculated with Alternaria alternata. Culture filtrate of the most effective bacterial isolate which designated as Tpb88 was shown to be very efficient in inhibiting mycelial growth of A alternata in dual cultures. Culture filtrate of Tpb88 inhibited germination and germ tube elongation of A alternata. The results showed that the culture filtrate directly inhibited spore germination of A alternata, especially during the first hours of the paired cultivation. The rate of antagonistic activity of culture filtrate of Tpb88 depended on its concentration in the mixture. The greatest inhibition of spore germination was ob served at the highest concentration of filtrate （filtrate to fungal spores inocula mixed in proportion 1 ： 50）. These suggest that the hypothetic mechanism of Tpb88 against tobacco brown spot is to produce antagonistic substances.

Identification and Susceptibility Test of Ralstonia solanacearum Isolated from White Burley

[ Objective ] The paper was to isolate and identify Ralstonia solanacearum from white burley, and determine its susceptibility to 6 fungicides. [ Mcth- od] Using the combination method of semiselective medium （PCCG） and apolymerase chain reaction （PCR） technique, R. solanacearum in stalk of white burley from Dazhou City in Sichnan Province was isolated, and its biochemical type was identified. Through susceptibility test, the susceptibility of R. solanacearum to bismerthiazol, ethylicin, streptomycin, lime sulfur, 47% polylysine, 99% kojic acid was studied in laboratory. [Result] A total of 23 strains OfR. solanacearum were isolated, all belonging to biochemical type Ill. R. solanacearum obtained in the test were more susceptible to ethylicin, streptomycin and bismerthiazol, and ethylicin had good control effect against R. solanacearum with ECso of 0.086 ml/L. [ Conclusion ] The study provide theoretical basis for control of R. solanaceanon in white burley.

Bacillus Licheniformis Dhs-40, a Flocculating Active Strain and Its Flocculating Activity

Microbial flocculants have become a hot spot in recent years. A bacterial strain with high flocculating activity was isolated from seawater samples. The strain was defined as Bacillus licheniformis dhs-40 by 16S rDNA identification and Biolog test. Ultrasonication test confirmed the flocculating activity of the strain was both in fermentation supernatant and cell. According to flocculating activity curve, the ideal fermentation time for collecting flocculating active substances was two days. The flocculating activity of the strain was sensitive to pH. The strain could only preserve flocculating activity while pH varied from 7 to 11. However, it could preserve flocculating activity while temperature varied from -20℃to 100 ℃ Saccharide, protein, lipid, nucleic acids qualitative test and RNase, Proteinase K treatment confirmed the flocculating active substances were proteins. Their flocculating activities were insensitive to Proteinase K.