The effect of the lactic acid bacteria culturing conditions on their antagonistic activity to pathogens of tuberculosis

It has been found that the antagonistic activity of lactic acid bacteria depends on the composition of the nutrient medium and the temperature of culturing. It has been shown that the best antimicrobial effect to mycobacteria is achieved by the cultivation of lactic acid bacteria on the MRS nutrient media and a combined nutrient medium with the use of lactulose or glucose as a source of carbon. The optimum temperature for culturing an association of lactic acid bacteria for achieving high antagonistic activity to mycobacteria is 300C, and the duration of cultivation is 24 hours.

STUDY ON CULTURE CONDITION OF MARINE VITAMIN B_(12)-PRODUCING BACTERIA / 中国海洋药物

The vitamin B 12 Productivity of 14 marine bacterial strains isolated from the China Sea was determined microbiologically using Escherichia coli 113 3. Tests were made on the culturing media and culture conditions for Vitamin B 12 production. The results showed that the culturing medium in which the extract from soybean cake with seawater and some nutriments were added was suitable to recognize further some marine Vitamin B 12 producing bacterial strains. The medium with appropriate cobalt chloride and some salts added may be useful for Vitamin B 12 biosynthesis. The PH value of the fermentation for the testing strains was raised with the lapse of time for fermentation. A better Vitamin B 12 production may be obtained by keeping the fermentation liquid slightly basic till about 96h. No.2627 strain in all the strains tested showed well in the productivity. The mixed cultivation of some strains (including No.2627 strain) tested often has potentiality and superiority for Vitamin B 12 production.

Selection of De-emulsification Strains and Optimization of Fermentation Conditions / 微生物学通报

Petroleum-field emulsions,which are produced in the process of exploration,production and re-covery,represent a major environmental and processing problem for the petroleum industry.Biological de-mulsifier as a biological agent,will become a novel method of petroleum-field emulsions demulsifier instead of chemical demulsifier for its high efficiency,low cost,high adoptability,environment-friendly,repeated use.A set of high efficiency and convenient method was established to isolate de-emulsification strain and studied on the fermentation conditions of the de-emulsification strains.A de-emulsification strains,isolated from a petroleum-contaminated site,was evaluated for its de-emulsification capabilities using a kero-sene/water model emulsion system keeping stable for more than 200 hours which was mixed by stirring Tween 60-water(0.072%,V/V)and Span 60-oil(0.028%,V/V)at the ratio(oil:water)of 6.5:3.5.We have isolated two strains with high and steady de-emulsification activity by separation and purification,blood-plate test,excluding-oil test and de-emulsifying test.The average de-emulsification rates were more than 80.0% at 24 h.The two strains are both belonging to bacillus by traditional and molecular genetic iden-tification.By optimizing the demulsification bacteria fermentation conditions,the fermentation conditions,which is the most suitable for accumulating the fermentation products,were determined as follows:tem-perature 25?C,stirring speed160 r/min,pH 9,inoculated quantities 20%.When the fermentation conditions were temperature 35?C,stirring speed120 r/min,pH 9,inoculated quantities 2%,the fermentation products appeared the highest activities of demulsification.