Research Progress on the Polyphasic Taxonomy of Acetic Acid Bacteria / 微生物学通报

Acetic acid bacteria are Gram-negative,obligate aerobic bacteria that have the ability to incompletely oxidize alcohols or sugars to organic acids as end products. The taxonomy of acetic acid bacteria has undergone many changes in the last 30 years. The early classification systems for these bacteria were based on morphological and biochemical characteristics. Today,the acetic acid bacteria are classified as the consensus result of a polyphasic analysis,combining phenotypic,chemotaxonomic and genotypic data. This paper reviewed the polyphasic taxonomy of acetic acid bacteria,mainly introduced the current classification of acetic acid bacteria,then discussed the application of phenotypic,chemotaxonomic and genotypic method in the taxonomy of acetic acid bacteria.

Isolation and Identification of BLN-2 Producing Poly-?-Glutamic Acid and Studies on Its Solid-state Fermentation / 微生物学通报

A poly-?-glutamic acid producing strain--BLN-2, was isolated from the soybean products. According to the biochemical characteristics and 16S rRNA, the strain was identified as Bacillus subtilis. Using soybeans as culture, the solid-state fermentation conditions of BLN-2 have been studied. The results showed that the optimal carbon and nitrogen sources of BLN-2 were glucose, fructose, NaNO3 and KNO3, respectively. The orthrogonal experiments showed, when the final concentration of the fructose which was added to the soybean culture was 0.5%, the glucose, NaNO3 and KNO3 final concentraion were 2.0%, the production of ?-PGA was the highest--89.05 g/kg. It is 48.42% higher than other comparable soybean medium under the same conditions.

Screening and Identification of an Independent-glutamic Acid Strain Producing Poly (?-glutamic acid) / 微生物学通报

17 strains of bacterium that produced a large amount of ?-PGA when it was grown aerobically in a culture medium containing ammonium salt and sugar as sources of nitrogen and carbon respectively,were isolated from bean products.With the following identifications of colony morphology,physiological and biochemistry experiments,and genetics,the strain PGA-O-7 was classified as a Bacillus subtilis.The PGA production 2.8 (mg/mL) was obtained when it was grown in a medium containing 3% ammonium sulfate and 4% glucose at 30℃ for 72h with sharking.

The Concentration and Variation of Airborne Microbe in Guangzhou City / 微生物学通报

One year survey on the concentrations and monthly or seasonal variations of airborne microbe in Guangzhou city were analysed and studied with JWL-IIB airborne microbial sampler. The results showed that the yearly average airborne microbe content of outdoor was 2, 298 cfu/m3, and that of indoor was 1,792 cfu/m3 in Guangzhou city. The monthly variation range of outdoor airborne microbe was from 1,073 to 4,096 cfu/m3, the highest content was 4,096 cfu/m3 in March, and the lowest content was 1,073 cfu/m3 in October. The outdoor airborne bacteria and fungi counts were the highest in spring, next in summer, lower in winter and the lowest in autumn in the four seasons . The yearly average concentrations of outdoor airborne microbe at the Garbage compression station, the business walk street, the key traffic route, the residential area, the industrial district and the garden were 4, 573, 3, 835, 1, 580, 1,413, 1, 197 and 1, 187 cfu/m3respectively; and Ones of indoor at the key traffic route, the tourist three star-route hotel and the subway station were 2,511, 1,699and 1,167 cfu/m3 respectively . The study on airborne microbe can be used for the research of health prevention and environment control measures in Guangzhou .

Identification and Simulation Mutation of a High-productive Strain of Poly(?-glutamic acid) Independent of Glutamic Acid / 微生物学通报

A high productive poly ?-glutamic acid(?-PGA) strain PGA-N in a culture medium containing no L-glutamine was isolated from fermentation products.With the following identifications of colony mor-phology,physiological and biochemistry experiments,and genetics,the strain PGA-N was classified as a Bacillus licheniformis.According to the product environment,the base culture medium having no L-glutamine was simulated.In order to enhance the production of the strain PGA-N,the fermentation condi-tions,such as carbon source,nitrogen source,were optimized and the ?-glutamic acid production reached 5.16 g/L after getting the optimum formulation of this culture medium.PGA-N was mutagenized with com-bination of NTG and UV.A mutant PGA-N-C10 was screened which PGA production was increased from 5.16 g/L to 8.82 g/L.The study also investigated the effects of agitation speed on the cell biomass,?-PGA production and the ?-PGA molecular weight.The ?-PGA yield of PGA-N-C10 was as high as 11.00 g/L when the agitation speed was 400 r/min.