Pattison T L, Geornaras I, von Holy A
Department of Microbiology, University of the Witwatersrand, South Africa.
Int J Food Microbiol. 1998 Aug 18;43(1-2):115-22. doi: 10.1016/s0168-1605(98)00103-2.
Microbial populations of 46 commercially produced sorghum beer samples from retail outlets in Johannesburg, South Africa, were enumerated and characterized. Aerobic plate counts, lactic acid bacteria counts and yeast counts were performed by conventional and Petrifilm plating. Conventional methods yielded yeast counts of 7.84 log CFU/ml, lactic acid bacteria counts of 6.44 log CFU/ml and aerobic plate counts of 5.96 log CFU/ml. In comparison, Petrifilm counts were 7.85 log CFU/ml for yeasts, 5.31 log CFU/ml for lactic acid bacteria and 5.34 log CFU/ml for aerobic bacteria. Characterization of 419 predominant bacterial isolates from Standard One Nutrient Agar, MRS Agar and corresponding Petrifilm plates yielded 88.0% lactic acid bacteria, 8.4% Bacillus species, 2.9% Micrococcus species and 0.7% Gram negative bacteria. Composition of predominant lactic acid bacteria populations from Standard One Nutrient Agar and both types of Petrifilm plates showed marginal differences. Increased proportions of heterofermentative lactic acid bacteria were, however, isolated from conventional MRS Agar compared to the modified Petrifilm product which represented the equivalent to MRS Agar.
对来自南非约翰内斯堡零售店的46个商业生产的高粱啤酒样品的微生物菌群进行了计数和表征。通过传统平板培养法和Petrifilm平板计数法进行需氧平板计数、乳酸菌计数和酵母计数。传统方法得到的酵母计数为7.84 log CFU/ml，乳酸菌计数为6.44 log CFU/ml，需氧平板计数为5.96 log CFU/ml。相比之下，Petrifilm计数法得到的酵母计数为7.85 log CFU/ml，乳酸菌计数为5.31 log CFU/ml，需氧菌计数为5.34 log CFU/ml。对来自标准一号营养琼脂、MRS琼脂和相应Petrifilm平板的419株主要细菌分离株进行表征，结果显示乳酸菌占88.0%，芽孢杆菌属占8.4%，微球菌属占2.9%，革兰氏阴性菌占0.7%。标准一号营养琼脂和两种Petrifilm平板上主要乳酸菌菌群的组成显示出微小差异。然而，与代表相当于MRS琼脂的改良Petrifilm产品相比，从传统MRS琼脂中分离出的异型发酵乳酸菌比例有所增加。
