Lactic Acid Bacteria In Samples Research Articles

Isolation and Identification of Yeasts and Lactic Acid Bacteria from Local Traditional Fermented Camel Milk, Chal

The yeasts and lactic acid bacteria in samples of the Iranian traditional fermented camel milk, Chal were identified on the basis of physiological and morphological properties. Yeast species were identified including Pichia. anamala, Pichia. jadinii, Debaryomyces. hansenii, Pichia. guilliermondii, Kluyvermyces. marxianus, Candida. fermentati, Pichia. ciferrii, Torulospora. delbrueckii, Candida. versatilis, Kluyvermyces. lactis, Candida. kefir, Saccharomyces. pastorianus, Saccharomyces. serevisiae, Candida. friedrichii, Kluyvermyces. polysporus, Rhodotorula. musilaginosa, Candida. lipolytica and Candida. lusitaniae. All of them could assimilate the glucose and liquefacted the gelatin, but could not production starch, tolerated 1% acetic acid, growth in the presence of Nacl 16% (except Debaryomyces. hansenii), anassimilateed the nitrat (except Rhodotorula. musilaginosa). Within the yeasts species, Kluyvermyces. lactis (8.57%) and Kluyvermyces. marxianus (8.57%) were the predominant. Also 93 different lactic acid bacteria species were identified including 64 bacilli as lactobicallus and wieselia, 8 cocci, leuconostoc, 11 coccobacili, leuconostoc, lactococcus and wieselia, 2 streptococci, streptoccus and 8 tetrad cocci shapes, pediococci. All isolates fermented galactose, except Lactobacillus delbrueckii subsp. Bulgaricus, Lactobacillus kefir, Lactobacillus viridescens. All the isolates could growth at 37°C, only Leuconostoc mesenteroides subsp. Cremoris and Leuconostoc paramesenteroides could not growth at 30°C. This study revealed Chal contained a wide variety of yeasts and lactic acid bacteria.

Growth of Listeria monocytogenes, Aeromonas hydrophila and Yersinia enterocolitica on cooked beef under refrigeration and mild temperature abuse

Strains of the cold-tolerant bacteria Listeria monocytogenes, Aeromonas hydrophila and Yersinia enterocolitica were inoculated onto samples of cooked beef and incubated at 5 and 10°C under both aerobic and vacuum-packaged (anaerobic) conditions. These organisms were enumerated over a time course and data were analysed to give values for the generation and lag times. All species grew well under all conditions except for A. hydrophila at 10°C under anaerobic conditions where inhibition by lactic acid bacteria may have occurred. Growth rates were similar for L. monocytogenes and A. hydrophila whether the samples were stored aerobically or anaerobically, but Y. enterocolitica grew more slowly under anaerobic conditions. However, the growth of lactic acid bacteria in samples stored aerobically indicated that metabolic activity resulted in the formation of anaerobic conditions during the incubation period. Growth rates predicted by response surface models and measured growth rates were not in agreement for L. monocytogenes or A. hydrophila, but similar comparisons for Y. enterocolitica showed good agreement.