Biochemical and physiological properties of lactic acid bacteria isolated from different kefir grains

In this study, it was aimed to determine the biological properties of Caucasian and Kyrgyz kefir types obtained from Afyonkarahisar, Ankara, and Izmir regions and the lactic acid bacteria species in kefir grains in order to create a local and cultural archive and compare with the information in the literature. 6 lactic acid bacteria from Afyonkarahisar region, 25 lactic acid bacteria from Izmir region, and 50 lactic acid bacteria from Ankara region were studied. The growth rates of the isolated lactic acid bacteria showed an average growth rate of 100% at 10oC, 89% at 4% salt concentration, and mostly in the pH range of 5.0 - pH range of 6.0. As a result of the study, it was determined that the most isolated lactic acid bacteria species in Afyon, Ankara and Izmir regions was Lactobacillus species with rates of 50%, 86% and 69.57%, respectively. When all the isolated bacteria are considered, the most isolated lactic acid bacteria strain is Lactobacillus with a rate of 75.28%, while the least isolated lactic acid bacteria is Bifidobacterium with a rate of 1.12%. Other lactic acid bacteria strains were found to be 44.49% for Lactococcus, 15.73% for Streptococcus, and 3.37% for Leuconostoc. Later, the diagnoses were confirmed with API test kits for the test isolates. As a result of the analyzes, it was seen that all of the isolated lactic acid bacteria species were gram positive and catalase negative, while 51% of them had positive urease activity. It was determined that the temperatures with the highest growth rates were 10oC and 37oC. When the growth was examined at 4 different salt concentrations, it was determined that the highest growth rate was 4% and then 6%. The sugar with the highest gas formation rate from sugar fermentation is galactose with a rate of 17%. The sugar types with the highest turbidity are maltose, lactose, and glucose with rates of 55%, 54%, and 53%, respectively. For 9 sugar types, gas formation percentage in all regions was determined as 9% and turbidity formation percentage as 43%. Gas formation shows that the isolated lactic acid bacteria were 91% homofermentative. In the variation analyses conducted for the Afyon region; it was determined that the effect of pH change on bacterial growth was greater in the Kyrgyz kefir type. However, it was observed that bacterial diversity had a negative effect on the result in both kefir types. As a result of the variation analysis conducted for the Izmir region, it was observed that both bacterial diversity and pH change had a positive effect on bacterial diversity at the level of 0.01. It was determined that the pH bacterial difference was the same for both kefir types. For the Ankara region, it was observed that bacterial diversity had no effect on bacterial diversity, but pH diversity had a positive effect at the level of 0.01 for both kefir types. In the study, the most isolated lactic acid bacteria were Lactobacillus fermentum, Lactobacillus helveticus, Lactobacillus viridescens, Streptococcus thermophilus bacteria at 5.61%, and the least isolated lactic acid bacteria were Lactobacillus kefirgranum, Lactobacillus hilgardi, Leuconostoc lactis, Bifidobacterium bifidum, Lactobacillus crispatus, Lactobacillus curvatis, Lactobacillus delbrueckii subsp. bulgaricus, Lactobacillus delbrueckii subsp. bulgaricus, Lactobacillus gasseri, Lactobacillus hilgardi, Lactobacillus lactis, Lactobacillus rhamnousus, Lactobasillus crispatus, Lactococcus chungangensis, Lactococcus garvieae, Lactococcus rhamnousus, Lc. lactis subsp. lactis biovar. diacetylactis Leuconostoc mesenteroides, Leuconostoc spp., Streptococcus avium, Streptococcus kefir, Streptococcus lactis bacteria. As a result of the isolation, it was determined that the most isolated lactic acid bacteria species from Afyon region was Lactobacillus spp. with a rate of 50%, the most isolated lactic acid bacteria species for Izmir was Lactobacillus with a rate of 70%, and the most isolated lactic acid bacteria species for Ankara region was Lactobacillus spp. with a rate of 86%. The percentage differences of isolated lactic acid bacteria between regions are due to the type of kefir grain, the structure of the milk, any contamination of kefir obtained by traditional methods from the environment and industrial differences. The isolated lactic acid bacteria are supported by research and vary due to the process and working conditions.