Abstract
Dairy food staff such as soft cheese,cream cheese,raw milk,sour cream,yoghurt and probiotic yoghurt products can be a rich source of diverse lactic acid bacteria.The objective of this lab practical was to isolate lactic acid bacteria(LAB) form raw milk,establishment of pure cultures of LAB,identify LAB and phage recovery and enumeration of recoverd phage.Raw milk was chosen as a sample so as to have a more positive result.To identify bacteria Lab isolated from raw milk,biochemical,morphological ,physiological and cultural characteristics were employed. The purification of isolates was done by moving Gram +ve ro ds and cocci shaped bacteria to selective media MRS and M-17 plates. The isolates were sub cultured till pure …show more content…

For determination of citrate utilization and acetone production, citrate and MR-VP agars were used. MRS or M17 broths with Durham tubes were used for determination of gas production and the detrin production from sucrose was done in MSR.To assess the sugars fermentation in a medium a solution with the following composition was used (gL-1): bovine extract, 10.0; neopepton, 10.0; yeast extract, 5.0; K2HPO4, 2.0; CH3COONa+3H2O, 5.0; diamonium citrate, 2.0; MgSO4, 0.2; MnSO4, 0.05; brom-cresol-purple, 0.17; tween 80, 1 mL. Carbon utilization was also tested.

Phage induction
MRSA broth liquid culutures were equally divided into two sterile tubes.Each tube was labeled as ‘mitomycin C’ and the other as ‘control’. 500µl of micomycin was added to the tube labelld as ‘mitomycin’ and ascpetic techniques of flaming the neck before and after adding the mycomycin.
A starch agar plate marked STA containing nutrient agr with soluble starch was already provided.A casein agar plate that contained nutrient agar mixture added skim milk was given and marked CA.
All the three plates were inoculated by streaking of the MRSA Lactobacillus lattis culture. This was done with the help of the loop. The loop was flamed and a colony of the culture was collected. The plates were then streaked with the culture. The plates were then incubated for 12-18 hours at 37oC. The bacteria were also transferred into the nutrient agar plate to set up for