Isolation and Identification of a mutant strain of brevibacterium linens to improve L-Iysine production.

Twelve Coryneform bacterial isolates were isolated from local cheese samples using selective enrichment technique and identified in accordance to the cultural, morphological and biochemical tests. Most isolates found to be belonged to Brevibacterium and isolate TI was presumably identified as Brevibacterium linens. Two isolates (T5 and T9) were found to be glutamic acid producers as indicated by the, different chromatographic tests (paper, thin layer and high performance liquid chromatography).2. Isolate T2 was selected for mutation programme with MNNG to obtain auxotrophic mutants. A concentration of 250
ug MNNG /ml for 30 minutes was used for inducing mutation. Twenty-three mutants were selected as auxotrophes which have been subjected to a second round of mutation in order to isolate desired single or double auxotrophes.3. Mutant
isolate TM2-22 was obtained as methionine -threonine double auxotrophic mutant and
capable of lysine.4. production after testing by different chromatographic techniques and selective colorometric method with ninhydrin reaction. 4.Production parameters including temperature and pH for lysine production by mutant isolate TM2-22 was studied. Maximum production was found to be at incubation temperature of 30°C and pH(7). However, a decrease in pH was found during cultivation period has used as an indicator for amino acid production. 5. Nutritional requirements for growth and production of lysine was also studied. Glucose (4%) found to be the best carbon source, and ammonium sulphate (5%) was found to be the best nitrogen source.