Microbacterium lacticum; a Lysine Producing Bacterium Isolated from Oil-contaminated Soil in South-East Nigeria

Aims: To screen for lysine production using hydrocarbon utilizing bacteria isolated from oil-contaminated soil.
Study Design: Study of the isolation and fermentation process in shake flask culture.
Place and Duration of Study: Department of Applied Microbiology and Brewing, Nnamdi Azikiwe University. Awka, Nigeria between 2009 to 2010.
Methodology: Collection of Samples: Enrichment of hydrocarbon- degrading bacteria was done in the basal medium. The carbon source consisted of 0.5 ml of the hydrocarbons added to a sterile filter paper secured in the lids of the Petri dishes. The isolates were screened for lysine production.
Results: Sixteen of the one hundred and forty isolates were found to produce lysine on solid agar medium. The strains were tested for lysine production in their broth after 3 days at 30°C. Among the different hydrocarbons tested groundnut oil and motor oil were found to be suitable. Active strain designated G1, which produced the highest lysine yield of 1.44 mg/ml under submerged condition was characterized. The gram-positive, irregular, slender rod, utilizing citrate, urease, tyrosine and reduces nitrate was identified as Microbacterium lacticum.
Conclusion: We have isolated many strains of hydrocarbon utilizing microorganisms, in order to examine if the reasonable amounts of lysine of economic value can be produced by those microorganisms from hydrocarbons such as kerosene, gasoline, motor oil, spent oil, crude oil, which are considered to be more economical and readily available carbon sources than carbohydrates. Lysine producing bacteria can be isolated from Nigeria soil and improving cultural conditions of hydrocarbon utilizers in submerged medium accumulated lysine.