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Abstract
Methionine is an essential amino acid required in the diet of humans and mammals. Presently methionine is being produced by chemical and enzymatic methods. Chemical methods require hazardous chemicals and enzymatic method requires expensive enzymes. After the discovery of glutamic acid producing bacteria by Kinoshita et al. a number of microorganisms capable of producing amino acids have been separated and attempts have been made to over produce L-methionine by fermentation. But none of the methionine production process has become commercialized so far. In the present work, the effect of fermentation parameters such as temperature, pH, volume ratio of medium/fermenter, inoculum size and agitation (rpm) and nutritional parameters such as carbon source, nitrogen source and calcium carbonate on growth and methionine production by C.glutamicum using agricultural products were examined. After 96 hours of fermentation, Maximum biomass and methionine accumulation were 4.16 g/l and 4.6 g/l respectively with temperature 300C, pH 7.0, volume ratio of medium to fermenter 30 ml/ml, inoculums size 3 ml, agitation 170 rpm, plantain starch hydrolysate as carbon source 20 g/l, groundnut as nitrogen source 10 g/l and CaCO3 20 g/l.
Key words: L-Methionine, C.glutamicum, Optimization and Production
INTRODUCTION
Methionine is an essential sulfur containing amino acid that is required in the diet of humans and mammals for normal growth and function of body metabolism. Sulfur containing amino acids first had been detected in 1847 at Liebig's laboratory by Fleitmann [1], where he discovered heat instability of proteins in strong alkali solutions. Later, Osborne [2] determined in highly purified proteins two sulfur containing amino acids and one of them as correctly attributed to cysteine and the other was first isolated from casein and described later by Muller [3]. Three years later, Barger and Coyne [4] identified chemical formula as methylthiol-a-aminobutyric acid and suggested and agreeing with Dr. Mueller, the shorter name as methionine. Dietary deficiency of methionine leads to diseases such as toxemia, childhood rheumatic fever, muscle paralysis, hair loss, depression, schizophrenia, Parkinson's disease, liver deterioration, and impaired growth [5]. In humans, some genetic diseases like cystathioninuria and homocystinuria are caused by defective metabolism of methionine [6]. Patients suffering from these diseases may exhibit one or more symptoms such as mental retardation, seizures, thrombocytopenia, clubfoot, skeletal abnormalities, lens dislocation, and...