A bacterium isolated from Burdwan (India) soil was found to accumulate L-valine in the growth medium and identified to be a strain of Bacillus subtilis. The strain is able to grow and accumulate valine in a purely synthetic medium, but supplementation of the synthetic medium with either Casamino acids or yeast extract or with both, significantly improves the yield. The entire fermentation period can be divided into a growth phase and a production phase, which can be prolonged by adjustment of pH to the neutral range. Among the different carbon and nitrogen sources tested glucose a t 8.5% and L-glutamic acid at O.SyO, respectively, were found most suitable. Cane sugar molasses tested as a substitute for glucose significantly stimulated growth but valine production was less. Different vitamins tested stimulated growth and valine yield and an inoculum level of 10% (v/v) of the medium was found to be optimal. The yield of valine under optimal conditions was found to be 4.53 g per litre of the medium. Valine has been isolated in crystalline form from the fermented broth by ion exchange resin chromatography and found to be a pure sample of the L-isomer.
Aniino acid production by microbial fermentation is a rapidly expanding branch of industrial microbiology. Surveys of amino acid producing organisms in soil and in other natural sources in different geographical areas have been made by many workers (KINOSHITA 1959, VELDKAMP et al. 1963, ASEEVA and KAPTEREVA 1967, BHAT et al. 1968, KASTURI and TAMHANE 1969). The present paper deals with the identification and certain aspects of d i n e production by a bacterium isolated in the course of a brief survey (CHATTOPADHYAY and BANERJEE 1971).
Results
Morphological, cultural, physiological, and biocheniical characters of the valine producing organism were studied following the Manual of Microbiological Methods.