Fermentation and recovery of L-glutamic acid from cassava starch hydrolysate by ion-exchange resin column

Abstract

Investigations were carried out with the aim of producing L-glutamic acid from Brevibacterium sp. by utilizing a locally available starchy substrate, cassava (Manihot esculenta Crantz). Initial studies were carried out in shake flasks, which showed that even though the yield was high with 85-90 DE (Dextrose Equivalent value), the maximum conversion yield (~34%) was obtained by using only partially digested starch hydrolysate, i.e. 45-50 DE. Fermentations were carried out in batch mode in a 5 L fermenter, using suitably diluted cassava starch hydrolysate, using a 85-90 DE value hydrolysate. Media supplemented with nutrients resulted in an accumulation of 21 g/L glutamic acid with a fairly high (66.3%) conversation yield of glucose to glutamic acid (based on glucose consumed and on 81.74% theoretical conversion rate). The bioreactor conditions most conducive for maximum production were pH 7.5, temperature 30°C and an agitation of 180 rpm. When fermentation was conducted in fed-batch mode by keeping the residual reducing sugar concentration at 5% w/v, 25.0 g/L of glutamate was obtained after 40 h fermentation (16% more the batch mode). Chromatographic separation by ion-exchange resin was used for the recovery and purification of glutamic acid. It was further crystallized and separated by making use of its low solubility at the isoelectric point (pH 3.2).

Optimization of Corynebacterium glutamicum Glutamic Acid Production by Response Surface Methodology

“…The current production of glutamate is more than 1.5 million tons per year worldwide (Shimizu and Hirasawa 2006). Production of glutamate using various substrates, microorganisms, and nutrient solutions has been reported (Das et al 1995;Nampoothiri and Pandey 1996;Nampoothiri and Pandey 1999;Jyothi et al 2005). Owing to the importance of the particular industrial fermentation, much effort is still going on to improve the GA fermentation process especially from the standpoint of saving in production cost.…”

“…In previous studies with regard to GA production from agricultural waste, the conventional "change-one-factor-ata-time" method has always been used for multifactor experiment design (Das et al 1995;Nampoothiri and Pandey 1999;Jyothi et al 2005). The single-dimensional research is laborious, time-consuming, and incapable of reaching the true optimum due to ignoring the interaction among variables.…”

Studies on Lysine Accumulation in the Broth Culture of Bacillus Species using Carbohydrates as Carbon Sources and Seed Meals as Nitrogen Sources

“…Other workers used different starch hydrolysate for amino acid production. Nampoothiri and Pandey, (1999) reported that strain of Brevibacterium sp DSM utilized cassava starch hydrolysate and accumulated 21g/l of L-glutamic acid. Kubota et al (1970), used sweet potato starch hydrolysate and obtained 5.20g/l of L-lysine HCl by threonine-valine auxotroph of Brevibacterium lactofermentum.…”

Sugar- and Starch-Based Biorefineries

“…in the year 2007 and has risen by 2010 to over 2 Mio mto. 72 Pure sugars are usually favorable compared with molasses because of unwanted side reactions and changing qualities of the complex media components. MSG functions as umami flavor enhancer in food.…”