Co-production of functional exopolysaccharides and lactic acid by Lactobacillus kefiranofaciens originated from fermented milk, kefir

Abstract

Kefiran is a functional exopolysaccharide produced by originated from kefir, traditional fermented milk in the Caucasian Mountains, Russia. Kefiran is attractive as thickeners, stabilizers, emulsifiers, gelling agents and also has antimicrobial and antitumor activity. However, the production costs of kefiran are still high mainly due to high cost of carbon and nitrogen sources. This study aimed to produce kefiran and its co-product, lactic acid, from low-cost industrial byproducts. Among the sources tested, whey lactose (at 2% sugar concentration) and spent yeast cells hydrolysate (at 6 g-nitrogen/L) gave the highest kefiran of 480 ± 21 mg/L along with lactic acid of 20.1 ± 0.2 g/L. The combination of these two sources and initial pH were optimized through Response Surface Methodology. With the optimized medium, produced more kefiran and lactic acid up to 635 ± 7 mg/L and 32.9 ± 0.7 g/L, respectively. When the pH was controlled to alleviate the inhibition from acidic pH, could consume all sugars and produced kefiran and lactic acid up to 1693 ± 29 mg/L and 87.49 ± 0.23 g/L, respectively. Moreover, the fed-batch fermentation with intermittent adding of whey lactose improved kefiran and lactic acid productions up to 2514 ± 93 mg/L and 135 ± 1.75 g/L, respectively. These results indicate the promising approach to economically produce kefiran and lactic acid from low-cost nutrient sources.

Kefir micro-organisms: their role in grain assembly and health properties of fermented milk

“…), being only the first subspecies considered responsible for kefiran production (Cheirsilp et al . ).…”

“…kefiranofaciens and ssp. kefirgranum (Vancanneyt et al 2004), being only the first subspecies considered responsible for kefiran production (Cheirsilp et al 2018).…”

Peculiarities of microbial exopolysaccharide ethapolan synthesis on mixed waste oils

“…Under such conditions, the producer synthesized 9.9 g/l of polysaccharide, which in 2.2 times more than under one-time adding of the substrate [15]. The fractional adding of milk whey into the cultivation medium of Lactobacillus kefiranofaciens JCM 6985, producer of EPS kefiran, was accompanied by increase of the synthesized polysaccharide concentration almost in 2 times (to 2514 ± 93 mg/l), compared to the one-time substrate addition [16]. Concentration of EPS, synthesized by marine bacteria Zunongwangia profunda SM-A87 on milk whey with a fractional adding of this substrate into 5 L fermenter reached 17.2 g/l [17].…”

Statistical optimisation of the exopolysaccharide production by Lactobacillus fermentum Lf2 and analysis of its chemical composition

“…Constant pH values during fermentation may inhibit the enzymatic hydrolysis of these molecules since the action of hydrolases is favoured below pH 5 (Degeest et al ). Several reports have indicated better results with pH control than with free‐pH fermentations (Ale et al ; Cheirsilp et al ).…”