Production and characterization of microbial levan using sugarcane (Saccharum spp.) juice and chicken feather peptone as a low-cost alternate medium

Abstract

An alternate medium consisting of sugarcane juice (SJ) (Saccharum spp.) and chicken feather peptone (CFP) was employed for microbial synthesis of levan. SJ has considerable amounts of vital minerals, vitamins, and amino acids in addition to its major constituent, sucrose. Meanwhile, CFP is also a rich source of essential nutrients such as amino acids, micro and macro elements. Amino acids present in SJ and CFP, such as glutamic acid, arginine, aspartic acid, asparagine and elements such as Ca, Mg favoured the cell growth and levan production. In this present work, levan was produced using Bacillus subtilis MTCC 441 in five different media, namely, sucrose along with defined nutrients (M1), Sugarcane Juice without nutrients (M2), SJ with defined nutrients (M3), SJ along with chicken feather peptone (M4) and sucrose without nutrient (M5). Alternative nutrient medium using SJ and CFP (M4) showed a promising levan yield of 0.32 ± 0.01 g of levan/g of sucrose consumed, which is 64% of the theoretical levan yield possible. Levan produced was characterized using Nuclear Magnetic Resonance (NMR) and Gel Permeation Chromatography (GPC). There is a change in low molecular weight fractions of levan obtained from SJ and CFP medium compared to the defined medium. Produced levan from the composite medium exhibited strong antioxidant activity and was biocompatible when tested against endothelial cells. The substrate cost was 20% lower than the cost of defined medium. Thus, a composite medium made of SJ and CFP can serve as an alternate low-cost medium for microbial fermentation.