Evaluation of production and kinetics parameters of rare sugar (D-tagatose) using biocatalyst Arthrobacter globiformis

Abstract

Purpose – Dulcitol (Galactitol) is a sugar alcohol which is produced by redox reaction of galactose. It has been reported that the D-tagatose can be produced from dulcitol (D-galactitol) via the oxidation reaction by the acetic acid bacteria such as Arthobacter globiformis, Gluconobacter oxydans. The D-tagatose sugar is a ketohexose monosaccharide sweetener, which is an isomer of D-galactose. D-tagatose is rarely found in nature and it can be utilized in many ways particular in prebiotic property. The purpose of this paper is to speak about the production and kinetics of D-tagatose from dulcitol using a wild strain of Arthobacter globiformis MTCC 944. Design/methodology/approach – The wild strain Arthobacter globiformis was procured from Microbial Type Culture Collection, Chandigarh and was grown in slants (Dulcitol of 2 percent (w/v)) by sub culturing for every two weeks until transferred to production medium containing 10 percent (w/v) of dulcitol operating aerobically at 25°C and 180 rpm. Biomass estimation was carried out taking samples periodically and measuring its OD value using spectronic-20D spectrophotometer at 600 nm. Kinetics of biomass was determined using Logistic growth kinetic model and that of D-tagatose production was estimated using Leudking-Piret model. Findings – The maximum production of D-tagatose (3.82 g/L) was obtained at the initial dulcitol concentration of 20 g/L and at a pH of 6.0 and temperature of 25°C. Effect of inoculum size on the fermentation of D-tagatose was studied. Threefold increases in yield of tagatose was achieved at the higher inoculum concentration of 24 percent v/v. Originality/value – The strain Arthrobacter globiformis, selected for the production of D-tagatose is not much investigated strain. Dulcitol, the substrate chosen for the study is less expensive when compare with galactose which is largely used by the investigators.