Screening of Indonesian marine bacteria and their potential for D-tagatose production

Abstract

A rare natural ketohexose, D-tagatose, has attracted an increasing interest as sucrose substitute due to its low caloric value and similar properties to sucrose. D-Tagatose is enzymatically produced by using L-aldose isomerase (LAI) as catalyst and D-galactose as substrate. Therefore, a continuous effort to obtain a new isolate with high LAI activity is needed. Therefore, our collection of marine bacteria was assayed by employing designed minimum culture media with 0.5% (w/v) D-galactose as the sole carbon source. D-Tagatose production ability of bacterial strains were investigated and quantified by high performance liquid chromatography (HPLC). Our investigation showed that from 23 Indonesian marine bacteria, a total 18 bacteria possessed the ability to grow in the designed media. This result was subsequently confirmed using HPLC and showed that a total of four isolates, namely isolates LBF 110, 138, 108, and 131, exhibited a D-tagatose yield. Isolates LBF 110 and 138 were identified in this study according to molecular identification 16S rRNA method as Bacillus xiamenensis, and Brevibacterium sediminis, respectively. The other two isolates, LBF 108 and 131, were already identified in previous study as Shewanella algae and Pseudomonas stutzeri, respectively. This result suggests the potential of these isolates as D-tagatose producing bacteria.