Characteristics of a red-pigmented thermotolerant bacteria (GSB-001) isolated from Gedong Songo hot spring, Bandungan, Semarang – Indonesia

Abstract

Aims: Pigments used as food additives for a long time and people prefer natural pigment than synthetic ones because of their safety. Microorganisms are interesting for pigment production and many of them have been used in food industry. Many research have been conducted to find out for natural pigment sources. The objective of this research was to investigate the characteristics of a red-pigmented bacteria isolated from Gedong Songo hot spring, Bandungan-Indonesia. Methodology and results: Bacterial isolates were grown on Nutrient Agar for 24 h, and the morphology of the colonies and of the cells were identified. Biochemical tests included indole, methyl red, catalase, urease tests and carbohydrate fermentation. Molecular identification was based on 16S rRNA sequence. The isolate was a rod shape and Gramnegative. Biochemical tests showed that the isolate was indole negative, catalase positive, methyl red negative and urease negative. This isolate was glucose, maltose and sucrose positive and negative for lactose. 16S rRNA sequence was BLAST and it matched with Serratia marcescens strain S823. The red pigment antioxidant activity showed the highest DPPH radical scavenging of 49.11% obtained from 48 h of incubation. Functional group of S. marcescens pigment on Fourier Transform InfraRed Spectroscopy (FTIR) displayed specific peak at 1740 cm-1 represented of C═O (carbonyl) stretching group. Conclusion, significant and impact of study: Based on morphological, biochemical and moleculer identifications, it showed that the bacteria isolated from Gedong Songo hot spring Bandungan-Indonesia had 94% homology with Serratia marcescens strain S823. Based on DPPH radical scavenging test, it demonstrated that S. marcescens had potency as an antioxidant.