Biodiversity analysis of lactic acid bacteria (LAB) in naturally fermented garcinia mangostana (GM) pericarp / Nur Arif Ibrahim

This study aims to isolate bacterial species and to enumerate the Lactic acid bacteria (LAB) species of Garcinia Mangostana (GM) pericarp cider at different fermentation stages as well as to establish bacterial growth profile during fermentation of GM pericarp. Throughout the fermentation process, cell mass concentration is determined by using cell dry weight method. The highest cell dry mass obtained was 0.008 g at day 29 meanwhile the lowest was 0.001 g at day 88. Due to secretion of Lactic acid by LAB, the pH of the fermentation broth decreasing and overall pH range recorded at 3.46 to 4.00. Since the main concern of this paper is biopreservation and food safety of the GM cider, at this range of pH common foodborne pathogen unable to growth and survive. It was detected that LAB is a predominant species of microorganism present in the cider (2.85 – 6.04 log CFU/ml). The Gram stain done on the samples show the bacteria present starting at the beginning until the end the fermentation has a purple, violet stain when observed under microscope. Most of the sample appeared Staphylococcus, Staphylobacilli, Streptococcus and Streptobacilli. Based on this gram stain, LAB is the dominant bacteria that present during the fermentation period. During fermentation carried out, there were three phases where different strain of LAB dominated the cider.