The Antibacterial Activity of Lactic Acid Bacteria from Pickled Spondias dulcis (Ambarella) against Foodborne Pathogens

Pickled fruits are popular condiment not only in Malaysia but in many other countries as well. During the natural pickling process, the lactic acid bacteria are known to be able to produce several antibacterial compounds. The pickled Spondias dulcis or ambarella is among commonly consumed pickled fruit in Malaysia and may be a promising source of lactic acid bacteria. Application of lactic acid bacteria as an alternative to chemical food preservative is believed as natural, safer and sustainable. This study was carried out to isolate and identify lactic acid bacteria from Malaysian local pickled Spondias dulcis and to determine their antibacterial activity against selected Gram-positive and Gram-negative foodborne pathogens. The isolation of lactic acid bacteria was done using a standard method and the isolated colonies with positive preliminary identification based on their morphology on agar, Gram-positive staining characteristic and their negative catalase reaction were chosen for identification with polymerase chain reaction amplification of 16S rRNA gene and sequencing. A total of 2 lactic acid bacteria have been successfully isolated and identified as Lactobacillus fermentum (LABS1) and Enterococcus durans (LABS2). Both isolates were able to demonstrate antibacterial activity against foodborne bacterial pathogens used in this study. This result suggested that the isolated lactic acid bacteria from pickled S. dulcis may have a potential to be applied as natural preservative to control the growth and fight against certain pathogens in food. HIGHLIGHTS Pickled Spondias dulcis is a promising source of lactic acid bacteria having antibacterial activity against foodborne bacterial pathogens Two isolates of LAB identified as Lactobacillus fermentum (LABS1) and Enterococcus durans (LABS2) from pickled Spondias dulcis (ambarella) possessed antibacterial activity against a total of 10 Gram-positive and Gram-negative foodborne pathogens The antibacterial activity using cell free supernatant (CFS) of both LABS1 and LABS2 suggested that they may have potential as natural preservative GRAPHICAL ABSTRACT