Decolorization of molasses melanoidins and palm oil mill effluent phenolic compounds by fermentative lactic acid bacteria.

Lactobacillus plantarum SF5.6 is one of the lactic acid bacteria (LAB) that has the highest ability of molasses melanoidin (MM) decolorization among the 2114 strains of LAB. The strains were isolated from spoilage, pickle fruit and vegetable, soil and sludge from the wastewater treatment system by using technical step of enrichment, primary screening and secondary screening. This LAB strain SF5.6 was identified by 16S rDNA analysis and carbohydrate fermentation (API 50 CH). The top five LAB strains having high MM decolorization (> 55%), namely TBSF5.8-1, TBSF2.1-1, TBSF2.1, FF4A and SF5.6 were selected to determine the optimal condition. It was found that the temperature at 30 degrees C under facultative conditions in GPY-MM medium (0.5% glucose, 0.1% peptone, 0.1% yeast extract, 0.1% sodium acetate, 0.05% MgSO4 and 0.005% MnCl2 in MM solution at pH 6) giving a high microbial growth and MM decolorization for all five strains. It was noticed that the decolorization of MM by LAB strains might be cell growth associated. L. plantarum SF5.6 grew rapidly within one day while the other strains took 2-3 days. This L. plantarum SF5.6 could rapidly decolorize MM to 60.91% without any lag phase, and it also had the ability to remove 34.00% phenolic compounds and 15.88% color from treated palm oil mill effluent.