Antibacterial Metabolites obtained from fermentation of peanut and cowpea by <i>Lactobacillus</i> spp

Abstract

Lactic acid bacteria elective habitat is food matrix, where they release encrypted metabolites from several parent proteins as a result of their proteolytic activity in the matrix. These metabolites when decrypted confer different bioactive activity thus improving public health. This study was aimed at producing peptide containing metabolites with antibacterial efficacy from defatted cowpea and peanut using Lactobacillus spp. Lactobacillus spp. isolated from spoilt yoghurt were identified using culture dependent and independent method. The isolates were screened for proteolytic ability on skimmed milk agar. The selected isolate with highest proteolytic activity was used for metabolites production through fermentation of defatted cowpea and peanut at 37 ^oC for 72 h. Parameters analyzed during fermentation were pH, Lactobacillus count, protease activity, peptide concentration and antibacterial activity. The crude peptides produced were assayed for antibacterial activity against bacteria isolated from spoilt meat. From the identified Lactobacillus spp., L. plantarum CAU4347 had the highest proteolytic activity with clear zone of 24.50 ± 0.707 mm. During fermentation the highest and lowest Lactobacillus counts were from cowpea and peanut media with values 294.2 ± 0.21 ×10⁷ and 0.60 ± 0.4 ×10⁷ cfu/ml respectively. Cowpea medium inoculated with L. plantarum CAU4347, had the highest peptide concentration of 79.92 ± 0.01 µg/ml. Consequently, peanut medium showed higher antibacterial activity of 18 mm against Escherichia coli. This result finding suggests that encrypted peptide metabolites from cowpea and peanut flour can confer antibacterial activity against meat spoilage bacteria thus could be utilized as a potential bio-preservative.

Keywords: Metabolites, Cowpea, Peanut, Bioactive, Fermentation, Lactobacillus plantarum