Isolation and identification of antimicrobial-producing lactic acid bacteria from fermented cucumber

Abstract

Lactic acid bacteria (LAB) responsible for spontaneous fermentation of cucumber were isolated and their antimicrobial producing potentials were screened against 10 indicator strains. 65% of the isolated LAB produced antimicrobial activities against at least two indicator strains. The indicator strains used were: Escherichia coli, Bacillus licheniformis, B. cereus, Proteus species, Staphylococcus aureus, Salmonella species, Pseudomonas flourescence, P. aeruginosa, Serratia species and Pediococcus acidilactici. Of the 42 antimicrobial producing isolates characterized, 16, 12, 6 and 8 were identified as Lactobacillus plantarum, L. fermentum, L. acidophilus and Leuconostoc mesenteroides, respectively. Highest lactic acid producers DW7, DT6, DH13 and DF12 were selected for further investigations and were identified as L. plantarum. None of the selected L. plantarum isolates had antagonistic activity against S. aureus, Salmolnella species and P. acidilactici. The effect of pH and temperature on the antimicrobial activity of selected isolates showed that pH 5.5 and temperature 30°C were the optimum pH and temperature respectively. Thus, the selected L. plantarum isolates are good producers of antimicrobial compounds and could be suitable for application in food industry in preservation of vegetables so as to increase their shelf life.

Screening of antimicrobial activity of lactic acid bacteria isolated from <i>anango baca</i> slurry, a spontaneously fermented maize product used in Côte d’Ivoire

“…These bacteria have antibacterial activity against E. coli pathogen unlike our strains. But our findings are similar to those of Wakil and Osamwonyi (2012) who also isolated and identified LAB of the fermenting millet gruel from Nigeria as being L. plantarum, L. fermentum, L. meseteriodies, L. jensenii, L. brevis, P. acidilactici and Lactobacillus spp. with the predominance of L. plantarum.…”

“…Similarly, for akamu, a Nigerian fermented maize food, the pH ranges from 3.22 to 3.95 (Obinna-Echem et al, 2013). In anango baca, LAB are responsible for primarily producing lactic acid, which is a common characteristic of the fermentation of cereal foods (Adebayo and Aderiye, 2007;Omemu, 2011;Wakil and Osamwonyi, 2012). The produced acids play a major role in the reduction of the pH in the medium, thereby making it acidic.…”

“…The produced acids play a major role in the reduction of the pH in the medium, thereby making it acidic. The acidic medium is therefore responsible for the inhibitory effects against pathogens and spoilage bacteria as well as for the improved microbiological stability and safety of the food product (Wakil and Osamwonyi, 2012).…”

“…Many authors have used agar spot method to demonstrate antimicrobial activity of LAB against one or more of indicator spoilage or food borne pathogens (Lei and Jacobsen, 2004;Kivanç et al, 2011;Okpara et al, 2014). The fact that the 47 isolates also exhibited some inhibitory activity against indicator strains when the pH of the medium was not neutralized, might be due to the presence and activity of various antimicrobial compounds such as organic acids by decreased pH levels (Wakil and Osamwonyi, 2012;Gaamouche et al, 2014). Inhibition of the growth of indicator strains by organic acids production is a common phenomenon observed during lactic acid fermentation.…”

Evaluation of the Allergenic Potential of Anagobaka infant Flours Marketed in the Markets of the District of Abidjan

“…The pH variation of a food favor or inhibit the growth of microorganisms in this food [22]. The acidic medium is responsible for inhibiting the growth of pathogenic microorganisms [23]. This explains the absence of bacterial microorganisms in our samples whose pH values were slightly acidic.…”