Technological properties and genetic profile of lactic acid bacteria isolated from Cameroonian tropical fruits

Abstract

This investigation aimed to evaluate the acidifying, proteolytic, lipolytic and texturizing activities of lactic acid bacteria (LAB) isolated from tropical fruits (pineapple, papaya, orange and banana) collected at Foreke (City of Dschang, Menoua Division, West Cameroon region).Firstly, LAB was isolated and characterized at the generic and technological levels.Secondly, the genetic diversity of LAB isolates was highlighted using Random Amplified Polymorphic DNA (RAPD).As a result, twenty six LAB isolates were facultative heterofermentative and presumptly belonging to the genus Lactobacillus.Only 4 of them (N1B6, N2P4, N3A3, N1O5) showed an acidifying activity higher than 35°D after 6 h of incubation and were considered as isolates of interest.In addition, the highest acidifying activities (47.540 ± 0.505°D, 88.857 ± 0.248 °D, 93.433 ± 0.513 °D) after different incubation times (6, 12 and 24 h) were recorded by N1O5 isolate.All the selected LABs isolates showed growth with proteolysis and the diameter of lysis zones varied from 4.25 ± 0.35 mm (N1B6) to 7.80 ± 0.28 mm (N3A3).Also, lipolytic activity was detected in all LAB with the highest activity (10.05±0.07)highlighted by isolate N1B6.Except for isolate N1O5, all the other isolates produced exopolysaccharides.RAPD showed that isolates N3A3, N1B6 and N2P4 are genetically close and different from isolate N1O5.In addition, all these LAB isolates were different from certain reference LAB strains (Lactiplantibacillus plantarum H21, Lacticaseibacillus paracasei 62L, Lactiplantibacillus paraplantarum 78L, Levilactobacillus brevis 77L) based on RAPD.Thus, given the properties of commercial interest, these isolates can be used to ferment dairy products.