Biochemical and molecular identification of lactic acid bacteria and yeasts with technological qualities from <i>ogi</i> (a cereal-based fermented food in Nigeria)

Abstract

Background This study aimed to isolate, characterize, and identify lactic acid bacteria (LAB) and yeasts with technological qualities from spontaneously fermented cereal gruels traditionally known as <i>ogi</i>. Material and methods LAB and yeasts were isolated and screened for pathogenicity tests using standard methods. LAB and yeasts were subjected to biochemical characterization with API 50 CHL and API 20C AUX, respectively. Molecular identification was conducted using 16S rRNA gene sequencing, ITS 4 & 5 for DNA amplification, polymerase chain reaction, gel electrophoresis, and Sanger sequencing. The technological qualities of the identified LAB and yeasts were assessed using established protocols. Results The API-based characterization of the nonpathogenic organisms revealed that the LAB mainly comprised <i>Lactobacillus</i> and <i>Lactococcus</i> genera, while <i>Candid</i>a, <i>Cryptococcus</i>, and <i>Trichosporon</i> were the prominent yeast genera. However, the results for molecular identification and percentage of occurrence showed that the LAB involved in the fermentation process mainly included <i>Lactobacillus</i> (70%) and <i>Lactococcus</i> (30%), while <i>Candida</i> (40%), <i>Cryptococcus</i> (35%), <i>Derbaryomyces</i> (10%), <i>Trichomonascus</i> (10%), and <i>Naganishia</i> (5%) were the main yeast genera. Additionally, <i>Trichomonascus ciferri</i> was identified as a novel organism isolated from ogi. Highest concentrations of lactic acid, hydrogen peroxide, and diacetyl were recorded in ogi containing <i>Lactobacillus delbrueckii</i> RSL11 and <i>Lactobacillus</i> sp. MLL5, with values of 30.0 ± 0.01 mg/g, 38.0 ± 0.00 g/l, and 46.0 ± 0.001 g/l, respectively. Conclusions Taken together, LAB and yeasts are important microorganisms with technological potentials for use as starter cultures in food fermentation processes for producing safe and functional foods.