Molecular Diversity And Technological Properties Of Predominant Microorganisms Associated With The Processing Of Millet Into Fura, A Fermented Food In Ghana

ABSTRACT Fura is a millet-based spontaneously fermented dumpling produced and consumed in parts of West Africa, particularly Nigeria, Burkina Faso and Ghana. From eight (8) traditional fura production sites in northern Ghana, lactic acid bacteria (LAB) and yeasts were isolated, characterized and identified using genotypic methods. These included (GTG)5-based rep-PCR fingerprinting, sequencing of the 16S rRNA gene, multiplex PCR by means of recA gene sequence comparison and sequencing of D1/D2 region of 26S rRNA genes. Following identification, the predominant LAB were assessed for some technological properties including rates of acidification, exopolysaccharide production, amylase production and bacteriocin activities. The identified yeasts were also assessed for their probiotic potential by measuring tolerance to low pH (2.5), bile salt (0.3% oxgall) and temperature (37°C). Based on the genotypes, the LAB species associated with fura processing include L. fermentum (40.8%), W. confusa (19.0%), L. reuteri (13.9%), P. acidilactici (11.8%), L. salivarius (8.1%) and L. paraplantarum (6.3%). L. fermentum predominated in all fermentations (p< 0.05) and uniformity was observed among production sites regarding the dominance of L. fermentum. L. fermentum and W. confusa were isolated in all production sites and almost at all fermentation stages indicating that they are indigenous to traditional fura processing. The yeast species identified include Candida krusei (60%), Kluyveromyces marxianus (38%), Candida tropicalis (0.6%), Candida rugosa (0.2%), Candida fabianii (0.4%), Candida norvegensis (0.6%) and Trichosporon asahii (0.4%). C. krusei and K. marxianus were found to be the dominant species throughout the fermentation and were isolated from all production sites. Generally, majority of predominant LAB strains showed faster acidification rates, high exopolysaccharides production and the ability to inhibit pathogens through the production of bacteriocins. Yeasts isolated from fura survived and grew at human gastrointestinal conditions of pH 2.5 and 0.3% (w/v) oxgall at 37°C over 4 h duration. Additionally, strains of C. krusei, K. marxianus, C. rugosa and T. asahii were able to increase the relative TEER of Caco-2 monolayers after 48 h,  making them possible candidates for the development of starter/co-cultures with probiotic potentials. The study has shown the diversity of microorganisms associated with fura processing. It has also revealed the technological properties of the microorganisms that impact on the product and therefore provided the basis for development of starter cultures.