Diversity and functionality of bacillus species associated with alkaline fermentation of bambara groundnut (Vigna subterranean L. Verdc) into dawadawa-type African condiment

Abstract

The aim of this study was to investigate the diversity of Bacillus species in dawadawa; aiding potential starter cultures selection for alkaline fermentation of bambara groundnut into dawadawa-type condiments based on their genotypic and volatile compound profiles. Bacillus species (n = 71) isolated from spontaneously fermented dawadawa were identified using matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) as B. cereus (35%), B. licheniformis (30%), B. pumilus (21%), B. subtilis (10%) and B. amyloliquefaciens (4%). Further molecular typing was performed using GTG 5 rep-PCR typing, 16S rRNA and gyrA gene sequencing. The gyrA gene sequence analysis exhibited the highest species discriminatory power with B. subtilis subsp. subtilis, B. amyloliquefaciens subsp. plantarum, B. pumilus and B. licheniformis as the distinct clusters. Representative strains from each cluster were then used as starter cultures for the production of dawadawa from bambara groundnut. Volatile compounds analysis using headspace solid phase microextraction (SPME) and comprehensive gas chromatography coupled to time of flight mass spectrometry (GC × GC-TOF MS) identified distinct chemical profiles produced by each of the four strains. Volatile compounds produced by B. subtilis subsp. subtilis (strain SFBA3) were categorized by dimethyl disulfide, methanethiol and nonanal while B. amyloliquefaciens subsp. plantarum (strain SFBA2) produced acetic acid and hexadecanoic acid. B. cereus (strain PALB7) produced 2,5-dimethyl pyrazine and 2-butanone which were not detected in the other condiments. Hexanal was the main compound produced by B. licheniformis (strain OALB7).

Metabolite profile of Bambara groundnut (Vigna subterranea) and dawadawa (an African fermented condiment) investigation using gas chromatography high resolution time-of-flight mass spectrometry (GC-HRTOF-MS)

“…Compounds belonging to the sulphur related group were mostly present in the DD with none detected in the BGN, in agreement with the study of Akanni et al. (2018b) , in which sulphur-related compounds were equally not detected in the raw BGN.…”

Volatile compounds produced by Bacillus species alkaline fermentation of bambara groundnut (Vigna subterranean (L.) Verdc) into a dawadawa-type African food condiment using headspace solid-phase microextraction and GC × GC–TOFMS

“…subtilis SFBA3, Bacillus amyloliquefaciens subsp. plantarum SFBA2, Bacillus cereus PALB7, and Bacillus licheniformis OALB2 isolated and characterized from previous work in our research group [20] were used to inoculate bambara groundnuts sourced from Zimbabwe, Southern Africa, by Triotrade (Silverton, South Africa).…”

Consumer acceptability, metabolite profile analysis and storage stability of sorghum‐Bambara groundnut mahewu

“…Several reports have identified similar volatile compounds found in fermented sorghum. Likewise, these volatile compounds have also been reported in fermented BGN but their concentrations vary (Akanni et al ., 2018a, 2018b; Kewuyemi et al ., 2020). Although legumes have widely been used to improve the nutritional quality of sorghum‐based foods, several research have investigated the effect of such supplementation on the metabolites profile.…”