Investigation of the diversity and safety of the predominant Bacillus pumilus sensu lato and other Bacillus species involved in the alkaline fermentation of cassava leaves for the production of Ntoba Mbodi

Abstract

The objective of the study was to investigate the identity, diversity, and safety of the Bacillus population involved in the fermentation of cassava (Manihot esculenta Crantz) leaves for the production of Ntoba Mbodi, a Congolese food. Ninety bacteria were identified by phenotyping and genotyping using ITS-PCR, rep-PCR, and sequencing of the 16S rRNA, gyrA, gyrB and rpoB genes. Moreover, the isolates were screened for the presence of genes coding for haemolytic (HblC, HblD) and non-haemolytic enterotoxins (NheA, NheB and NheC), cytotoxin K (CytK) and emetic toxin (EM1) as well as their ability to produce haemolysin.The investigations revealed the predominance (72.2%) of species of the Bacillus pumilus group i.e. B. safensis (48), B. pumilus (7), and B. pumilus sensu lato (10). Other species of Bacillus including B. cereus sensu lato (11), B. megaterium (4), B. subtilis (4), B. amyloliquefaciens (2), B. siamensis (2), B. licheniformis (1) and Lysinibacillus louembei (1) were also identified. Haemolytic, non-haemolytic and cytokin toxin genes were detected in the B. cereus strains which were also able to produce haemolysin. The emetic toxin gene was not detected in any isolates. The toxin genes screened were not detected in any of the non B. cereus species.