Sourdough is one of the oldest technologies employed by humans to leaven bread because of its ability to enhance the flavour and structure of bread using micro-organisms. However, there is a lack of comprehensive information in Botswana regarding the diversity of sourdough starters and the fermentative micro-organisms responsible for spontaneous fermentation. The present study aimed to explore the microbial species diversity of sourdoughs in Botswana and gain insight into the unique microbial communities involved in sourdough production. A total of nine samples were collected from different areas in Botswana. The microbial diversity in sourdoughs was characterized through the sequencing of amplicons of the 16S ribosomal DNA and internal transcribed spacer regions. In silico polymerase chain reaction–restriction fragment length polymorphism and phylogenetics were utilized to determine the genetic diversity among the isolates. The dominant yeast species identified were Saccharomyces cerevisiae, Wickerhamomyces anomamlus, Pichia kudriazverii and kazachstania humilis. Additionally, the presence of Lactiplantibacillus plantarum, Lacticaseibacillus paracasei, Liquorilactobacillus nageli and Bacillus cereus was also detected. It is worth noting that two species of acetic acid bacteria (AAB), namely Acetobacter pasteurianus and A. indonesiensis, were isolated, though in low levels, but the finding is significant in sourdough fermentation. The low occurrence of AAB (acetic acid bacteria) species observed in this study could be an important finding, as these bacteria are considered understudied, yet they are known to contribute significantly to the final product.

Opportunistic infections due to Cryptococcus neoformans and C. gattii species complexes continue to rise unabated among HIV/AIDS patients, despite improved antifungal therapies. Here, we collected a total of 20 environmental and 25 presumptive clinical cryptococcal isolates from cerebrospinal fluid (CSF) samples of 175 patients enrolled in an ongoing clinical trial Ambition 1 Project (Botswana-Harvard Partnership). Identity confirmation of the isolates was done using MALDI-TOF MS and PCR. We describe the diversity of the isolates by PCR fingerprinting and sequencing (Oxford Nanopore Technology) of the intergenic spacer region. Mating types of the isolates were determined by amplification of the MAT locus. We report an unusual prevalence of 42.1% of C. neoformans x C. deneoformans hybrids Serotype AD (n = 16), followed by 39.5% of C. neoformans Serotype A (n = 15), 5.3% of C. deneoformans, Serotype D (n = 2), 7.9% of C. gattii (n = 3), and 5.3% of C. tetragattii (n = 2) in 38 representative isolates that have been characterized. Mating type-specific PCR performed on 38 representative environmental and clinical isolates revealed that 16 (42.1%) were MAT a/ MATα hybrids, 17 (44.7%) were MATα, and five (13.2%) possessed MAT a mating type. We used conventional and NGS platforms to demonstrate a potential link between environmental and clinical isolates and lay a foundation to further describe mating patterns/history in Botswana.

Environmental pollution by hard-to-degrade polymers is on a steep rise and impacting the entire ecosystem. Microbial keratinases are pivotal in the breakdown of protein polymers that are otherwise resistant to most proteases. In this study, we isolated and identified bacteria from Sua pan soil through morphological, biochemical, and 16SrRNA sequencing approaches and further assessed these isolates for their keratinase production potential. Among the screened isolates, four bacteria, Bacillus cereus Bac 2, Bacillus sp. Bac 1, Pseudomonas aeruginosa Bac 3, and Achromobacter insuavis Bac 4, exhibited the highest degradation activity. B. cereus Bac 2 produced the widest clearance zone, whereas A. insuavis Bac 4 produced the narrowest clearance zone on feather meal agar. Protein bands observed in SDS-PAGE gels for the selected isolates further supported the presence of keratinolytic enzymes. We also investigated the effect of temperature and pH on keratinase activity and determined that all the keratinases were alkaline proteases, with B. cereus Bac 2, P. aeruginosa Bac 3, and Bacillus sp. Bac 1 showing maximum activity at a pH of 8.5, while A. insuavis Bac 4 had maximal activity at a pH of 8.0. Overall, our results indicated that B. cereus Bac 2 keratinase had significantly higher activity across all temperature and pH ranges investigated, compared to all the other isolates (p ≤ 0.0001). These findings highlight the potential application of bacterial isolates from alkalophilic environments, in the eco-friendly degradation of feather waste, as valuable by-products such as organic fertilizers, peptides, and amino acids.

The online version contains supplementary material available at 10.1007/s00284-026-04880-8.