Vegetative compatibility and phenotypic characterization as a means of determining genetic diversity of Aspergillus flavus isolates.

Toxigenic Aspergillus species produce mycotoxins that are carcinogenic, hepatotoxic and teratogenic immunosuppressing agents in both human and animals. Kenya frequently experiences outbreaks of aflatoxicosis with the worst occurring in 2010, which resulted in 215 deaths. We examined the possible reasons for these frequent aflatoxicosis outbreaks in Kenya by studying Aspergillus flavus diversity, phenotypes and mycotoxin profiles across various agricultural regions. Using diagonal transect random sampling, maize kernels were collected from Makueni, Homa Bay, Nandi, and Kisumu counties. Out of 37 isolates, nitrate non-utilizing auxotrophs complementation test revealed 20 vegetative compatibility groups. We designated these groups by the prefix "KVCG", where "K" represented Kenya and consequently assigned numbers 1-20 based on our findings. KVCG14 and KVCG15 had highest distribution frequency (n = 13; 10.8 %). The distribution of the L-, S- and S-/L-morphotypes across the regions were 57 % (n = 21); 7 % (n = 3) and 36 % (n = 13), respectively. Furthermore, a unique isolate (KSM015) was identified that had characteristics of S-morphotype, but produced both aflatoxins B and G. Coconut agar medium (CAM) assay, TLC and HPLC analyses confirmed the presence or absence of aflatoxins in selected toxigenic and atoxigenic isolates. Diversity index (H') analyses ranged from 0.11 (Nandi samples) to 0.32 (Kisumu samples). Heterokaryon compatibility ranged from 33 % (for the Makueni samples, n = 3) to 67 % (Nandi samples, n = 6). To our knowledge, this is the first reported findings for A. flavus diversity and distribution in Nandi, Homa Bay and Kisumu counties and may assist current and future researchers in the selection of biocontrol strategies to mitigate aflatoxin contamination as has been researched in Makueni and neighbouring counties.

Evidence of Heterokaryon compatibility on Candida albicans biofilm

Aims: Candida species, especially Candida albicans, are frequently found associated with biomaterials and immunosuppressed patients, and have been described as the most virulent yeasts in human fungi diseases. These yeasts have recently been isolated from periodontal pockets, revealing the penetration of hyphae into the periodontal connective tissue. Methods: In this study, 7 periodontal C. Albicans strains were applied individually in biofilm development on titanium discs and the samples were thereafter analyzed as for the number of colony forming units per milliliter (CFU/mL), dry-weight and scanning electron microscopy (SEM). Results: Counting of CFU/ mL and determination of dry-weight showed that all samples formed biofilm. SEM analysis showed the development of a polymorphic network in the biofilms and the presence of hyphal anastomosis in the sites where fusion between the hyphae occurred. Conclusion: periodontal C. albicans strains present heterokaryon compatibility.