A FUNCTIONAL APPROACH TO INVESTIGATE CULTIVABLE HUMAN ORAL MICROBIOME: EXAMPLES OF FIRMICUTES AND YEASTS
Rawia Mekki Hammad Mohammed1, Mona Ali Magrabi Mohammed1, Hajer Suleiman Hamdan Teia1, Sara Mohammed Ali Mohammed1, Faisal Hammad Mekky Koua2,3
1Department of Biology & Biotechnology, Faculty of Science & Technology, Al Neelain University, El-Baladiya Ave, PO Box 12702, Khartoum, Sudan. 2National University Research Institute-NURI, National University-Sudan, Air St, PO Box 3783, Khartoum, Sudan. 3Department of Biochemistry & Molecular Biology, Faculty of Science & Technology, Al Neelain University, El Baladiya Ave, PO Box 12702, Khartoum, Sudan.
Background and aim: Human oral microbiome is the total microbes and/or their genomic content that are harbored within a human mouth. They can be assessed by culture dependent and/or culture-independent methods. Here, we adopted a culture dependent method to unravel the cultivable firmicutes and the yeast Candida albicans of the human oral cavity. Methods: A comprehensive sampling method established during this study was used to collect samples from 11 donors and cultivated on selective media for firmicutes and C. albicans isolation followed by isolates identification using conventional microbiological techniques. Results: As a result, 24 bacteria isolates were identified and classified as firmicutes and related strains from actinobacteria with 96% and 4%, respectively. The assignments have resulted in 52.9% staphylococci, 41.2% bacilli and 4% clostridia, as well as micrococcus. On the other hand, 9 isolates of yeasts were identified as C. albicans. The majority of firmicutes were tolerant, while the staphylococci were mostly drug resistant especially toward tetracycline, lincomycin and cloxacillin. When co-cultured against each other, the B. mycoides isolates affected the growth of S. aureus, which is itself affected the growth of other staphylococci. Except the clostridium isolates, most of the isolates are salt tolerant up to 3.4 M NaCl. C. albicans growth was limited by >1.7 M NaCl as well as low temperature (<10 ºC). It exerts tolerance against clotrimazole and moderate susceptibility to nystatin antifungal drugs. Excessive phylogenetic analysis revealed more insights into the diversity of oral microbes. Conclusion: Further, genomic characterization for the B. mycoides and C. albicans will be considered in order to have a complete picture on these oral microbiome isolates and their interactions with other microbes residing the human oral cavity.