Indigenous knowledge, nutririve and anticrobial properties of some wild mushrooms of Bunyoro Sub-region, Uganda.
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Uganda has a wide diversity of mushrooms, of which there has been little documentation on aspects of taxonomy, use including nutritive and pharmacological components. This study focused on four aspects of wild mushrooms: (1) inventory of the indigenous knowledge (2) determination of nutritive properties 3) determination of antimicrobial properties in selected wild mushrooms and (4) identification of the bioactive compounds in the most promising mushrooms Bunyoro Sub-region, Uganda. To achieve the study objectives, I undertook a social survey in the sub counties of Kyangwali, Kyabigambire and Nalweyo of Bunyoro Sub-region, Uganda. Standard analytical techniques following the AOAC were used to analyze for the mushroom proximate and mineral contents. Fatty acids, vitamins, and amino acids determinations followed the established protocols of the laboratories where the analyses were conducted. Selected medicinal wild mushrooms were screened using standard antimicrobial sensitivity assays against the bacterial strains- P. aeruginosa (ATCC 27853), S. aureus (ATCC 25923), S. aureus (MD), K. pneumoniae (ATCC 13883), K. pneumoniae MD, B. subtilis (ATCC 6633), E. coli (ATCC 25922), and a fungal strain, C. albicans (ATCC 10239). The potential bioactive compounds were identified using GC-MS. A total of 19 mushrooms species with 25 traditional names were mentioned. Fourteen species were identified, of which six were identified to genus level. Five species could not be identified. Sixteen species were edible and five were medicinal. The priority edible mushrooms were Termitomyces microcarpus, Termitomyces sp2, Termitomyces globulus, Termitomyces eurrhizus and Polyporus tenuiculus. The medicnal mushrooms were T. microcarpus, Termitomyces sp2, Pycnoporus sanguineus and Trametes sp. Women and respondents older than 50 years had more knowledge about mushrooms. Important medical illnesses, preparation and frequency of application of mushroom concoctions are described. The ash content in the studied mushrooms ranged between 11.2 and 16.87%, crude protein 11.56-27.42%, carbohydrate 37.12-61.05%, moisture 10.24-17.66%, dry matter 82.34-89.76% and energy 220.75-266.60 Kcal on dry weight basis. These chemical properties were significantly different between mushrooms (p < 0.05). In comparison with recommended daily intakes, the K, P, Mg Se, Mn, Cu and Fe contents were relatively higher unlike Ca, Zn and Na. Content of crude fat was low (2.02-3.79%) and dominated by unsaturated fatty acids. Termitomyces sp2 and T. globulus had abundant monounsaturated fatty acids and contained high levels of docosahexaenoic acid (DHA) (19.48%, 33%), respectively. This represents the first report on the occurrence of DHA in mushrooms. T. microcarpus had moderate levels of all groups of fatty acids. Palmitoleic acid was high followed by γ-linolenic, palmitic, α-linolenic and oleic acids. Stearic, DHA, linoleic and eicosapentaenic acids were detected in smaller quantities. Thiamin, folic acid, vitamin C, and niacin levels were high but below the recommended FAO references. Essential amino acid contents ranged between 23.6-59% of the total amino acids. Glutamic acid was high followed by phenylalanine, histidine, tryptophan and lysine. Leucine and valine were limited in T. globulus and T. eurrhizus, leucine, threonine and valine in P. tenuiculus, leucine in T. microcarpus and isoleucine and valine in Termitomyces sp2. The antimicrobial assays showed that the extracts exhibited moderate to high antibacterial activity especially against gram-positive bacteria. Petroleum ether extracts were more active than methanol ones. Isolated fractions exhibited great antimicrobial activity compared to crude extracts, but lower activity than the positive controls. T. microcarpus had comparable activity with tetracycline against S. aureus (ATCC 25923). Among the gram negative bacteria, P. aeruginosa was more sensitive to the mushroom fractions (Termitomyces sp2 and P. sanguineus), although the concentration needed to inhibit growth of this microbe was high (>200µg/ml). Phthalic acid derivatives (1,2-benzenedicarboxylic acid, bis(2-ethylhexyl)ester; 1,2- benzenedicarboxylic acid, dibutyl ester), several alkaloids, fatty acids (palmitic, linoleic, oleic acids) and 2-pentanone, 4-hydroxy-4-methyl were the major compounds identified in Termitomyces sp2. Several short and long-chain hydrocarbons, fatty acids/esters (palmitic, linoleic, oleic, stearic, methyl oleate, mystiric acids) and 2-pentanone, 4-hydroxy-4-methylwere identified in P. sanguineus; whereas fatty acids (palmitic, stearic acids), 2-pentanone, 4- hydroxyl-4-methyl- and 1-hexadecene in T. microcarpus. In conclusion, the study validates the ethno-mycological knowledge which may be important in the search of health and pharmaco-medicinal foods. Based on the human nutritional requirements set by FAO/WHO and Foood Nutrition Board, the studied mushrooms, when consumed in combination, have a high potential to supplement staple foods consumed by the poor communities in Uganda. It is anticipated that, in the future, the mushrooms will have an increasing importance in medicine and biotechnology because of their unique biosynthetic capabilities and metabolic products. Therefore, further studies should be done nationwide to document the indigenous knowledge to safe guard the knowledge handed down from generations. Considerable priority should be given to these mushrooms, particularly by nutritionists and in the pharmaceutical research-based studies that are engineered towards drug development.