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University of Johannesburg (2018)

Isolation and identification of bioactive compounds from bacterial endophytes associated with Combretum molle

Diale, Mamonokane Olga

Titre : Isolation and identification of bioactive compounds from bacterial endophytes associated with Combretum molle

Auteur : Diale, Mamonokane Olga

Université de soutenance : University of Johannesburg

Grade : Master’s Degree in Technology Biotechnology 2018

Résumé
Microbial infection remains a global concern. With the rapid increase of infectious diseases compounded with antimicrobial resistance, there is a need for novel and effective antimicrobial compounds. Plants host microorganisms known as endophytes, which can be either bacteria or fungi. These microorganisms synthesise numerous diverse compounds that are beneficial to the plant host by inhibiting growth of pathogenic microorganisms and promoting plant growth. Due to their biocontrol potential, research is now focusing on endophytes associated with medicinal plants. Endophytes associated with medicinal plants are known to produce similar secondary metabolites as their plant hosts which can be used in drug discovery and other industries. This project aimed at isolating and identifying bacterial endophytes from Combretum molle, a medicinal plant utilised for treatment of various diseases such malaria, fever, infertility in women and leprosy. Furthermore, the antimicrobial activity of crude extracts from its bacterial endophytes were tested against Gram-negative bacterial strains Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853 and Klebsiella oxytoca ATCC 13182 ; Gram-positive Staphylococcus aureus NCTC 6571 and Bacillus cereus ATCC 10876. The bacterial endophytes were isolated from surface sterilized leaves of C. molle obtained in Venda, Limpopo province (23°02’37.7"S 30°24’00.2"E). Five putative bacterial endophytes were identified using morphological data and the identity was confirmed by sequencing of the 16S rRNA gene, viz Lysinibacillus sp. HSRN, Staphylococcus sp. LCP, Enterobacter sp. SSRP1, Pseudomonas sp. SSRN1 and Bacillus sp. LRP. Four of the five endophytes showed antimicrobial activity against Bacillus cereus, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. Bacterial endophytes crude extracts and 80% methanol C. molle crude extracts were analysed by liquid chromatography mass spectrometry quadrupole time of flight (LC-MS QTOF). C. molle and its endophytes displayed production of numerous bioactive compounds some with antimicrobial activity. Similar compounds were detected from both C. molle and bacterial endophytes such as Kumatakenin, Qunic Aacid and Luteolin

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Page publiée le 17 février 2019