Abstract
M.Tech. (Biotechnology)
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.