Bioactive Compound Produced by Endophytic Fungi Isolated FromPelargonium sidoidesAgainst Selected Bacteria of Clinical Importance

Abstract

Endophytic fungi have the ability to live inside the host plant tissues without causing neither symptoms of diseases/or harm. Opportunistic infections are accountable for majority of the outbreaks, thereby putting a burden on the health system. To investigate and characterize the bioactive compounds for the control of bacteria of clinical importance, extracts from endophytic fungi were isolated from indigenous South African medicinal plants. Extracts from endophytic fungi were isolated from 133 fungal strains and screened against Gram positive and negative bacteria namely Bacillus cereus, Escherichia coli, Enterococcus faecium, and E. gallinarum using disk diffusion. Furthermore, gas chromatography–mass spectrometry was performed to identify the bioactive compounds. Sixteen out of one hundred and thirty-three (12%) fungi extracts exhibited antibacterial properties against some of the selected bacteria. E. coli was found to be the most susceptible in contrast to E. faecium and E. gallinarum which were the most resistant. The isolate MHE 68, identified as Alternaria sp. displayed the greater spectrum of antibacterial activities by controlling selected clinical bacteria strains including resistant E. faecium and E. gallinarum. The chemical analysis of the extract from MHE 68 indicated that linoleic acid (9,12-octadecadienoic acid (Z,Z)) and cyclodecasiloxane could be accountable for the antibacterial activity. This is the first study conducted on the secondary metabolites produced by endophytic fungal strains isolated from the Pelargonium sidoides DC. possessing antibacterial properties.

Isolation and Characterization of Fungal Endophytes Isolated from Medicinal Plant Ephedra pachyclada as Plant Growth-Promoting

“…The IDZ values are identified based on inhibition zones where the clear zones are less than 10 mm, which are known as low activity, while IDZ values from 10 to 20 mm are considered of medium activity and IDZ values greater than 20 mm are considered to be highly active [ 48 ]. Similarly, Manganyi et al [ 49 ] reported that among 133 endophytic fungi isolated from healthy roots and leaves of medicinal plant Pelargonium sidoides , only the crude extract of sixteen fungal strains showed antibacterial activity against Bacillus cereus, Enterococcus faecium, E. coli , and Enterococcus gallinarum . Moreover, the ethyl acetate extract of five endophytic fungal strains isolated from Nigerian plants Ocimum gratissimum, Newbouldia laevis, and Carica papaya displayed antibacterial activity against Gram-positive and Gram-negative bacteria, while they did not exhibit any antifungal activity against Candida albicans and Aspergillus fumigatus [ 50 ].…”

Biologically Active Secondary Metabolites from Endophytic Alternaria Species

“…MHE 68 isolated from Pelargonium sidoides yielded cyclodecasiloxane (15) which exhibited a potent broad-spectrum antibacterial activity including drug-resistant enterococcal strains, viz. Enterococcus faecium and Enterococcus gullinarum (Manganyi et al 2019 ). Another endophytic isolate of Alternaria isolated from Schinus terebinthifolius , Alternaria alternata LGMF626 exhibited a potent anti-MRSA activity with an MIC of 18.52 μg/mL of the cell-free extract.…”

Pharmacological Potential of Fungal Endophytes Associated with Medicinal Plants: A Review

“…Therefore, the biotechnological application of fungal endophytes in agriculture and industries in the derivation of salient natural plant products became necessary. The discovery of new metabolic compounds from medicinal plants and associated fungi has been documented in several research findings [ 16 , 17 , 18 ]. Currently, Pelargonium sidoides has been recognized as the most invaluable medicinal plant used traditionally in primary health care in South Africa and research on the antibacterial properties of the diverse endophytic fungal extract from Pelargonium sidoides DC has been documented [ 17 ].…”