Screening Fungal Endophytes Derived from Under-Explored Egyptian Marine Habitats for Antimicrobial and Antioxidant Properties in Factionalised Textiles

Abstract

Marine endophytic fungi from under-explored locations are a promising source for the discovery of new bioactivities. Different endophytic fungi were isolated from plants and marine organisms collected from Wadi El-Natrun saline lakes and the Red Sea near Hurghada, Egypt. The isolated strains were grown on three different media, and their ethyl acetate crude extracts were evaluated for their antimicrobial activity against a panel of pathogenic bacteria and fungi as well as their antioxidant properties. Results showed that most of the 32 fungal isolates initially obtained possessed antimicrobial and antioxidant activities. The most potent antimicrobial extracts were applied to three different cellulose containing fabrics to add new multifunctional properties such as ultraviolet protection and antimicrobial functionality. For textile safety, the toxicity profile of the selected fungal extract was evaluated on human fibroblasts. The 21 strains displaying bioactivity were identified on molecular basis and selected for chemical screening and dereplication, which was carried out by analysis of the MS/MS data using the Global Natural Products Social Molecular Networking (GNPS) platform. The obtained molecular network revealed molecular families of compounds commonly produced by fungal strains, and in combination with manual dereplication, further previously reported metabolites were identified as well as potentially new derivatives.

Antimicrobial and Antibiofilm Activities of the Fungal Metabolites Isolated from the Marine Endophytes Epicoccum nigrum M13 and Alternaria alternata 13A

“…Moreover, all the other tested compounds showed a range of moderate, weak or no effect against the tested Gram-negative bacteria and C. albicans . This finding could be attributed to the loss (through isolation) of synergistic effects of the major and minor molecules present in the total fungal extract of E. nigrum M13 or A. alternata 13A which exhibited more promising results than the pure compounds alone, which is consistent with a previous study in the literature [ 37 ] and our own previous research [ 18 ].…”

“…Out of the 21 endosymbiotic marine-derived fungal isolates recovered and prioritized in our previous study, we have selected the isolates M13 and 13A for scale up due to their promising antimicrobial effects and prolific chemical profiles established by the LC-HRMS analysis. The fungal strains M13 and 13A were isolated from the marine seagrass Thalassia hemprichii (collected from Makady bay, south Hurghada, Egypt) and the plant Phragmites australis (collected from Lake El-Bida, Wadi El-Natrun, Egypt) and identified using morphological features and genetic markers (ITS rDNA and β-tubulin) as Epicoccum nigrum and Alternaria alternata , respectively, as described previously [ 18 ].…”

“…If left unattended, diseases associated with drug-resistant pathogens could kill more people than cancer [ 31 ]. For the discovery of new antimicrobial agents from natural sources that could be efficient in the incorporation of textiles, we have performed initial antimicrobial screening which indicated that the total extract of each of M13 and 13A exhibited promising antimicrobial effects against a panel of pathogenic strains tested [ 18 ]. The antimicrobial activity of the pure compounds ( 1 – 6 ) of E. nigrum M13 and compounds ( 7 – 16 ) of A. alternata 13A was assessed against a panel of pathogenic microorganisms comprising Gram-positive bacteria ( Staphylococcus aureus and Bacillus subtilis ), Gram-negative bacteria ( Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumonia, and Proteus vulgaris ), and yeast ( Candida albicans ) ( Table 3 ).…”

“…The fungal strain M13 was obtained from Thalassia hemprichii leaves collected from Makady bay, South Hurghada, Red sea, Egypt and identified as Epicoccum nigrum based on its morphological features, together with ITS rDNA (GenBank accession number MK953943) and β-tubulin (GenBank accession number MT184348) phylogenetic analysis [ 18 ]. Strain 13A was isolated from the leaves of Phragmites australis collected from Lake El-Bida, Wadi El-Natrun depression, Beheira Governorate, Egypt, and identified as Alternaria alternata based on its morphological characteristics and its ITS rDNA sequence (GenBank accession number MK248606) [ 18 ].…”

“…In 2017, we initiated a collaborative project between Egypt and the UK aiming at the isolation of new endophytic fungal strains from different under-explored marine habitats in Egypt to be screened for their antimicrobial effect, with the ultimate aim of incorporating their bioactive extracts or metabolites into textiles used in Egyptian hospitals to reduce nosocomial infections. As a result, 21 out of 32 endosymbiotic marine-derived fungal isolates were isolated from both Hurghada, Red Sea and Wadi El-Natrun depression in Sahara, identified by molecular biological traits, and selected for further study based on their antimicrobial effects [ 18 ]. In this study, the chemical profiles following large scale fermentation of two endophytic fungal isolates, Epicoccum nigrum M13 isolated from the seagrass Thalassia hemprichii collected from Hurghada, Red sea and Alternaria alternata 13A recovered from the leaves of Phragmites australis collected from Wadi El-Natrun depression were studied.…”