Mangrove endophytic fungi from Sarawak: isolation of secondary metabolites and optimisation of growth conditions

Endophytic fungi are a group of organisms unique in the sense that they live virtually their entire life cycles within the tissues of a host; they have been known to confer beneficial properties to the plants they inhabit in terms of protection from predation and tolerance against abiotic stress. For all their unique properties, much work lies ahead in understanding these innocuous organisms. Mangrove endophytic fungi are the more interesting group within endophytes, this as they have adapted to not only the host plant but the extreme environment those mangrove plants are constantly subjected to. There has been limited work in Malaysia regarding mangrove endophytic fungi, with more focus being given to fungi which are associated to medicinal plants. Nevertheless, significant work has been done by countries which border the South China Sea. These works were reviewed in a bid to understand trends in mangrove endophytic fungi research on a regional scale. During the course of this research mangrove endophytic fungi were subjected to large scale fermentation to isolate natural products, as well as growth optimisation studies to discern the best growth medium for isolation and cultivation of these extreme-tolerant microbes. The well-known antioxidant trans-ferulic acid was successfully isolated from a batch of fermentation products from Phyllosticta-related strain of fungi. It appears to be the first known instance of finding this metabolite with the fungal genus tested. Growth optimisation studies revealed that the growth requirements of each strain of fungi significantly differs from each other. Salinity, nitrogenous compounds, pH, are all important factors to consider when optimising growth of mangrove endophytic fungi. Though the strains tested were limited in number and diversity, it is clear that follow-up studies will be required to reveal more about the growth behaviour of these poorly-studied life forms.