In the early 1980s, there were occasional reports of natural products isolated
from marine invertebrates that were either identical to compounds from terrestrial
sources, or were close chemical relatives. Since that time period it has become evident
that microbes, whether they can currently be fermented under “normal conditions” or
require genetic analyses and subsequent elaboration in surrogate hosts etc., are very
heavily involved in the production of marine invertebrate secondary metabolites.
In the last few years, the situation with plant-derived natural products is very
reminiscent of the early 1980s / marine invertebrate stories, as there are now significant
numbers of reports invoking microbes (usually endophytic fungi), in the production of
nominally plant-derived natural products. In one particular case, that of maytansine, the
production by epiphytic root bacteria in the nominal producing plant is definitive.
Each issue of current journals covering genetic analyses of plants or marine
invertebrates, often contains at least one article (basic science or review), that furthers
the potential involvement of microbes in the production of even well-known molecules
such as taxol, vinca alkaloids, homoharringtonine on the plant side and pederin-related
(e.g. onnamide) derivatives on the marine side. We will also give information on
bacterial, fungal and algal interactions that together lead to the production of natural
products, though the exact involvement may not yet be known. We will broadly discuss
the current situation and then hone in on areas where microbial involvement is
definitive, and give the evidence for areas where it is still circumstantial.
Keywords: Biosynthesis, Biosynthetic gene clusters, Bioactive agents, Coculture,
Endophyte, Microbial interactions, Natural products, Sequencing,
Symbiont, Unculturable.
