The current status of natural products from marine fungi and their potential as anti-infective agents

A growing number of marine fungi are the sources of novel and potentially life-saving bioactive secondary metabolites. Here, we have discussed some of these novel antibacterial, antiviral, antiprotozoal compounds isolated from marine-derived fungi and their possible roles in disease eradication. We have also discussed the future commercial exploitation of these compounds for possible drug development using metabolic engineering and post-genomics approaches.

Application of immobilized growing cells

Immobilized living and growing cells are attracting worldwide attention because these biocatalysts have self-proliferating and self-regenerating properties of catalytic systems and are able to catalyze efficiently multifunctional and multistep reactions involving coenzyme regeneration. This article summarizes the application of microbial, plant, and mammalian cells, genetically improved or not, immobilized by different methods to the production of amino acids, organic acids, antibiotics, steroids, medicines, enzymes, bioactive peptides, etc., emphasizing the recent results. Effects of the gel properties on the efficient performance of bioprocesses are also discussed.

Dynamic response of immobilized cells to pulse addition of L-valine in cyclosporin A biosynthesis

A feeding strategy for L-valine was tested in the production of cyclosporin A (Cy A), a powerful immunosuppressive secondary metabolite, in celite-immobilized cells of the fungus Tolypocladium inflatum. This system has been previously shown to have promise over conventional submerged systems. Significant increase in Cy A biosynthesis was manifested in the immobilized cells when L-valine was added at 108 h (system C) and at 156 h (system D) during the exponential growth phase. However, no clearly stimulating effect of L-valine on Cy A titre was observed when the amino acid was supplemented at hour 60 (lag phase, system B) or when the valine was present from the start (system A), where system A = 100%, system B = 113%, system C = 253%, system D = 302%. The large contribution to the enhanced production of Cy A in systems C and D may be explained by the preferential channeling of L-valine to growth during the lag phase and to secondary metabolism during the late exponential phase of the immobilized cells.

On the merits of viable-cell immobilisation

Many advantages have been claimed over the years for the use of immobilised cells, both as enzyme systems and as whole viable cell systems for complete fermentation reactions. However, few of the claims have been fully substantiated, and may not even be entirely justified. Most research is involved with single applications and the best that can be hoped for is some evidence that immobilised cells in each of these individual cases display some advantage over the equivalent free cell system. The purpose of this review is to assess the merits of viable cell immobilisation in the light of published literature and to elucidate the underlying mechanisms. Particular attention is paid to the generally unanticipated, but widely observed enhanced stability of immobilised cell fermentation processes.