Microbes have made a phenomenal contribution to the health and well-being of people throughout the world. In addition to producing many primary metabolites, such as amino acids, vitamins and nucleotides, they are capable of making secondary metabolites, which constitute half of the pharmaceuticals on the market today and provide agriculture with many essential products. This review centers on these beneficial secondary metabolites, the discovery of which goes back 80 years to the time when penicillin was discovered by Alexander Fleming.

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Microbial drug discovery: 80 years of progress

Recent advances in solid-state fermentation.

Application of solid-state fermentation to food industry—A review

Starting with a brief history of solid-state fermentation (SSF), major aspects of SSF are reviewed, which include factors affecting SSF, biomass, fermentors, modeling, industrial microbial enzymes, organic acids, secondary metabolites, and bioremediation. Physico-chemical and environmental factors such as inoculum type, moisture and water activity, pH, temperature, substrate, particle size, aeration and agitation, nutritional factors, and oxygen and carbon dioxide affecting SSF are reviewed. The advantages of SSF over Submerged Fermentation (SmF) are indicated, and the different types of fermentors used in SSF described. The economic feasibilities of adopting SSF technology in the commercial production of industrial enzymes such as amylases, cellulases, xylanase, proteases, phytases, lipases, etc., organic acids such as citric acid and lactic acid, and secondary metabolites such as gibberellic acid, ergot alkaloids, and antibiotics such as penicillin, cyclosporin, cephamycin and tetracyclines are highlighted. The relevance of applying SSF technology in the production of mycotoxins, biofuels, and biocontrol agents is discussed, and the need for adopting SSF technology in bioremediation of toxic compounds, biological detoxication of agro-industrial residues, and biotransformation of agro-products and residues is emphasized.

Solid-State Fermentation Systems—An Overview

https://repositorium.sdum.uminho.pt/bitstream/1822/16854/1/3587.pdf

Bioactive phenolic compounds : production and extraction by solid-state fermentation. A review

Despite the increasing number of publications dealing with solid-state (substrate) fermentation (SSF) it is very difficult to draw general conclusion from the data presented This is due to the lack of proper standardisation that would allow objective comparison with other processes Research work has so far focused on the general applicability of SSF for the production of enzymes, metabolites and spores, in that many different solid substrates (agricultural waste) have been combined with many different fungi and the productivity of each fermentation reported On a gram bench-scale SSF appears to be superior to submerged fermentation technology (SmF) in several aspects However, SSF up-scaling, necessary for use on an industrial scale, raises severe engineering problems due to the build-up of temperature, pH, O2, substrate and moisture gradients Hence, most published reviews also focus on progress towards industrial engineering The role of the physiological and genetic properties of the microorganisms used during growth on solid substrates compared with aqueous solutions has so far been all but neglected, despite the fact that it may be the microbiology that makes SSF advantageous against the SmF biotechnology This review will focus on research work allowing comparison of the specific biological particulars of enzyme, metabolite and/or spore production in SSF and in SmF In these respects, SSF appears to possess several biotechnological advantages, though at present on a laboratory scale only, such as higher fermentation productivity, higher end-concentration of products, higher product stability, lower catabolic repression, cultivation of microorganisms specialized for water-insoluble substrates or mixed cultivation of various fungi, and last but not least, lower demand on sterility due to the low water activity used in SSF

Biotechnological advantages of laboratory-scale solid-state fermentation with fungi.

During the last decade, significant effort has been made to apply computational and physical methods to solid-state fermentation (SSF). This had positive impact both on our understanding of the basic principles underlying this old technology, and on the latest progress made in industrial bioengineering. Guidelines on bioreactor design and operation including scale-up, new methods for biomonitoring and advanced control strategies are among the most important outcomes of practical use. Nevertheless, there still is a lack of experimental data, which hampers parameter identification and thus broader use of mathematical modeling. More attention should therefore be paid to combining and concentrating modern physical techniques and computational approaches in order to allow better model validation and thus further progress in rational bioengineering of SSF.

J. Lenz

Papers

Biotechnological advantages of laboratory-scale solid-state fermentation with fungi.

A survey of computational and physical methods applied to solid-state fermentation.