Trends in bioconversion of lignocellulose: Biofuels, platform chemicals & biorefinery concept

Recent advances in lactic acid production by microbial fermentation processes

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.

Halotolerant or halophilic microorganisms, able to live in saline environments, offer a multitude of actual or potential applications in various fields of biotechnology. The technical applications of bacteriorhodopsin comprise holography, spatial light modulators, optical computing, and optical memories. Compatible solutes are useful as stabilizers of biomolecules and whole cells, salt antagonists, or stress-protective agents. Biopolymers, such as biosurfactants and exopolysaccharides, are of interest for microbially enhanced oil recovery. Other useful biosubstances are enzymes, such as new isomerases and hydrolases, that are active and stable at high salt contents. Halotolerant microorganisms play an essential role in food biotechnology for the production of fermented food and food supplements. The degradation or transformation of a range of organic pollutants and the production of alternative energy are other fields of applications of these groups of extremophiles.

Potential of halotolerant and halophilic microorganisms for biotechnology.

Production of bioethanol from sugarcane bagasse: status and perspectives.

Production of acidic lipase by Aspergillus niger in solid state fermentation

Strain improvement of Penicillium janthinellum NCIM 1171 for increased cellulase production.

Polysaccharides from bagasse: applications in cellulase and xylanase production

Purification and characterization of acidic lipase from Aspergillus niger NCIM 1207.

Enzymatic hydrolysis of delignified bagasse polysaccharides

K.B. Bastawde

Papers

Production of acidic lipase by Aspergillus niger in solid state fermentation

Strain improvement of Penicillium janthinellum NCIM 1171 for increased cellulase production.

Polysaccharides from bagasse: applications in cellulase and xylanase production

Purification and characterization of acidic lipase from Aspergillus niger NCIM 1207.

Enzymatic hydrolysis of delignified bagasse polysaccharides