Advantages and Progress Innovations of Solid-State Fermentation to Produce Industrial Enzymes

Abstract

Industrial enzymes are biocatalysts that are commercially used in a variety ofcommercial sectors such as pharmaceuticals, chemical production, biofuels, food and beverages, and consumer products. Due to advancements in recentyears, biocatalysts are considered more economical than use of whole cells andcan be used as a unit operation within a process to generate the desired productof interest. Industrial biological catalysis through enzymes has experienced rapidgrowth in recent years due to their ability to operate at mild conditions, highspecificity, and high productivity. Industrial enzymes can be produced by bothsubmerged fermentation (SmF) and solid-state fermentation (SSF). In contrast tothe first process, the second bioprocess (SSF) is the cultivation of microorganismsunder controlled conditions in the absence of free water. Examples of bioproductsof SSF include industrial enzymes, fuels, and nutrient-enriched animalfeeds. Most industrial enzymes are manufactured using the traditional bioprocessof SmF, where microbial cells are suspended in a large volume of water thatis stirred and aerated using mechanical devices; such culture conditions dictatethe overall physiological behavior of microorganisms provoking biochemicaland structural changes affecting the quantity and activity of biocatalysts produced.Among the main advantages of SSF over SmF is a higher volumetricproductivity, secretion facilities to get extracellular bioproducts with higher stability,being usually simpler with lower energy requirements, resembling of thenatural habitat of some microorganisms, and easier downstream processing. Inthis chapter we summarize, compare, analyze, and discuss the technological,biochemical, and microbiological advantages of SSF to produce industrialenzymes. Furthermore, culture conditions, aggregation and diffusional phenomena,bioreactors, genetic expression, and protein regulation are covered.