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

Biotechnological potential of coffee pulp and coffee husk for bioprocesses

Publisher Summary This chapter discusses the physiology and biotechnology of Aspergillus species. The genus Aspergillus is found worldwide and consists of more than 180 officially recognized species. Molecular and genetic studies of Aspergillus species tend to concentrate on four thoroughly investigated species: A. nidulans, A. niger, A. oryzae, and A. fumigatus. The physiology of the Aspergillus such as life cycle, physiological responses and signal transductions, and carbon and nitrogen metabolisms are presented in this chapter. Most Aspergillus species, except A. fumigatus, have both sexual and asexual processes for spore duplication. A few, including A. nidulans, are also able to reproduce via a parasexual cycle. The capacities of microbial species to survive and respond physiologically to changes in their environment enable these species to exist under a broad range of conditions. Several signaling pathways are involved in Aspergillus cell growth and differentiation, and indicate links between cell developments to metabolite biosynthesis. The molecular biology of Aspergillus is also explained with the help of its gene expression, and by discussing the molecular biology approach of production of protein by Aspergillus species. The chapter presents the industrial application of the Aspergillus species such as citric acid production, production of extracellular enzymes, role of Aspergillus in the process of biotransformation, production of secondary metabolites, environmental applications, and production of other industrial products.

Physiology and Biotechnology of Aspergillus

Fructooligosaccharides (FOS) are prebiotic substances found in several vegetable or natural foods. The main commercial production of FOS comes from enzymatic transformation of sucrose by the microbial enzyme fructosyltransferase. The development of more efficient enzymes, with high activity and stability, is required and this has attracted the interest of biotechnologists and microbiologists with production by several microorganisms being studied. This article reviews and discusses FOS chemical structure, enzyme characteristics, the nomenclature, producer microorganisms and enzyme production both in solid state fermentation and submerged cultivation.

Microbial production of fructosyltransferases for synthesis of pre-biotics

Summary Polygalacturonases (PGases) or hydrolytic depolymerases are enzymes involved in the degradation of pectic substances. They have a wide range of applications in food and textile processing, degumming of plant rough fibres and treatment of pectic wastewaters. Bacteria, yeasts and fungi under both submerged (SmF) and solid-state fermentation (SSF) conditions produce these enzymes. Bacteria produce mainly alkaline and thermostable PGases, whilst fungi are the major producers of acidic PGases. In order to obtain high yields of pectinase production, strain improvement and optimization of culture conditions should be considered. This review is an overview of the microorganisms, substrates, and type of culture used for PGase production. It also provides a description about the strategies used to enhance the production of PGases.

A. Minjares

Papers

New approach for selecting pectinase producing mutants of Aspergillus niger well adapted to solid state fermentation.