Showing papers in "Advances in Applied Microbiology in 1982"

Solid Substrate Fermentations

Abstract: Publisher Summary The solid-state fermentation refers to any fermentation that takes place on solid or semisolid substrate or that occurs in a nutritionally inert solid support, which provides some advantage to the microorganism with respect to access to nutrients. In a solid-state fermentation, several factors must be taken into consideration to achieve high efficiency of the overall process. Some of the general characteristics include: the solid substrate must be in a form to allow free circulation of air, usually the only other medium component required is water, and control of temperature is sometimes critical. Moisture content of the solid substrate is an important factor during microbial growth in a solid-state fermentation process. There are many advantages of the solid-state fermentation processes over the conventional stirred tank system on both laboratory and large scale. Some of the advantages for work involving fungi are—the medium is relatively simple, the conditions under which the fungus grows are more like the conditions in its natural habitat, and the desired product may be readily extracted from the vessel by addition of solvent directly.

Immobilized plant cells.

Abstract: Plant cells have been immobilized in alginate, where they have been shown to retain their biological activity. Such systems can be utilized for bioconversions.

Accumulation, metabolism, and effects of organophosphorus insecticides on microorganisms.

Abstract: Publisher Summary This chapter reviews the accumulation, metabolism, and effects of organophosphorus insecticides. These insecticides are taken up by the microorganisms directly or indirectly via food chains. The uptake of these compounds into microorganisms is favored by their high surface area to volume ratio. Different groups of microorganisms differ markedly in their ability to accumulate organophosphorus insecticides. Such insecticides are metabolized by microorganisms because of the microorganisms' capacity to hydrolyze, reduce, and oxidize these compounds. Parathion is one of the most commonly used organophosphorus insecticides. It is highly toxic to higher organisms. The effects of parathion on the growth of bacteria, fungi, and algae is shown to be dose dependent, with very low concentrations having no effect at all and higher concentrations drastically arresting the multiplication of the microorganisms. Parathion is known to inhibit the population growth of different microorganisms such as bacteria at high concentrations such as 200 ppm and 50,000 ppm.

Genetics and Biochemistry of Secondary Metabolism

Abstract: Publisher Summary Synthesis of a secondary metabolite is a highly ordered and coordinated event. The enzymes associated with secondary metabolites can be divided into four classes— (1) primary metabolism that yield the precursors of secondary metabolism, (2) those that are specific for the synthesis of the secondary metabolites, (3) those that provide energy or cofactors, and (4) those that further metabolize the produced metabolite. The formation of many secondary metabolites occurs by multistep processes catalyzed by multienzyme complexes that usually are produced only during a certain growth phase. Thus, some of the antibiotic-synthesizing enzymes are induced during a short period at the end of the logarithmic growth and the onset of the stationary phase. The genetics of secondary metabolism and sporulation is more complex than the genetics of growth because the expression of genes involved in these processes is superimposed on the expression of the logarithmic phase genes. Sporulation and secondary metabolism are favored under similar growth conditions.

Microbiology and Biochemistry of Miso (Soy Paste) Fermentation

Abstract: Publisher Summary Miso is made by a two-stage fermentation process. The first stage involves the production of the koji from cooked grains inoculated with Aspergillus oryzae. This is followed by a second fermentation (the moromi) where the koji is mixed with salt, cooked soybeans, and appropriate inoculums. The different types of miso are made by mixing different amounts of raw materials. The precise proportions of the raw materials used, depends on the type of miso being made. The predominant carbohydrate in miso is glucose. Almost all types of miso contain about 9–15% crude protein. Although koji preparation, indispensable for making miso, has been simplified by the use of rotary cookers, the process still requires a well-trained operator. A new type of low-salt and high-protein miso is produced by mixing enzymatically hydrolyzed, defatted soybeans with ordinary salty red miso, followed by short-term ripening. Such miso contains 53% moisture, 6.3% sodium chloride, and 17.6% protein.

Partition affinity ligand assay (PALA): applications in the analysis of haptens, macromolecules, and cells.

Abstract: Publisher Summary The partition affinity ligand assay (PALA) method is normally used as a nonequilibrium method, that is, the binding reaction involved does not have to reach equilibrium. A requirement for a binding assay in aqueous two-phase systems is that the reactants in the binding reaction must have markedly different partition coefficients. The PALA principle includes incubation of the reaction mixture and subsequent separation with an added phase system, both steps being carried out in a single test tube. No separate washing steps and centrifugations are needed. In a direct binding assay, the binding between two different molecules is utilized to quantify one of them. Sufficiently concentrated aqueous solutions of some water-soluble polymers, forming phase systems, can be used for selective distribution of macromolecules. Such phase systems have a top phase rich in one of the polymers and a bottom phase rich in the other. Compared to the phase systems generally used in chemistry, that is, those containing organic solvents, such water-rich systems have been shown to be better for separating biological material.