Yeasts and Fungi

Although these have been less exhaustively investigated than their bacterial counterparts, the results of these investigations have revealed a number of signihcant features  

The degradation of chlorinated phenols has been examined with the white-rot basidiomy-cete Phanerochaete chrysosporium under conditions of nitrogen limitation, and apparently involves both lignin peroxidase and manganese-dependent peroxidase activities (Valli and Gold 1991). 

Essentially similar reactions are involved in the degradation of 2,4,5-trichlorophe-nol, and this is accomplished more rapidly—possibly due to less interference from 

FIGURE 9.24 NIH shift during the metabolism of 2,4-dichlorophenoxyacetate hy Aspergillus niger. 

4- dichlorophenol, and forms 2-chloro-l,4-dihydroxybenzene that is converted by alternative pathways to 1,2,4-trihydroxybenzene before ring cleavage (Reddy et al. 1998). Parenthetically, a formally comparable sequence of reactions is used for the degradation of 

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Other Nitrogen Compounds. The basis of the sophisticated nitrogen compounds Hsted in Table 10 is the reaction of formaldehyde with amino compounds. A significant amount of Hterature details investigation of the mechanism of action, particularly whether or not the antimicrobial activity depends on decomposition to formaldehyde (40—42). These compounds tend to have substantial water solubiUty and are more effective against bacteria than fungi and yeasts. Key markets for these compounds are metalworking fluids, cosmetics, and in-can preservation of paints (see Alkanolamines Amines, fatty amines). 

Sodium benzoate is another preservative used in shampoos. It kills bacteria, fungi, and yeasts, and works well in acidic mixtures. 

Trehalose Fungi and yeasts. The major sugar of insect hemolymph. ... 

This section considers, in three separate chapters, the anatomy and physiology of bacteria, fungi and yeasts, and viruses, together with a survey of the characters of individual members of these groups likely to be of importance to the applied field covered by this book. Additional information is provided about more rapid methods for detecting bacteria. The final chapter in this section (Chapter 4) considers the principles of microbial pathogenicity and epidemiology. 

Eukaryotic Microorganisms Fungi and Yeasts Metabolism by Fungi... 

Total bacteria Total fungi and yeasts Pseudomonas species Enterobacteriaceae Spore formers... 

The types of microorganisms found in various products are Pseudomonas species, including Pseudomonas aeruginosa, Salmonella, species, Staphylococcus aureus, and Escherichia coli. The USP and other pharmacopoeias recommend certain classes of products to be tested for specified microbial contaminants, e.g., natural plant, animal, and some mineral products for the absence of Salmonella species, suspensions for the absence of E. coli, and topically administered products for the absence of P. aeruginosa and S. aureus. Emulsions are especially susceptible to contamination by fungi and yeasts. Consumer use may also result in the introduction of microorganisms. For aqueous-based products, it is therefore mandatory to include a preservative in the formulation in order to provide further assurance that the product retains its pharmaceutically acceptable characteristics until it is used by the patient. 

A comparison of the mean amino acid composition of the soils with those of algae, bacteria, fungi, and yeasts showed the greatest similarity to that of bacteria. [4] This suggests, perhaps not too surprisingly, a major role for microorganisms in the synthesis in the soil of amino acids, peptides and proteins from plant and animal residues, and also explains the relatively uniform amino acid composition in different soils. 

Other Life Forms Viruses, Fungi, and Yeasts... 

Fungi and yeasts are also members of the marine heterotrophic eukaryotes. They are generally found living on or within tissues of other organisms or on detrital POM. Fungi are important primarily in coastal water where they serve as decomposers of terrestrial vascular plant detritus. Yeasts occur as parasites of copepods. 

Lowery CE Jr, Foster JW, Jurtshuk P. 1968. The growth of various filamentous fungi and yeasts on n-alkanes and ketones I. Studies on substrate specificity. Arch Mikrobiol 60 246-254. 

While gallic acid is probably utilized by fungi and yeasts as a carbon source, only a few papers have suggested this possibility (25,40,41), including one for Aspergillus flavus (42). 

Xylanase production has been reported to occur in a wide spectrum of organisms. Although absent in vertebrate animals, xylanases are produced in many forms of bacteria, fungi and yeasts, crustaceans, algae and plant seeds. Current interest in xylanases has been focused primarily on the enzymes produced by fungi and bacteria and, to a lesser extent, yeasts. The high yields and relative ease of production have made these systems the most promising for future commercialization. 

Currently, chitosan has been approved as a food additive in Korea and Japan since 1995 and 1983, respectively (KFDA, 1995 Weiner, 1992), and is mostly applied as a food additive or preservative and as a component of packaging material. In addition, the antimicrobial characteristics of chitosan present a profitable potential for developing functional food ingredients however, they may prove to be useful in nutraceuticals for the ability to stimulate host defenses against a variety of bacteria, fungi, and yeast (Lim and Hudson, 2003). 

Vitamin D2 (ergocalciferol) is formed by the photoconversion of ergo-sterol, a sterol present in certin fungi and yeasts, and differs from cholecalciferol in having an extra methyl group at carbon 24 and an extra double bond between C22 and C23. Ergocalciferol was widely used for many years as a therapeutic agent. 

Gadd,G. M. (1990a). Fungi and yeasts for metal accumulation. In Microbial Mineral Recovery, ed. H.L. Ehrlich C. L. Brierley, pp. 249-75. New York McGraw-Hill. 

Ergosterol 18 Major sterol of fungi and yeast Chlorella vulgaris 0.3 Skinl [36,37]... 

Vitamin D is represented by cholecalciferol (vitamin D3) and ergocalciferol (vitamin D2), which are structurally similar secosteroids derived from the UV irradiation of provitamin D sterols. In vertebrates, vitamin D3 is produced in vivo by the action of sunlight on 7-dehydrocholesterol in the skin. Vitamin D2 is produced in plants, fungi, and yeasts by the irradiation of ergosterol. On irradiation, the provitamins are converted to previtamin D, which undergoes thermal transformation to vitamin D. 

Selectivity—The medium should have low selectivity i.e., it should support the growth of a broad spectrum of organisms including fungi and yeasts. 

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