Other Microorganisms

Under conditions of low oxygen as would occur in barreled wine, Acetobacter will produce acetaldehyde rather than acetic acid (Drysdale and Fleet, 1989b). As an explanation, the authors speculated that while the alcohol dehydrogenase is active under low oxygen, the activity of acetaldehyde dehydrogenase could be impeded (Fig. 3.3). Besides the sensory 

Besides acetic acid and acetaldehyde, Acetobacter also produces ethyl acetate. This pungent ester contributes to the sensory interpretation of volatile acidity (Section 11.3.1). However, synthesis is affected by available oxygen resulting in less ethyl acetate being produced under low oxygen conditions (Drysdale and Fleet, 1989b). 

As an example, Aspergillus produces asexual spores (conidiospores or conidia) on a structure called an aspergillum, which consists of a swollen 

Molds are capable of growth on the outer and inner surfaces of wooden storage containers and on cork in bottled wines where seepage has occurred. Aside from esthetic problems of growth on these surfaces, molds produce sensorially powerful metabolites that are perceivable at parts-per-billion or parts-per-trillion concentrations. As such, these compounds can play a significant role in wine quality (Section 4.5.3). 

Where warm, sunny, and windy weather follows the primary infection by Botrytis, free water in the cluster evaporates, and the fruit begins a process of dehydration, yielding the so-called noble rot (Doneche, 1993). Although mold and bacterial growth continues to consume a portion of the sugars and acids, this is countered by a concentration of flavors and 

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Antibiotics are toxic water-solubie compounds produced by molds or bacteria which inhibit the growth of other microorganisms. For an antibiotic to be useful in medicine it should have a high order of selective toxicity to microorganisms which are pathogenic to man. Al-... 

Peptide Antibacterials and Antifungals from Other Microorganisms... 

The yeast must be so finely dispersed throughout the wort that a quick yeast growth is assured, which leaves no possibiUty for other microorganisms, if any, to develop. The inoculation of yeast occurs through injection directly into the wort pipe. To be used in the next batch of wort, the yeast that is harvested after the end of fermentation must be protected against contamination. 

Germicidal Properties. The germicidal activity of aqueous chlorine is attributed primarily to HOCl. Although the detailed mechanism by which HOCl kills bacteria and other microorganisms has not been estabUshed, sufficient experimental evidence has been obtained to suggest strongly that the mode of action involves penetration of the cell wall followed by reaction with the enzymatic system. The efficiency of destmction is affected by temperature, time of contact, pH, and type and concentration of organisms (177). 

Sporicide kills (inactivates) bacterial spores, and is therefore expected to kill all other microorganisms of less resistance. According to the AO AC International it may not kill 100% of the spores, and therefore may not be as powerful as a sterilant. However, according to the EPA, sporicide and sterilant are considered identical. 

A.ntibiotic is an organic chemical substance produced by microorganisms that has the capacity in low concentration to selectively destroy or inhibit the growth of other microorganisms without injuring the host cells. It may be adrninistered systemicaHy and be an antimicrobial chemotherapeutic agent. 

Process Description Microfiltration (MF) separates particles from true solutions, be they liquid or gas phase. Alone among the membrane processes, microfiltration may be accomplished without the use of a membrane. The usual materi s retained by a microfiltra-tion membrane range in size from several [Lm down to 0.2 [Lm. At the low end of this spectrum, very large soluble macromolecules are retained by a microfilter. Bacteria and other microorganisms are a particularly important class of particles retained by MF membranes. Among membrane processes, dead-end filtration is uniquely common to MF, but cross-flow configurations are often used. 

Commercial Alcoholic beverages Sauerkraut Pickles Cheeses Lactic acid Various yeasts, molds, and bacteria L. plantatum plus other bacteria L. plantaixim plus other bacteria Propionibacteria, molds, and possibly many other microorganisms Two lactobacillus species... 

There have been only a few studies have evaluated membrane microfiltration of secondary wastewater effluent. Microfiltration membranes might be used to achieve very low turbidy effluents with very little variance in treated water quality. Because bacteria and many other microorganisms are also removed, such membrane disinfection might avoid the need for chlorine and subsequent dechlorination. Metal... 

Other Microorganisms. There are several other microorganisms that affect the corrosion of metal directly or indirectly. Some examples are yeasts and molds, algae and protozoa. For the present purposes it is sufficient to realize that there are other micro-... 

A possible example of this thesis is the crystalline insect toxin found in Bacillus thuringiensis spores and discussed here by Dr. Anderson. Although neither the bacillus nor its spores exhibit useful antibiotic activity against other microorganisms, the very specific toxicity to insects has become of major commercial interest. The enormous number and variety of fungal species available for further examination must lead inevitably to one or more which produces pesticidal metabolites. 

Nitrite formulations are employed for both hot and cold water closed loops (and also occasionally for open cooling systems). Unfortunately, nitrite is easily oxidized to nitrate and is very susceptible to microbiological attack (by Nitrobacter agilis and other microorganisms). Nevertheless, it is a good low-cost passivating inhibitor. 

Illustrative examples of biotransformation reactions include the following, although it should be emphasized that other microorganisms may be able to degrade the substrates ... 

It is worth drawing attention to the significance of other issues. In natural ecosystans, other microorganisms including bacteria are almost always present and it has been shown that, in experiments using [7,10- C]benzo[a]pyrene, incubation for 215 d mth Bjerkandera sp. strain BOS55 alone resulted in the formation of 13.5% C02 and 61% of labeled metabolites in the... 

It was obvious from Pasteur s studies that each special kind of fermentation or disease of beer or wine was the result of the growth and activity in it of a special, distinct form of yeast or other microorganism, depending on the type of fermentation or disease under investigation. This furthered an idea, already old, of the specificity of biological action, and supported the view that animal and human diseases also, like different sorts of putrefaction and fermentation, were each caused by a single, specific type of microorganism. 

Figure 11.1 Representative secondary metabolites produced by Streptomyces ceolicolor and other microorganisms, including aromatic polyketides actinorhodin and tetrohydroxynaphthalene (a), side-rophore desferrioxamines (b), polyunsaturated fatty acid eicosapentaenoic acid (c) and terpenoids beta-...

Even if, as discussed above, DFO can enhance the growth of selected microorganisms that have the capacity to extract the iron from FO, the drug may, by withdrawing iron, limit the growth of many other microorganisms (Boelaert et ah, 1993b). Whether this may have clinical application in the prevention or cure of some infectious diseases will be discussed later in this chapter. 

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