实验基础

This chapter discusses the findings of many studies in food, clinical and environmental microbiology including approaches that have been used to overcome inhibition and facilitate amplification for detection and typing.

The chemical and physical environment of grape juice during fermentation, coupled with competition from indigenous yeast and bacteria, can present significant challenges to the growth of Saccharomyces cerevisiae. Individually or collectively, these factors may impact both y ...

Lactic acid bacteria (LAB) have been received much attention as bacteriocin producers. Antimicrobial proteins and peptides produced by bacteria, termed bacteriocin, are widely acknowledged to be important contributors to those organisms that survive dominate or die in microbi ...

Yeasts have been associated with foods since earliest times, both as beneficial agents and as major causes of spoilage and economic loss. Current losses to the food industry caused by yeast spoilage are estimated at several million pounds annually in the UK alone. As new food ingredients and new fo ...

Multilocus enzyme electrophoresis (MEE) is a method for characterizing organisms by the relative mobilities under electrophoresis of a large number of intracellular enzymes. These differences in mobility are directly related to mutations at the gene locus that cause amino acid sub ...

Strains tolerant to high temperatures, ethanol levels, and high concentrations of sugar are highly desirable for a fermentation process. The maintenance of a high degree of viability during the operation of a process, biomass storage, and pauses between batches is fundamental. Ferment ...

Flocculation is a naturally occurring process of reversible aggregation (cell-cell aggregation) of yeast cells (1), whereas flotation is defined as microbial enrichment in foams (2), which can be carried out either by induced flotation (with addition of flotation agents) or spontane ...

Microorganisms have been used intensively by the food industry as well as by pharmaceutical and other chemical industries. A great number of global companies take advantage of fermentation processes in the manufacture of a spectrum of useful products. Many of these processes involve yea ...

Chapter 38 deals with methods for hybridization of yeasts in different genera by protoplast fusion and for selection of hybrids by double-fluorescence staining and use of a micromanipulator. This chapter describes a similar but automated and rapid procedure for selection of hybrids; f ...

The characterization of yeasts at the strain level is of relevance from an industrial point of view because numerous yeast strains belong to the natural flora of commercial fermented foods and beverages (bakery products, cheeses, cold meats, wines, and beers) and take part in fermentation pr ...

There is great commercial interest in using immobilization technology for fermentation processes. Microbial immobilization is one of the novel methods in fermentation technology, especially important in the food and beverage industry, which allows the use of increased cell con ...

Cassava (Manihot esculenta) is a root crop of tropical American origin and is the fourth most important staple crop in the tropics. In the developing world, it is surpassed only by maize, rice, and sugarcane as a source of calories; cassava’s starchy roots produce more food energy per unit of land than any o ...

Isolation and enumeration of the microorganisms present in foods usually demands preliminary treatment of samples to release into a liquid medium those microorganisms present that may be included within the food. In a mixing procedure known as “stomaching,” the food sample (see Note 1) and d ...

The final product of spontaneous grape must fermentation (natural fermentation) is the result of the combined action of different yeast species and vine varieties. Both of them contribute, in different ways, to the organoleptic properties of wine (1). At the first fermentation stages, lem ...

The coliform group of indicator organisms includes some members of this family that are capable of fermenting lactose with the production of acid and gas within 48 h at 35�C. The family Enterobacteriaceae are Gram-negative oxigenic and facultatively anoxigenic rods, nonspore forming, t ...

The Formol titration is a simple and rapid method for determination of the quantity of assimilable nitrogen in juice (1). It provides an approximate, but useful, index of must nutritional status. The procedure consists of neutralizing a juice sample with base to a given pH, adding an excess of neutra ...

The conversion of grape juice into wine is a complex fermentation process in which yeasts play a central role. The composition of the yeast flora in the fermenting must vary according to geographic location, climatic conditions, and grape variety (e.g., ref. 1). During the early phase of fermentat ...

Yeast and molds (nonfilament and filament molds) may be found as part of the normal flora of a food product on inadequately sanitized equipment or as airborne contaminants. They can produce toxic metabolites, resistance to freezing environments, and cause off odors and off flavors of foods. Me ...

Carotenoid production or occurrence—including derivatives biosynthesized from precursors—is widespread in nature in both the Prokaryota and Eucaryota superkingdoms and more than 600 different chemical structures are reported (1), most of them as tetraterpenoids (C40). Ma ...

The mesophilic microorganism is ones of the more general and extensively microbiological indicators of food quality, (1) indicating the adequacy of temperature and sanitation control during processing, transport, and storage, and revealing sources of contamination during ma ...