"This is the highly anticipated third edition of a book written by the Working Party on Culture Media of the International Committee on Food Microbiology and Hygiene. It is a handy reference for microbiologists wanting to know which media to use for the detection of various groups of microbes in foods and how to check the performance of the media. | The book is divided into two parts and concentrates on media for water as well as food microbes - selecting those which have been evaluated and shown to function optimally. The first part consists of a series of chapters written by various experts from all over the world, reviewing the media designed to detect the major groups of microbes important in food spoilage, food fermentations and food-borne disease. The history and rationale of the selective agents and indicator systems used, as well as the relative merits of the various media are surveyed by reference to the scientific literature. The second part contains monographs on almost 100 of the media considered most useful. Each monograph, written in the style of a pharmacopoeia, includes: a short section on the history and selective principle of the medium; a method for its preparation from basic ingredients; its appearance and physical properties, including pH; its shelf-life; instructions concerning method of inoculation, incubation and interpretation; the recommended method(s) and a list of test strains suitable for assessing the quality (productivity and selectivity) of the medium and a description of the typical appearance of the target organism"--Publisher decription.

Campylobacter spp. is a major source of global gastrointestinal infections. Their enteric infections are linked to the consumption of undercooked poultry products, contaminated milk and water, and the handling of wild animals and birds. The detection of Campylobacter spp. in water and food samples mainly depends on culture-based techniques. Public Health England (PHE), the U.S. Food and Drug Administration (FDA), and the International Standard Organization (ISO) have standardized Campylobacter spp. isolation and enumeration procedures for food and water samples, which involve the usage of selective agar media and enrichment broth. Different types of selective plating and enrichment media have been prepared for Campylobacter spp. detection and assessment during regular food surveillance and food poisoning. To date, culture media remains the standard option for microbiological food analysis and has been approved by the U.S. Environmental Protection Agency (US EPA), Food and Agriculture Organization (FAO), and World Health Organization (WHO). This review discusses the standard microbiological protocols for Campylobacter spp. isolation and enumeration in food and water and evaluates detection media (pre-enrichment, selective enrichment, and selective plating) for their rational applications. Moreover, it also elaborates on the advantages and disadvantages of recent chromogenic culture media in Campylobacter spp.-oriented food surveillance. This review also highlights the challenges of culture-based techniques, future developments, and alternative methods for Campylobacter spp. detection in food and water samples.

The work is intended to explore the suitability of underutilized coconut water (a byproduct of food industry) for the production of exopolysaccharides (EPS) by Agrobacterium sp. CFR 24. Besides checking the suitability of coconut water for the production of water-soluble (WS) and water-insoluble (WIS) EPS, certain fermentation parameters, such as initial pH, incubation period and kinetics of EPS production were investigated. The coconut water medium was found to support the production of both types of EPS. The optimal initial pH and temperature was found to be 6·0 and 30°C, respectively. In shake flask (150 rev min[superscript [-]1]) studies, high-cell density inoculum resulted in the production of 11·50 g l[superscript [-]1] of WIS-EPS and 4·01 g l[superscript [-]1] WS-EPS after 72 and 96 h of fermentation, respectively. Coconut water was found suitable for the production of microbial EPS by Agrobacterium sp. CFR 24 strain. Under optimum conditions, it produced a good amount of WIS-EPS, which is comparable with that of the sucrose medium (11 g l[superscript [-]1]). This is the first report on the use of coconut water as a fermentation medium for the production of any microbial EPS. Besides producing value-added products, use of this food industry byproduct, which is often being drained out, can significantly reduce the problem of environmental pollution.

: The influence of temperature (T) and water activity (a w) on the growth rate (μ) of seven moulds (Alternaria alternata, Aspergillus flavus, Cladosporium cladosporioides, Mucor racemosus, Penicillium chrysogenum, Rhizopus oryzae and Trichoderma harzianum) was assessed in suboptimal conditions. Firstly, the dependence of fungal growth on temperature, at a w 0.99, was modelled through an approach described previously for bacteria. A dimensionless growth rate variable: μ dᵢₘα=μ/μ ₒₚₜα depended on the following normalised temperature: T dᵢₘ=(T−T ₘᵢₙ)/(T ₒₚₜ− T ₘᵢₙ) according to a power function: μ dᵢₘα=[T dᵢₘ] ᵅ , where α was an exponent to be estimated. Secondly, the same approach was used to describe the influence of a w on fungal growth, at the respective optimum temperatures for each mould. Similarly, μ dᵢₘᵦ=μ/μ ₒₚₜᵦ depended on the following normalised water activity: a wdᵢₘ=(a w−a wₘᵢₙ)/(a wₒₚₜ−a wₘᵢₙ) according to a power function: μ dᵢₘᵦ=[a wdᵢₘ]ᵝ. Results show: (i) for each mould, the α-value is significantly less than the β-value, confirming that water activity has a greater influence than temperature on fungal development; (ii) the α-values and the β-values depend on the mould; (iii) the α-value is less than 1 for the mesophilic mould A. flavus, whereas the other moulds are characterised by higher α-values ranging from 1.10 to 1.54; (iv) the mesophilic A. flavus exhibits a low β-value, 1.50, compared to the hydrophilic T. harzianum, β=2.44, while β-values are within the range (1.71–2.37) for the other moulds. Journal of Industrial Microbiology & Biotechnology (2002) 28, 311–315 DOI: 10.1038/sj/jim/7000248

Aeromonas hydrophila, a ubiquitous inhabitant of aquatic environments, commonly expresses several cell-surface properties that may contribute to virulence. Since many aquatic microorganisms in hostile environments can withstand starvation conditions for long periods, we examined the effect of storage under nutrient poor conditions on the expression of cell-surface properties of this pathogen. Phenotypes studied were: (1) cell surface hydrophobicity and charge, and (2) the ability to bind connective-tissue proteins and lactoferrin. Our results suggest that the response of A. hydrophila to nutrient-poor conditions is regimen specific. Generally, A. hydrophila cells became more hydrophobic and significantly increased their ability to bind the iron-binding glycoprotein lactoferrin when the bacterium was stored under nutrient-poor conditions; however, under these conditions, the cells seemed to lose their ability to bind connective tissue proteins.

Methods are presented for investigating the site and form of growth of bacteria in model oil-in-water emulsions and in dairy cream. Following growth of the bacteria, the continuous aqueous phase is gelled using agarose and the oil phase removed using a mixture of chloroform and methanol. Using this method, the authors have found that Listeria monocytogenes, Salmonella typhimurium and Yersinia enterocolitica grow in the form of colonies in concentrated oil-in-water emulsions. Colonies of L. monocytogenes and Y. enterocolitica also form in artificially-inoculated fresh and tinned dairy cream. If information about the precise site of growth is not required, the authors have discovered that intact colonies can be liberated from the model emulsions by dissolving away the oil phase with chloroform: methanol.

The antimicrobial effect of water extracts of sumac (Rhus coriaria L.) at concentrations of 0.1%, 0.5%, 1.0%, 2.5% and 5.0% (w/v), non-neutralized and after neutralization to pH 7.2 +/- 0.1, was studied on the growth of 12 bacterial strains (six Gram positive strains and six Gram negative strains), mostly food borne including pathogens. It was found to be effective against all the test organisms with Gram positive strains being more sensitive than Gram negative strains. Significant differences (P<0.01) were found among the bacteria and between the non-neutralized and neutralized extracts with non-neutralized being more effective against all the bacteria. The minimal inhibitory concentration (MIC) of the extract for each bacterial strain was studied by a gradient plate method. Among the Gram positive organisms, Bacillus species (Bacillus cereus, Bacillus megaterium, Bacillus subtilis, and Bacillus thuringiensis) were found to be the most sensitive showing MICs of 0.25-0.32% (after 24 h incubation) followed by Staphylococcus aureus (0.49%), while Listeria monocytogenes was found to be the least sensitive demonstrating a MIC of 0.67%. Of the Gram negative organisms, Salmonella enteritidis was found to be the most resistant with a MIC of 0.67% followed by Escherichia coli Type I, E. coli O157:H7, Proteus vulgaris and Hafnia alvei having MICs of 0.63%, 0.60%, 0.55% and 0.45%, respectively; whereas Citrobacter freundii was found to be the least resistant surviving up to 0.42%. Some loss of antimicrobial activity was, however, observed after incubation for 3 days. Bacteriostatic/bactericidal effects of sumac, as studied by enumerating survival by the viable count technique after 1 h direct contact of each microorganism with various concentrations of sumac extract, revealed a 4-5 log cycle reduction in Bacillus spp. and 2-3 log cycle reduction in other bacteria tested with 1.0% sumac extract.

A polymerase chain reaction (PCR) assay with two nested pairs of primers selected from conserved sequences within a 2.3 kb randomly cloned DNA fragment from the Salmonella typhimurium chromosome was developed. The nested PCR assay correctly identified 128 of a total of 129 Salmonella strains belonging to subspecies I, II, IIIb and IV. One strain of Salm. arizona (ssp. IIIa) tested negative. No PCR products were obtained from any of the 31 non-Salmonella strains examined. The sensitivity of the assay was 2 cfu, as determined by analysis of proteinase K-treated boiled lysates of Salm. typhimurium. The performance of the assay was evaluated for environmental water, sewage and food samples spiked with Salm. typhimurium. Water and sewage samples were filtered and filters were enriched overnight in a non-selective medium. Prior to PCR, the broth cultures were subjected to a rapid and simple preparation procedure consisting of centrifugation, proteinase K treatment and boiling. This assay enabled detection of 10 cfu 100 ml(-1) water with background levels of up to 8700 heterotrophic organisms ml(-1) and 10000 cfu of coliform organisms 100 ml(-1) water. Spiked food samples were analysed with and without overnight enrichment in a non-selective medium using the same assay as above. Nested PCR performed on enriched broths enabled detection of < 10 cfu g(-1) food. Variable results were obtained for food samples examined without prior enrichment and most results were negative. This rapid and simple assay provides a sensitive and specific means of screening drinking water or environmental water samples, as well as food samples, for the presence of Salmonella spp.