Isolation and typing methods for the epidemiologic investigation of thermotolerant campylobacters

Thermotolerant campylobacters, C. jejuni, C. coli, C. lari and C. upsaliensis, are spiral bacteria involved in human enteric disease. The prevalence of these emerging pathogens, mainly C. jejuni and to a lesser extent C. coli, as etiologic agents of enteric disease in industrialized countries has increased over the last decade. The isolation and culture of these microorganisms is tedious and timeconsuming mainly due to their complex nutritional and environmental requirements. This review discusses the techniques and methods developed for the selective isolation of thermotolerant campylobacters from food, environmental and clinical samples. Additionally, both traditional and newer molecular biology techniques applied to this group of thermophilic organisms for typing and taxonomic purposes are summarized

Putative ancient microorganisms from amber nuggets

Evolutionary microbiology studies based on the isolation of ancient DNA and/or microbial samples are scarce due to the difficulty of finding well preserved biological specimens. However, amber is a fossil resin with natural preserving properties for microbial cells and DNA. The visualization by transmission electron microscopy of different microorganismlike specimens found in amber nuggets from both the Miocene and the Cretaceous periods was accompanied by studies of ancient DNA obtained from the nuggets. After the design of specific primers based on the present sequences of both genes in Saccharomyces cerevisiae, the ancestral AGP2 sequence from the Miocene, as well as the 18S rRNA from the Cretaceous, were amplified. [Int Microbiol 2007; 10(2):117-122

Isolation and taxonomic study of a new canthaxanthin-containing bacterium, Gordonia jacobaea MV-1 sp. nov

This article describes the isolation and taxonomic study of a coryneform isolate of a new Gordonia species (G. jacobaea), strain MV-1, which accumulates several carotenoids, including the ketocarotenoid trans-canthaxanthin. Identification of this new isolate by morphobiochemical methods did not allow unambiguous taxon assignment, but sequencing of the 16S rRNA gene clearly pointed to the genus Gordonia, Gordonia sputi being the closest fit. Differences in certain transversions/ transitions in otherwise very well-conserved sequences of the described Gordonia species supported the proposal of this new taxon. The fact that both the best growth and best pigmentation were obtained with glucose, an inexpensive carbon source and at an industrially suitable temperature, suggests that this new bacterial strain may have good potential for the industrial production of canthaxanthin

A new disruption vector (pDHO) to obtain heterothallic strains from both Saccharomyces cerevisiae and Saccharomyces pastorianus

Yeasts are responsible for several traits in fermented beverages, including wine and beer, and their genetic manipulation is often necessary to improve the quality of the fermentation product. Improvement of wild-type strains of Saccharomyces cerevisiae and Saccharomyces pastorianus is difficult due to their homothallic character and variable ploidy level. Homothallism is determined by the HO gene in S. cerevisiae and the Sc-HO gene in S. pastorianus. In this work, we describe the construction of an HO disruption vector (pDHO) containing an HO disruption cassette and discuss its use in generating heterothallic yeast strains from homothallic Saccharomyces species

Genetic stabilization of Saccharomyces cerevisiae oenological strains by using benomyl

Wild-type oenological strains of Saccharomyces cerevisiae are usually aneuploid and heterozygotes; thus, when they are used as starters in must fermentation the resulting wine characteristics may vary from year to year. Treatment of a wild-type S. cerevisiae oenological strain with benomyl (methyl-l-butylcarbamoyl-2-benzimidazole carbamate), an antifungal agent shown to cause chromosome loss in yeasts, resulted in a stable starter strain in which the parental oenological traits were unchanged. The oenological S. cerevisiae strain was treated with benomyl in two different ways (A and B), and sporulation ability and spore viability were subsequently assayed. Treatment A resulted in both the highest numbers of tetrads and a reduction in DNA cell content, while treatment B increased spore viability. Fermentation assays were carried out with spore clones obtained from treatment A, and the concentrations of glycerol, lactic acid, acetic acid, and ethanol resulting from the treated strains were found to be similar to those of the parental strain. Benomyl treatment thus achieved stable, highly sporulating oenological S. cerevisiae strains of low ploidy, but preserved the desirable oenological properties of the parental strain

Learning from yeasts: intracellular sensing of stress conditions

One intriguing challenge in modern biology is to understand how cells respond to, and distinguish between different stressing stimuli. Evidence accumulated in recent years indicates that a network of signaling pathways extends from the plasma membrane to the very core of the cell nucleus to transduce environmental changes into a graded transcriptional response. Although many steps still remain unclear, studies on the stress-activated protein kinase (SAPK) pathways and related mechanisms provide insight into the biochemistry that regulates signal transmission and leads to outcomes such as cell adaptation and differentiation. This review focuses on selected topics of current interest related to the sensing of stress signals in cells of the fission yeast Schizosaccharomyces pombe. Because signaling pathways appear to be evolutionarily well conserved, yeasts may be useful models to learn how higher eukaryotes sense and respond to stresses at the cellular level

Influence of culture conditions of Gordonia jacobaea MV-26 on canthaxanthin production

Commercial interest in the use of natural pigments isolated from microorganisms has increased in recent years; hence, molecules belonging to the polyisoprenoid group (i.e. β-carotene, astaxanthin, and canthaxanthin) have been the focus of much attention. The bacterium Gordonia jacobaea readily synthesizes and accumulates large amounts of canthaxanthin (β-β´-carotene-4,4´-dione), which is widely used in the food and cosmetics industries. In the present work, the effects of different low-cost raw materials on fermentation and canthaxanthin accumulation by a hyperpigmented strain of G. jacobaea were studied. Canthaxanthin production and peak levels of accumulation varied according to the different media used. [Int Microbiol 2005; 8(1):55-58

Influence of nutritional and environmental factors on ethanol and endopolygalacturonase co-production by Kluyveromyces marxianus CCEBI 2011

Ethanol and endopolygalacturonase (endoPG) are simultaneously produced by the yeast Kluyveromyces marxianusCCEBI 2011. The aim of this study was to determine the optimal combination of seven environmental and nutritional variables, as well as the influence of each one, with respect to the fermentation process in yeast cultures in which sugarcanejuice was the substrate. Simplex sequential optimization showed that after 15 runs the optimal conditions were: pH, 4.6; temperature, 31ºC; total reducing sugars (TRS), 125 g/l; (NH4)2SO4, 2.48 g/l; (NH4)2HPO4, 2.73 g/l; CaCl2, 0.33 g/l andMgSO4·7H2O, 0.54 g/l. Under these conditions, the ethanol concentration was 47.6 g/l and endoPG concentration was 9.8 U/ml, which represented increases of 22% and 10%, respectively, over the concentrations obtained under suboptimal conditions. Temperature and (NH4)2SO4 supplementation were the most significant factors influencing the co-production process. [Int Microbiol 2011; 14(1):41-49