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A psychrotolerant Clostridium species was isolated from vacuum-packed, temperature-abused raw lamb. Colonies of this micro-organism on sheep-blood agar were circular with an entire margin, grey-white, translucent and beta-haemolytic. Cells were single, tapered, motile rods. Elliptical subterminal spores were produced in the late stationary growth phase. Spores did not cause swelling of the maternal cells. The micro-organism was obligately anaerobic. In peptone yeast extract glucose starch (PYGS) broth at pH 7.0, the micro-organism grew optimally between 25.5 and 30.0 degrees C. The temperature range for growth was 2.5-32.2 degrees C. At 26 degrees C, the micro-organism grew optimally at pH 6.8 to 7.0. The pH range for anaerobic growth was 4.7-9.1. The micro-organism was saccharoclastic, hydrolysed starch and degraded xylan. The fermentation products formed in PYGS broth were acetate, formate, lactate, ethanol, butyrate, butanol, hydrogen and carbon dioxide. The G + C content of the DNA was 38.4 mol%. Phylogenetic analyses indicated that the strain belongs to cluster XIVa of the genus Clostridium (sensu Collins et al. 1994). The new strain differed from phylogenetically related clostridia in terms of cellular fatty acid composition, soluble protein profiles and phenotypic properties. On the basis of phenotypic and genotypic characterization data, the strain was assigned to a new species, namely Clostridium algidixylanolyticum. The type strain is strain SPL73T (= DSM 12273T).

Caldocellum saccharolyticum is an extremely thermophilic anaerobic bacterium capable of growth on cellulose and hemicellulose as sole carbon sources. Cellulase and hemicellulase genes have been found clustered together on its genome. The gene for one of the cellulases (celA) was isolated on a lambda genomic library clone, sequenced and found to comprise a large open-reading frame of 5253 base pairs that could be translated into a peptide of 1751 amino acids. To date, it is the largest cellulase gene sequenced. The translated product is a multidomain structure composed of two catalytic domains and two cellulose-binding domains linked by proline-threonine-rich regions (PT linkers). The N-terminal domain of celA encodes for an endoglucanase activity on carboxymethylcellulose, consistent with its high homology to the sequences of several other endo-1, 4-beta-D-glucanases. The carboxyterminal domain shows sequence homology with a cellulase from Clostridium thermocellum (CelS), which is known to act synergistically with a second component to hydrolyze crystalline cellulose. In the absence of a Caldocellum homologue for this second protein, we can detect no activity from this domain.

Summary: Stationary phase cultures of whi2 mutants of Saccharomyces cerevisiae were tested to discover whether they had undergone the changes which wild-type cells show in response to nutrient deprivation. The sensitivity to a 52°C heat shock, nystatin treatment and Zymolyase digestion of the cell wall was determined in isogenic WHI2+ and whi2 strains in both exponential and stationary growth phases. In each case, WH12+ cells become more resistant to these treatments in stationary phase but whi2 cells in stationary phase retained the sensitivity of exponential cultures. In addition, glycogen accumulation was reduced in the whi2 mutant, and DAPI fluorescent staining of the nuclei revealed that nuclear cycle arrest did not occur in G1, but at a minimum of three different phases of the cell cycle. We conclude that under the conditions of deprivation which occur in stationary phase, whi2 mutants retain the properties of exponentially growing cells.