Occurrence of Potentially Pathogenic Bacteria in Epilithic Biofilm Forming Bacteria isolated from Porter Brook River-stones,Sheffield, UK

Biofilms in aquatic ecosystems develop on wet benthic surfaces and are primarily comprised of various allochthonous microorganisms, including bacteria embedded within a self-produced matrix of extracellular polymeric substances (EPS). In such environment, where there is a continuous flow of water, attachment of microbes to surfaces prevents cells being washed out of a suitable habitat with the added benefits of the water flow and the surface itself providing nutrients for growth of attached cells. When watercourses are contaminated with pathogenic bacteria, these can become incorporated into biofilms. This study aimed to isolate and identify the bacterial species within biofilms retrieved from river-stones found in the Porter Brook, Sheffield based on morphological, biochemical characteristics and molecular characteristics, such as 16S rDNA sequence phylogeny analysis. Twenty-two bacterial species were identified. Among these were 10 gram-negative pathogenic bacteria, establishing that potential human pathogens were present within the biofilms. Klebsiella pneumoniae MBB9 isolate showed the greatest ability to form a biofilm using a microtiter plate-based crystal violet assay. Biofilm by K. pneumoniae MBB9 formed rapidly (within 6 h) under static conditions at 37 °C and then increased up to 24 h of incubation before decreasing with further incubation (48 h), whereas the applied shear forces (horizontal orbital shaker; diameter of 25 mm at 150 rpm) had no effect on K. pneumoniae MBB9 biofilm formation.     

Effects of ionizing radiation on the growth and allyl isothiocyanate accumulation of Wasabia japonica in vitro and ex vitro

Mutations were induced in tissue-cultured wasabi (Wasabia japonica Matsumura) by treating in vitro-derived shoot tips with either γ-rays or X-rays at 0, 10, 20, 40 or 80 Gy. Doses of up to 40 Gy of either γ- or X-ray treatments resulted in a survival rate of more than 60% in culture after 3 mo. The use of γ- or X-rays at doses between 10 Gy and 40 Gy to induce mutation in W. japonica resulted in an alteration of the growth and allyl isothiocyanate (AITC) content of multiple shoots after 3 mo. in culture on Murashige and Skoog medium containing 5 μM N⁶-benzyladenine (BA). Putative mutants from the 40 Gy treatments of either γ- or X-rays exhibited a reduction in shoot weight, number, and height, whereas treatments of either γ-rays or X-rays at 10 Gy and 20 Gy doses showed no significant differences in shoot growth. All shoots treated with 80 Gy were either necrotic or irregenerable, while those treated with 40 Gy produced deformed leaves, from both types of ionizing radiation. Concentrations of AITC were measured by the use of gas chromatography-mass spectrometry (GC-MS). The accumulation of AITC was shown to decrease when doses increased in both γ- and X-ray treatments, compared with the controls. Positive responses were solely occurred at 18 mo. after transfer of in vitro rooted shoots to the shade house. The survival rate, rhizome weight and AITC content of plants derived from shoots treated with 20 Gy or 40 Gy of either γ-rays or X-rays were significantly greater than those of the controls.     

Protoplast formation and regeneration in <Emphasis Type="Italic">Lactobacillus delbrueckii</Emphasis>

Method for production and regeneration of Lactobacillus delbrueckii protoplasts are described. The protoplasts were obtained by treatment with a mixture of lysozyme and mutanolysin in protoplast buffer at pH 6.5 with different osmotic stabilizers. The protoplasts were regenerated on deMan, Rogosa and Sharpe (MRS) with various osmotic stabilizers. Maximum protoplast formation was obtained in protoplast buffer with sucrose as an osmotic stabilizer using a combination of lysozyme (1 mg/ml) and mutanolysin (10 μg/ml). Maximum protoplast regeneration was obtained on MRS medium with sucrose (0.5 M) as an osmotic stabilizer. The regeneration medium was also applicable to other species of lactobacilli as well. This is, to our knowledge, the first report on protoplast formation and efficient regeneration in case of L. delbrueckii.     

Relations between elevated temperatures and fermentation behaviour of Kloeckera apiculata and Saccharomyces cerevisiae associated with winemaking in mixed cultures

One of the important factors affecting wine fermentation is temperature. The influence of elevated temperatures from 10 to 25 °C at 5 °C intervals on yeast growth and fermentation products were studied in mixed cultures of Kloeckera apiculata and Saccharomyces cerevisiae in grape juice. In the experiments carried out at 10 and 15 °C, K. apiculata grew and survived longer compared to trials conducted above 20 °C. In most cases, higher temperatures stimulated the production of higher alcohols but lowered the formation of esters and acetaldehyde. This revised version was published online in July 2006 with corrections to the Cover Date.     

Chroococcopsis epiphytica n. sp., eine neue Cyanophycee aus dem Gebiet des Neusiedler Sees

The morphology and life history ofChroococcopsis epiphytica nova spec. is described, a German and Latin diagnosis is added. Cultivated plants display some differences in comparison with plants in their natural habitat: calcification occurs only in the natural medium, endosporangia are developed only by cultivated plants. At the basis, where single cells and thalli are attached, a special sort of jelly is produced; it is discernible only by elective staining with methylene blue. The systematic position of the new species is discussed.

     

Effects of additional illumination and fertilization on seasonal changes in fine-scale grassland community structure

Abstract. Fine-scale structure of a species-rich grassland was examined for seasonal changes caused by manipulated changes in the availability of above and below-ground resources (additional illumination with the help of mirrors and fertilization) in a field experiment. If changes induced by fertilization — which are expected to lead to a reduction in small-scale diversity —are due to intensified light competition, they should be compensated for by additional light input. Permanent plots of 40 cm × 40 cm were sampled by the point quadrat method at three angles (60°, 90° and 120° from the horizontal North-South direction), using a laser beam to position the quadrats, in early July and early September. The applied treatments did not cause apparent changes in plant leaf orientation. The degree of spatial aggregation of biomass increased seasonally in fertilized, non-illuminated plots: greater productivity at a constant light supply led to a faster growth rate of potentially dominant species, as compared to the subordinate ones. Additional illumination mitigated this effect of fertilization, indicating that the observed changes in biomass aggregation were due to increased light competition. There was a considerable seasonal decrease of variance ratio (ratio of observed variance of richness at a point and variance expected at random) in fertilized only and in illuminated only plots. In fertilized plots this was due to the positive relationship between biomass aggregation and expected variance of richness. Biomass constancy occurs to be inversely related to deficit in variance of richness. In illuminated plots, in contrast, only the observed variance of richness decreased seasonally, indicating a more uniform use of space by different species. Evidently, a deficit in variance of richness can be caused by drastically different processes, showing that the variance ratio statistic may not have a significant explanatory value in fine-scale community studies.