Glycosidases of wheat

Glycosidases isolated from the mill fractions made from soft and hard wheat grists were studied. α-Arabinosidase, α-galactosidase, β-galactosidase, β-glucosidase, β-glucuronidase, β-mannosidase and β-xylosidase activities in wheat flour, germ and bran were determined under standard dough conditions. There were no significant differences between the level of glycosidase activities from hard and soft grists. The level of a particular glycosidase activity was generally highest in the germ and lowest in the flour.     

Presence and Persistence of White Phosphorus On Military Training Ranges

The use of obscurants is a common practice by militaries worldwide. One of the most effective of these is white phosphorus (WP). WP is the elemental form of phosphorus that does not occur in nature and is highly toxic. The use of WP rounds on training ranges has led to a number of die‐offs of grazing land animals and dabbling waterfowl, the first recorded in 1930. In the 1980s, thousands of waterfowl were dying annually at an impact range in Alaska, leading to the first large‐scale investigation of WP as a lethal range contaminant. Tests were conducted at an upland impact range in New York to determine the quantity and persistence of WP in a typical environment. At all sites cited in this paper, WP was persistent for months to years following the detonation of WP munitions. At the Eagle River Flats range in AK, WP was identified from rounds fired in the 1950s, persisting over 45 years in a non‐saturated environment. In New York, dispersal of gram quantities of WP occurred at detonation, and high concentrations of WP were found in the detonation craters a year after firing. Caution needs to be exercised when using white phosphorus munitions on ranges.     

Hydrogen peroxide staining to visualize intracellular bacterial infections of seedling root cells

Visualization of bacteria in living plant cells and tissues is often problematic due to lack of stains that pass through living plant cell membranes and selectively stain bacterial cells. In this article, we report the use of 3,3′‐diaminobenzidine tetrachloride (DAB) to stain hydrogen peroxide associated with bacterial invasion of eukaryotic cells. Tissues were counterstained with aniline blue/lactophenol to stain protein in bacterial cells. Using this staining method to visualize intracellular bacterial (Burkholderia gladioli) colonization of seedling roots of switch grass (Panicum virgatum), we compared bacterial free seedling roots and those inoculated with the bacterium. To further assess application of the technique in multiple species of vascular plants, we examined vascular plants for seedling root colonization by naturally occurring seed‐transmitted bacteria. Colonization by bacteria was only observed to occur within epidermal (including root hairs) and cortical cells of root tissues, suggesting that bacteria may not be penetrating deeply into root tissues. DAB/peroxidase with counter stain aniline blue/lactophenol was effective in penetration of root cells to selectively stain bacteria. Furthermore, this stain combination permitted the visualization of the bacterial lysis process. Before any evidence of H₂O₂ staining, intracellular bacteria were seen to stain blue for protein content with aniline blue/lactophenol. After H₂O₂ staining became evident, bacteria were often swollen, without internal staining by aniline blue/lactophenol; this suggests loss of protein content. This staining method was effective for seedling root tissues; however, it was not effective at staining bacteria in shoot tissues due to poor penetration. Microsc. Res. Tech. 77:566–573, 2014. © 2014 Wiley Periodicals, Inc.     

GROWTH OF SACCHAROMYCES CEREVISIAE AND SACCHAROMYCES UVARUM IN A TEMPERATURE GRADIENT INCUBATOR

A temperature gradient incubator has been used to determine the effect of temperature on the growth of strains of Saccharomyces cerevisiae and Saccharomyces uvarum (including lager brewing yeasts formerly classified as Saccharomyces carlsbergensis). The maximum temperatures for growth (T_max) for all strains of S. cerevisiae examined were in the range 37.5°C-39.8°C and the optimum temperatures for the most rapid initial growth (T_opt) were in the range 30.0°C-35.0°C. Strains of S. uvarum, however, formed two distinct groups: Group A (including all brewing strains of S. uvarum tested) had T_max values 31.6°C-34.0°C and T_opt values 26.8°C-30.4°C; Group B had T_max values 38.2°C-40.0°C and T_opt values 30.0°C-34.6°C. It is proposed, therefore, that the species name S. carlsbergensis should be re-introduced and applied to those strains of S. uvarum (Group A) which have the lower T_max values. Minimum temperatures for growth (T_min) of the yeasts were not investigated as initial studies had shown that they could not be measured satisfactorily. Measurements of the generation times for one brewing strain of S. cerevisiae and one brewing strain of S. uvarum (Group A) over the temperature range 6.0°C-22.0°C have shown that there are significant differences between the yeasts at the lower end of the temperature range and that the relationship between generation time (GT) and temperature (T) for both yeasts closely follows the mathematical expression:      

Role of bacterial association and penetration on destruction of Escherichia coli O157:H7 in beef tissue by high pH

This study was undertaken to determine if association with collagen enables Escherichia coli O157:H7 to resist high-pH treatments and to determine the effects of high pH on the survival of E. coli O157:H7 within different layers of beef tissue. E. coli O157:H7 was inoculated onto purified bovine type I collagen on 12-mm2 circular glass coverslips, plain 12-mm2 circular glass coverslips (control), and 12-mm2 irradiated (cobalt-60) lean beef tissue. The rates of destruction of E. coli O157:H7 inoculated on coverslips in pH 10.5 NaHCO3-NaOH buffer at 35 degrees C were determined at various sampling times. E. coli O157:H7 cells associated with collagen and treated in the same manner were also examined using scanning electron microscopy to determine if association with collagen enabled the organism to resist high-pH treatments. The inoculated tissue was treated in pH 13.0 NaHCO3-NaOH buffer at 25 degrees C, and penetrating cells of E. coli O157:H7 were recovered using a cryostat technique. There was no significant difference (P < 0.05) between the rates of destruction of collagen-associated E. coli O157:H7 and non-collagen-associated E. coli O157:H7 following exposure to high-pH treatments. Scanning electron micrographs showed that collagen-associated E. coli O157:H7 cells appeared physically damaged by exposure to high-pH treatments, and association of E. coli O157:H7 to collagen did not increase the resistance of the organism to destruction by high-pH rinses. No significant differences were seen between 20 ml of NaHCO3-NaOH buffer at pH 13.0 (treatment) and 20 ml of distilled water at pH 7.0 (control) when E. coli O157:H7 cells were recovered in beef tissue at depths of up to 2,000 microm (P < 0.05). The ability of E. coli O157:H7 to penetrate beef tissue may be an important factor in reducing the effectiveness of high-pH treatments in killing this organism on beef tissue. This finding should be considered in the future when designing treatments to decontaminate beef carcasses.