Calcium-barium and calcium-strontium spores germinated readily. Significant differences existed in the rates of germination calcium spores germinated fastest, strontium spores were slower, and barium spores were slowest. Strontium and barium spores were heat-resistant however, calcium was essential for maximal heat resistance. Viability of the barium spores was considerably less than that of the other two types. From binary equimolar mixtures of the metal salts, endotrophic spores accumulated both metals to nearly the same extent. The calcium content of the strontium and the barium spores was very small. Analyses revealed that the different spore types were enriched specifically in the metal to which they were exposed during sporogenesis. Thin-section electron micrographs revealed no apparent anatomical differences among the three types of spores. Normal, refractile spores were produced in each case a portion of the barium spores lost refractility and darkened. 1966.— Spores were produced by washed vegetative cells suspended in deionized water supplemented with CaCl2, SrCl2, or BaCl2. Endotrophic calcium, strontium, and barium spores of Bacillus megaterium and Bacillus cereus. (The University of Texas, Austin), and J. Letters in Applied Microbiology published by John Wiley & Sons Ltd on behalf of Society for Applied Microbiology.Įndotrophic Calcium, Strontium, and Barium Spores of Bacillus megaterium and Bacillus cereus1įoerster, Harold F. spore surface display) while contributing to active areas of research such as spore adhesion and resistance to heat. Improved understanding of variance in spore size, morphology and density may aid the development of certain spore-associated applications (e.g. As a result, they are of concern in the food processing, healthcare and other sectors, and are of increasing biotechnological interest. Bacterial spores of the genera Bacillus and Clostridium represent nature's most durable cells in terms of their extreme resistance to a variety of deleterious environments. In contrast with previous studies, culture conditions employed in this study exerted no discernible impact on the wet density of B. cereus or B. megaterium spores. Similarly, as the spore elongated to yield aspect ratios larger than 1Â♴, their shape changed from typical prolate spheroids to cylinders with hemispherical ends. Increasing concentrations of inorganic salts in sporulation media exerted differing effects on each species whereas a fivefold increase in the concentration of all salts resulted in only minor differences to the dimensions of B. cereus spores, B. megaterium spores became more elongated, displaying an average increase in volume of almost 30%. Culture temperature and initial pH was shown to have a significant impact on the size of both species, with increasingly alkaline culture media and elevated culture temperatures resulting in spores that were, on average, up to 25% reduced in volume. The influence of variable culture conditions on the size and wet density of spores of Bacillus cereus and Bacillus megaterium were examined in this work. Xu Zhou, K Wisnivesky, F Wilson, D I Christie, G Effects of culture conditions on the size, morphology and wet density of spores of Bacillus cereus 569 and Bacillus megaterium QM B1551.
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