Effects of culture conditions on the size, morphology and wet density of spores ofBacillus cereus569 andBacillus megateriumQM B1551

Abstract

Significance and Impact of the Study: 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. As a result, they are of concern in the food processing, healthcare and other sectors, and are of increasing biotechnological interest. Improved understanding of variance in spore size, morphology and density may aid the development of certain spore-associated applications (e.g. spore surface display) while contributing to active areas of research such as spore adhesion and resistance to heat. AbstractThe influence of variable culture conditions on the size and wet density of spores of Bacillus cereus and Bacillus megaterium were examined in this work. 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. 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%. Similarly, as the spore elongated to yield aspect ratios larger than 1Á4, their shape changed from typical prolate spheroids to cylinders with hemispherical ends. 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.

Paramagnetism in Bacillus spores: Opportunities for novel biotechnological applications

“…This may be a result of the large exosporium present in B. cereus spores, which may provide a greater number of sites for the adsorption of manganese ions. The average exosporium surface area of B. cereus spores is approximately 25% larger than that of B. megaterium spores (Xu Zhou, Wisnivesky, Wilson, & Christie, ).…”

Proteins Encoded by the gerP Operon Are Localized to the Inner Coat in Bacillus cereus Spores and Are Dependent on GerPA and SafA for Assembly

“…Competent Escherichia coli DH5␣ cells (NEB UK) were used for cloning procedures and for the propagation of plasmids. Bacillus cereus spores were prepared by nutrient exhaustion in casein-hydrolysate yeast-extract (CCY) liquid medium (24). Efficient sporulation was achieved using 200-ml cultures in 2-liter baffled flasks that were subject to orbital agitation at 30°C for 48 h. The resultant spores were purified from cellular debris by centrifuging and resuspending the spore pellets initially in phosphate-buffered saline (PBS) supplemented with 0.1% (wt/vol) Tween 20, followed by several rounds of washing and resuspending spores in ice-cold deionized water.…”

Microbial metabolomics: essential definitions and the importance of cultivation conditions for utilizing Bacillus species as bionematicides

“…; Xu Zhou et al . ). Maximum protease production for both B. subtilis and B. licheniformis was reached at 40°C with an optimum pH of 6·0–6·5 (Ray et al .…”

“…A number of studies have investigated the influence of cultivation conditions on Bacillus spore production (Posada-Uribe et al 2015;Xu Zhou et al 2017), while others focused on conditions for optimum protease production (Ray et al 2012;Sarker et al 2013). It was found that alkaline media and elevated temperatures reduced the volume of spores, while aeration and agitation rates affected spore cell density (Posada-Uribe et al 2015;Xu Zhou et al 2017). Maximum protease production for both B. subtilis and B. licheniformis was reached at 40°C with an optimum pH of 6Á0-6Á5 (Ray et al 2012).…”