Electron Microscopic Examination of the Dormant Spore and the Sporulation of Paenibacillus motobuensis Strain MC10

Abstract

Spore-forming bacteria are generally stained Grampositively. However, spore-forming bacteria isolated from air and soil are often stained Gram-negatively. MC10 strain of Paenibacillus motobuensis is a newly isolated strain from soil compost in Okinawa, but is stained Gram-negatively though it produces definite endospores (8). This bacterium has a cell wall structure characteristic of ordinary Gram-positive bacteria according to electron microscopic examination (8). At present the mechanisms of Gram-negative stainability of this bacteria is not elucidated and we need more precise examination of the bacterial cell wall to elucidate it. Meanwhile, the morphological characteristics of the spore of this Gram-negative, spore-forming bacterium is also an interesting question. Thus in this report we examined by electron microscopy the structure of the spore and sporulation processes of this bacterium in order to learn whether the spore of this bacterium has a different structure or sporulation process from that of ordinary Gram-positive spore forming bacteria (7, 12). Materials and MethodsBacterial strains. Strain MC10 of Paenibacillus motobuensis (8) and W23 of Bacillus subtilis (3) were used. These strains were cultured on Luria agar plates (L-plate) at 37 C. The dormant spores of these strains were harvested from L-plates after 3 days of culture at 37 C. To examine an early stage of sporulation, the bacteria were harvested after 24 hr of culture.Electron microscopy: thin sectioning technique. For electron microscopic examination, the spore of MC10 strain was collected from the L-plate by scraping the colonies with a wire loop, suspended in phosphate Abstract: We previously reported a new species Paenibacillus motobuensis. The type strain MC10 was stained Gram-negative, but had a Gram-positive cell wall structure and its spore had a characteristic star shape. The spore and sporulation process of P. motobuensis strain MC10 were examined by electron microscopy using the technique of freeze-substitution in thin sectioning. The structure of the dormant spore was basically the same as that of the other Bacillus spp. The core of the spore was enveloped with two main spore components, the cortex and the spore coat. In thin section, the spore showed a star-shaped image, which was derived from the structure of the spore coat, which is composed of three layers, namely the inner, middle and outer spore coat. The middle coat was an electron-dense thick layer and had a characteristic ridge. By scanning electron microscopic observation, the ridges were seen running parallel to the long axis of the oval-shaped spore. The process of sporulation was essentially the same as that of the other Bacillus spp. The forespore was engulfed by the mother cell membrane, then the spore coat and the cortex were accumulated in the space between the mother cell membrane and forespore membrane. The mother cell membrane seemed to participate in the synthesis of the spore coat. MC10 strain showed almost identical heat resistance to that of B. subtilis.

Data on the ultrastructural characteristics of Paenibacillus polymyxa isolates and biocontrol efficacy of P. polymyxa ShX301

“…Sporulation process of Paenibacillus polymyxa strain ShX301 was described [1] , which was similar to that described in P. motobuensis by Iida et al [2] . While other four strains (Hb1, Hb6, ShX302 and ShX303) of P. polymyxa also shared the same characteristics with strain ShX301.…”

Preparation, characteristics and cytotoxicity of green synthesized selenium nanoparticles using Paenibacillus motobuensis LY5201 isolated from the local specialty food of longevity area

“…1b, 16S rRNA gene sequence and phylogenetic evolution analysis showed that LY5201 have a high degree of similarity (92%) with Paenibacillus motobuensis NR 043153.1. It also exhibited the typical biochemical characteristics of P. motobuensis [22] as indicated in Table S1 (supporting data). The strain LY5201 was identi ed as P. motobuensis LY5210.…”

Evaluation of Peroxides and Chlorine Oxides as Disinfectants for Chemical Sterilization of Gnotobiotic Rodent Isolators

“…Disinfectant activity against bacterial spores. Most of the contaminating bacteria we identified are known or presumed to form spores, 20,26,49 raising the possibility that the bacteria existed as spores during decontamination. Because spores can be more resistant to disinfection and sterilization than vegetative forms, 44 we sought to compare the killing activity of the different disinfectants against matched pairs of spores and vegetative forms.…”

“…Initial attempts to generate spores of the isolated contaminant bacteria under several previously reported induction conditions were unsuccessful. 20,26,49 Instead, we resorted to a well-established spore former, G. stearothermophilus, which is widely used as a biologic indicator for testing autoclave function. 19 Spores and vegetative forms of G. stearothermophilus were exposed briefly (15 min) to various concentrations of each disinfectant in PBS and tested for survivors by growth on agar plates.…”

“…32 Most of these bacteria are found in soil and on plants and are known or presumed to form endospores. 12,16,20,21,26,40,49 In one contamination, we also identified M. luteus, which belongs to the phylum Actinobacteria and is an obligate aerobe associated with soil, plants, and the human skin microbiome. 17 The characteristics of the contaminants do not directly allow reconstruction of the contamination routes, but they suggest that contamination occurred either via surfaces contaminated by contact with human skin (for example, hands) or unclean air or through the introduction of contaminated feed or bedding.…”