Role of stereospecific nature of germinants in Bacillus megaterium spores germination

Abstract

The present study was undertaken with the objective to assess the effect of distinct stereoisomeric forms of nutrient germinants (selected sugars and amino acids) on the process of germination onset in dormant spores of MTCC 2949. In this respect, epimers of glucose and enantiomers of alanine were employed in current work. When supplemented with these stereoisomers, spores were found germinated only with d-glucose and d-mannose among epimers of glucose and only with l-alanine among enantiomers of alanine. Interestingly, germination in spores was observed to negligible extent with d-galactose and d-alanine. These findings were obtained on the basis of four type of germination assays, namely reduction in absorbance measured at 600 nm (≤5 to ≥30%), refractility examination (phase bright and dark), esterase assay [fluorescence units 0.455-94.62 (×10)] and fluorescent staining (fluorescent/non-fluorescent signals). Understanding of spores germination process and efficacy of different forms of germinants to trigger germination is of immense importance. It aids in development of sensing and sterilization indicating tools employing chiefly spores as biorecognition elements and in uncovering the mechanism of diseases, food contamination and spoilages resulting from the germination of spores. The findings of current work support the possibility to explore such germination mechanism by significantly giving the clue for potential existence of stereospecific receptor sites on the surface of spores. Perhaps, these sites can specifically differentiate and recognize stereoisomerically diverse forms of germinants for induction of germination.

SUGARS MEDIATED GERMINATION IN SPORES OF Bacillus megaterium

“…loss i.e., < 5% shown by dormant spores incubated without sugar and thus proved their non-germinant characteristic. Similarly, germination in spores of B. megaterium QM B1551 in response to D-glucose, glucosamine, 2-deoxy-Dglucose, sorbose, L-alanine and L-proline while no germination in response to rhamnose and galactose was also reported in other work which supports the findings obtained in presented investigation [16,17,10].…”

“…Spores in Bacillus megaterium were produced by using nutrient starvation principle based method [9,10]. Loopful of fresh culture of B. megaterium from nutrient agar medium (Himedia, India) was inoculated in trypton glucose yeast extract broth, propagation medium and incubated at 37°C for 24 h. One mL of developed inoculum was transferred to 100 mL propagation medium and further incubated at 37°C for 48 hrs.…”

“…Spore germination studies: Germination in spores of B. megaterium in response to eleven sugars, was assessed by monitoring O.D. (600 nm) and refractility examination [10]. Each of these assays was performed with spores at an O.D.…”

Sporulation, Structure Assembly, and Germination in the Soil Bacterium Bacillus thuringiensis: Survival and Success in the Environment and the Insect Host

“…Indeed, B. licheniformis genomes contain a pentacistronic ynd operon, the yndD, yndE3, yndE2, yndF1, and yndE1 genes, encoding A, B, B, C, and B GR subunits, respectively (subscripts indicate paralogs). In contrast to the B subunits of Ynd, the B subunit of GerA was essential for amino-acid-induced germination [220,235,239,240]. Therefore, in addition to the operon organization of the GR receptors, dynamic structural studies have provided novel insights into the role of individual GR subunits involved in the cooperative interaction among GR, in triggering spore germination [220,235,239,240] (Figure 3).…”

“…In contrast to the B subunits of Ynd, the B subunit of GerA was essential for amino-acid-induced germination [220,235,239,240]. Therefore, in addition to the operon organization of the GR receptors, dynamic structural studies have provided novel insights into the role of individual GR subunits involved in the cooperative interaction among GR, in triggering spore germination [220,235,239,240] (Figure 3). As outlined in Figure 1A,B, dormant spores can awake in several ways: (1) by external stimuli, external environmental signals; (2) in the host by nutrients; (3) by germinants receptors (GR) present in the inner membrane or in the outer membrane; (4) by other components such as CwLJ, or directly signal through SPoVA (independently of GR).…”