Impeding Bacillus spore germination in vitro and in milk by soy glycinin during long cold storage

J Gen Appl Microbiol. 2016;62(2):52-9. doi: 10.2323/jgam.62.52.

Abstract

This paper presents a study of the magnitude and mechanism of impeding the emergent spore germination of Bacillus subtilis (non-hemolytic strain) and Bacillus licheniformis (hemolytic strain) under the action of soybean glycinin and its basic subunit (BS). Incubating B. licheniformis spores with 100 μg/ml of glycinin or BS at 35°C for 24 h totally prevented the hemolytic activity associated with the emergent vegetative cells on blood agar during 3-5 days of incubation at 35°C in contrast to the control. Glycinin and BS (100 μg/ml) also resulted in the leakage of 70 and 73% of the initially germinating spore contents of A260 absorbing materials of the two bacterial species after 2 h of incubation at 35°C, respectively. Increasing the concentration of glycinin and BS up to 400 μg/ml increased the germinating spore leakage to 83 and 88%, respectively. Spore germination in Muller Hinton Broth containing glycinin and BS (100 μg/ml) was practically nil after 4 days of incubation at 35°C. Supplementing milk preheated at 80°C/5 min with both glycinin and BS kept the final vegetative cell counts down to about 30 and 20% of the corresponding control, respectively, after 50 days of storage at 4°C. Both light, and transmission electron, microscopy images revealed significant morphological and structural distorting changes in BS-treated spores of B. licheniformis.

MeSH terms

  • Animals
  • Bacillus licheniformis / drug effects*
  • Bacillus licheniformis / physiology
  • Bacillus subtilis / drug effects*
  • Bacillus subtilis / physiology
  • Cold Temperature
  • Food Storage
  • Globulins / chemistry
  • Globulins / pharmacology*
  • Glycine max / chemistry
  • Microscopy, Electron, Transmission
  • Milk / chemistry
  • Milk / microbiology*
  • Soybean Proteins / chemistry
  • Soybean Proteins / pharmacology*
  • Spores, Bacterial / drug effects*
  • Spores, Bacterial / physiology
  • Spores, Bacterial / ultrastructure

Substances

  • Globulins
  • Soybean Proteins
  • glycinin