Interfering mechanism of sodium bicarbonate on spore germination of Bacillus stearothermophilus

• Published in: Journal of applied microbiology Vol. 84; no. 4; pp. 619 - 626
• Main Authors: Cheung, H.Y, So, C.W, Sun, S.Q
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science Ltd 01.05.1998; Blackwell Science
• Subjects: Action of physical and chemical agents on bacteria; Bacillus stearothermophilus; Bacteriology; Biological and medical sciences; Biological Sciences; food contamination; Fundamental and applied biological sciences. Psychology; Microbiology; sodium bicarbonate; Bacillales; Germination; Concentration effect; Bacillus stearothermophilus; Sodium Hydrogencarbonates; Bacteria; Inhibition; Bacillaceae; Mechanism of action; Spores
• ISSN: 1364-5072; 1365-2672
• DOI: 10.1046/j.1365-2672.1998.00389.x

Spore germination of Bacillus stearothermophilus was progressively inhibited as the concentrations of sodium bicarbonate (NaHCO3) in the germination media increased from 0% to 1.0% (w/v). The inhibitory effect of NaHCO3 was attributed to the release of HCO3- and its alkaline properties, each of which played a different role. At low concentrations (< 0.3%), the inhibitory effect of NaHCO3 was mainly due to bicarbonate. As NaHCO3 increased from 0.3% to higher concentrations, the effect of HCO3- reached a plateau while the alkalinating effect became the more dominant inhibitory factor. Fourier transform infrared (FTIR) analysis reveals that sodium bicarbonate reacted with the carboxyl group (1570 cm-1) of some acidic amino-acid residues of protein in the spore, leading to a less orientated structure. A shift of two units towards the longer frequency for carboxyl groups indicates that a stronger interaction was formed between the carboxyl group and the Na+ ion. The largest ratio of peak height between the absorbance of carboxylate (1570 cm-1) and of amide II (1546 cm-1) of spores after pretreatment with 0.3% sodium bicarbonate reflects the biggest structural alterations of keratin-like proteins in the spore. The role of NaHCO3 in enhancing the sporicidal effect of glutaraldehyde is discussed.