Glycine has now been noticed to be utilized as a food preservative that is harmless as a component of human diets because its inhibitory effects on bacterial growth as well as spore germination have been shown by many workers. The present studies were initiated to determine whether or not glycine is an effective food additive which would be expected to protect foods against Clostridium botulinum.
1) The effects of glycine on the germination of and outgrowth from spores of Clostridium botulinum types A, B and E were studied using two different media, ALB and thiotone, the former supporting germination only and the latter supporting both germination and subsequent outgrowth. It was found that glycine concentrations as much as 5% had only a little effect on the spore germination of all the strains tested, whereas it prevented completely the outgrowth of spores of type E, and A or B at 2 and 5%, respectively.
2) The growth tests in the complex media inoculated with small inocula of spores showed that type E strain was more sensitive to glycine than type A and B strains. Furthermore, the effectiveness of glycine was found to be dependent upon the pH of the medium; the minimum concentrations for complete inhibition of the growth of type E strain were 0.5 and 2.0% at pH 6.0 and 7.2, respectively. However, with types A and B, as much as 5% was required for complete inhibition regardless of pH.
3) The concentrations of glycine were not greatly diminished when used together with sodium nitrite or sorbic acid at respective commercially permissible amounts.
Since much higher concentrations of glycine in foods are not intended as food additives, the use of glycine appeared to be of little value against all types of Clostridium botulinum capable of causing human botulism.