Role of small, acid-soluble spore proteins in the resistance of Clostridium perfringens spores to chemicals

Characterization of Clostridium perfringens Spores That Lack SpoVA Proteins and Dipicolinic Acid

“…However, if P 41 is present in C. perfringens spoVA spores, perhaps this protease can catalyze some SASP hydrolysis in the more hydrated core of spoVA spores. Given the important role played by ␣/␤-type SASP in C. perfringens spore resistance (45,49,50), it was thus of interest to compare the levels of ␣/␤-type SASP in C. perfringens spoVA and wild-type spores. Polyacrylamide gel electrophoresis at low pH of a SASP extract from wild-type and spoVA spores gave only a tight group of protein bands (Fig.…”

“…(i) The increased hydration of the DPA-less spores allows more rapid reaction of reactive chemicals with either DNA saturated with ␣/␤-type SASP or other targets in the spore core, such as proteins. (ii) While the levels of ␣/␤-type SASP in the DPA-less spores are normal, a significant amount of these proteins may not be bound to the DNA because a higher core water content promotes their dissociation, a process known to take place in fully germinated B. subtilis spores that have a core water content comparable to that in growing cells (52); this protein-free DNA would then be very sensitive to DNA-damaging chemicals, as is the case in B. subtilis and C. perfringens spores (45,49,50,63). Analysis of whether hydrogen peroxide kills DPA-less C. perfringens spores by DNA damage might resolve this issue, as at least with B. subtilis spores, DNA is so well protected by ␣/␤-type SASP that this agent does not kill these spores by DNA damage, although it does cause lethal DNA damage in B. subtilis spores that lack most ␣/␤-type SASP (57,63).…”

“…The resistance of C. perfringens spores to chemicals was determined as described previously (45). Briefly, purified spores at an OD 600 of ϳ1 were treated as follows.…”

“…(ii) SpoVA proteins and Ca-DPA release are not required for C. perfringens spore germination. (iii) A low spore core water content is essential for full resistance of C. perfringens spores to moist heat, UV radiation, and chemicals.Clostridium perfringens food poisoning is caused mainly by enterotoxigenic type A isolates that have the ability to form metabolically dormant spores that are extremely resistant to heat, radiation, and toxic chemicals (45,49,50,55). These highly resistant spores can survive traditional methods for cooking meat and poultry products as well as other processing treatments used in the food industry.…”

“…The factors involved in Bacillus subtilis spore resistance include the following: (i) relatively impermeable spore inner membrane; (ii) low water content of the spore core; (iii) high levels of pyridine-2,6-dicarboxylic acid (dipicolinic acid [DPA]) in the spore core and the type and amount of cations chelated by DPA; and (iv) the saturation of spore DNA with ␣/␤-type small, acid-soluble spore proteins (SASP) (63,64). Studies have shown that ␣/␤-type SASP are also an important factor in C. perfringens spore resistance to moist heat, UV radiation, and some chemicals (45,49,50), while small changes in the water content of the cores of these spores alter resistance to moist heat and nitrous acid (46). Spore germination has been well studied in B. subtilis (34,62) and can be initiated by a variety of compounds (termed germinants) including amino acids and some other nutrients and nutrient mixtures, a 1:1 chelate of Ca 2ϩ and DPA (Ca-DPA), cationic surfactants, and hydrostatic pressure (41,44).…”