Analysis of Clostridium botulinum toxigenic types A, B, and E for fatty and carbohydrate content.
Lyophilized, 48-hr log-phase vegetative cells were extracted with chloroform-methanol (2:1, v/v) and ethanol-ether (3:1, v/v) and then saponified with methanolic KOH. Gas-liquid chromatography of the methyl esters of extractable fatty acids revealed distinctive "pattern profiles" of Clostridium botulinum toxigenic types "A," "B," and "E." C. perfringens type "A" and Escherichia coli strain "B" were also studied in a similar manner and were found to give pattern profiles which were distinct even from those obtained for the C. botulinum microorganisms. Amino sugar content of the five microorganisms was determined by using a Beckman amino acid analyzer. The molar ratio of glucosamine to that of galactosamine was found to be of further assistance in distinguishing the individual microorganisms.
Serological Studies of Clostridium botulinum Type E and Related Organisms
Clostridium botulinum type E antigens prepared from washed cells by either Formalin treatment or heating at 100 C were used for immunizing rabbits. Agglutination tests showed that high levels of antibody were produced by both types of preparations. Flagellar antigens were highly strain-specific, whereas the somatic antigens were sufficiently similar to produce complete cross-agglutination. One toxigenic strain produced toxigenic and nontoxigenic progeny which were physiologically and antigenically identical in all other respects. Other nontoxigenic strains whose growth, physiological, and morphological characters were identical to type E and strains which had some physiological differences completely cross-agglutinated with type E strains via the somatic antigen. Neither type of antiserum agglutinated other clostridia against which they were tested except for C. acetobutylicum. This reaction seems to be due to a nonspecific anamnestic response and does not appear to be related to the immunizing strains. The nontoxigenic strains studied seem to have no greater antigenic differences from type E strains than the type E strains have from each other.
Synergistic Effect of High Temperature and High pH on the Destruction of Salmonella enteritidis and Escherichia co1i O157:H7.
This study was undertaken to determine if high temperature and high pH interact synergistically to enhance the rate of destruction of two important gram-negative foodborne pathogens, Escherichia coli O157:H7 and Salmonella enteritidis . The rates of destruction in NaHCO3-NaOH buffers at pH 7.0, 10.0, and 11.0 were determined at 35, 40, 45, 50, 55, 60, and 65°C. Use of an improved heating protocol eliminated a "tailing effect" at longer exposure times. The present study demonstrated that the combination of high pH and high temperature resulted in a highly significant synergistic interaction (P > F = 0.0001), which caused rapid death of both E. coli O157:H7 and S. enteritidis . This "alka-therm" technology might be used commercially to destroy gram-negative foodborne pathogens on various raw agricultural commodities.