FACTORS INFLUENCING THE GROWTH AND VIABILITY OF ACTINOBACILLUS-ACTINOMYCETEMCOMITANS

The metabolic requirements for the routine growth of Actinobacillus ac tinomycetemcomitans were investigated by the addition of nutrients to conventional bacteriological and tissue culture media. Commonly used t issue culture media required fetal bovine serum as an additive to sust ain bacterial growth rates comparable to those obtained with bacteriol ogical media. The addition of increasing concentrations of yeast extra ct to bacteriological medium increased the growth rate of several A. a ctinomycetemcomitans strains. In an attempt to identify the components of yeast extract that enhanced the growth of A. actinomycetemcomitans , a number of vitamins, essential and non-essential amino acids were t ested for their role in promoting growth. The addition of L-cystine re sulted in bacterial growth rates comparable to those with yeast extrac t. Thiamine increased the growth of several A. actinomycetemcomitans s trains but did not result in growth rates comparable to those with yea st extract. The addition of physiological concentrations of steroid ho rmones to bacteriological medium enhanced the growth of A. actinomycet emcomitans. Additional iron compounds and fat-soluble vitamins had no influence on A. actinomycetemcomitans growth. However, the requirement of iron for bacterial growth remains unclear. The optimal pH range fo r growth of A. actinomycetemcomitans was between pH 7.0-8.0 in a mediu m containing 0.5-1% NaCl. Several interesting observations on the viab ility of A. actinomycetemcomitans were made. A rapid reduction of A. a ctinomycetemcomitans viability occurred following suspension in distil led water. The presence of the detergent Triton X-100 at concentration s above 2% (v/v) also decreased the viability of A. actinomycetemcomit ans within 10 min.