Microwave sterilization of growth medium alleviates inhibition of Aggregatibacter actinomycetemcomitans by Maillard reaction products

Aggregatibacter (Actinobacillus) actinomycetemcomitans is the causative agent of localized aggressive periodontitis and endocarditis. The bacteria grow slowly even in a rich medium and rapidly lose viability after about 19 h of growth. One of the reasons for the slow growth and for the decreased viability is the conventional method of making growth media by autoclaving. Faster growth and greater viability were observed in both broth and plates if the growth media were sterilized by microwave radiation rather than by autoclaving. One difference between autoclaved and microwaved media is that the autoclaved media are darker brown in color, which is known to be due to the Maillard reaction products, also known as Amadori products. The Maillard reaction products formed by autoclaving a mixture of lysine and glucose were shown to inhibit growth of A. actinomycetemcomitans. (c) 2009 Elsevier B.V. All rights reserved.