A commensal symbiosis between Prevotella bivia and Peptostreptococcus anaerobius involves amino acids: potential significance to the pathogenesis of bacterial vaginosis

In both batch and continuous culture, Peptostreptococcus anaerobius was abl e to grow in vaginal defined medium with Prevotella bivia, but not in pure culture. Growth of P. anaerobius was increased by 238% (P < 0.001) in pepto ne-supplemented vaginal defined medium conditioned by prior growth of P. bi via. Analysis of P. bivia culture supernatants showed a net accumulation of amino acids and subsequent growth of P. anaerobius in the conditioned supe rnatants resulted generally in amino acid utilization. Supplementation of p eptone-supplemented vaginal defined medium with amino acids in concentratio ns similar to those available after prior growth with P. bivia were growth- stimulatory (246%, P = 0.006) for P. anaerobius. Increased availability of amino acids by P. bivia is proposed as a mechanism to support the observed in vitro commensal symbiosis between P. bivia and P. anaerobius. (C) 1998 F ederation of European Microbiological Societies. Published by Elsevier Scie nce B.V. All rights reserved.