Proteolysis and utilization of albumin by enrichment cultures of subgingival microbiota

Abstract

Subgingival dental plaque consists mainly of microorganisms that derive their energy from amino acid fermentation. Their nutrient requirements are met by the subgingival proteolytic system, which includes proteases from microorganism and inflammatory cells, and substrate proteins from sulcus exudate, including albumin. To determine the selective effect of individual proteins on microbiota, we used albumin as the main substrate for growth. Eight subgingval plaque samples from untreated periodontal pockets of patients with adult periodontitis were inoculated in peptone yeast medium with bovine albumin (9 g/l). After three subculture steps, cell yields of the enrichment cultures at the medium with 0, 1.25, 2.5, 5, 10, and 20 g/l albumin were determined. Proteolytic activity (U/absorbance at 550 nm) of the enrichment cultures and different isolates derived from the cultures was estimated by the degradation of resorufin-labeled casein. It was observed that the yield of the mixed culture was albumin limited, and the proteolytic activities of the cultures in albumin broth were higher than in control (peptone broth). Among the isolates from the enrichment cultures, Peptostreptococcus micros, Prevotella melaninogenica, Prevotella buccae and Prevotella bivia demonstrated proteolysis. The frequent occurrence of Streptococcus gordonii and Streptococcus anginosus in the albumin cultures is explained by their ability to utilize arginine as an energy source for growth. Albumin in the medium was partly degraded by pure cultures but completely consumed in enrichment cultures, indicating synergy of bacterial proteinases. It is concluded that the subgingival microbiota possesses proteolytic activity and may use albumin as a substrate for their growth. Enrichment cultures on albumin may serve as a relatively simple in vitro model to evaluate the effects of proteinase inhibitors.

Effects of a Chlorhexidine Gluconate-Containing Mouthwash on the Vitality and Antimicrobial Susceptibility of In Vitro Oral Bacterial Ecosystems

“…The use of DGGE to monitor dynamic changes in microbial ecosystems may be complicated by the detection of nonviable organisms, since valid real-time analysis depends on rapid turnover of dead cells and the degradation of associated DNA within the test community. In this respect, the considerable proteolytic activities detected in plaque ecosystems (49) are likely to rapidly degrade dead cells, while the half-life of target DNA is likely to be low, since many streptococci and other plaque microorganisms produce (9). Validation studies in our laboratory using samples taken at 12-h time intervals suggested that turnover was considerably faster than 12 h (data not shown).…”

Comparison of Growth and Susceptibility to Sodium Hypochlorite of Mono- and Dual-Species Biofilms of Fusobacterium nucleatum and Peptostreptococcus (micromonas) micros

“…Coaggregated cells on a surface can have a combined metabolic advantage over single cells (16). P. micros degrades serum albumin (26) and glycoproteins (27) to amino acids and peptides. These peptides can be consumed by F. nucleatum (28).…”

Molecular Analysis of Microbial Diversity in Advanced Caries

“…and the Propionibacterium sp. oral strain FMA5, which accounted for 30% of the bacterial population in sample 10, have been shown to degrade proteins such as gelatin and albumin (10,24,34). Such bacteria may therefore provide peptides and amino acids required by other bacteria within the polymicrobial population.…”