Peptone-yeast Medium Research Articles

Proteolysis and utilization of albumin by enrichment cultures of subgingival microbiota.

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.

Phagocytosis of the protozoonTetrahymena pyriformisas an endpoint in the estimation of cocaine salt and cocaine freebase toxicity

Cells of the ciliated protozoon Tetrahymena pyriformis strain W, grown in a peptone-yeast medium, usually contain many phagocytic vacuoles. The phagocytic activity of this protozoon was studied in vivo using heat-inactivated yeast stained with carmine after exposing the cultures for 1 hour to different doses of cocaine hydrochloride or cocaine freebase (crack) (0.5, 1 or 2 mg/100 ml of protozoan culture).The number of vacuoles formed indicated the phagocytic activity. Cocaine hydrochloride and crack caused a decrease of the phagocytic activity of the protozoon (p < 0.05) when compared to the control cultures. Furthermore, the two chemical forms of cocaine, salt and free-base respectively, caused quantitatively different effects on the phagocytic activity. Crack produced an extensive decrease in phagocytosis, compared to equal concentrations of cocaine hydrochloride. These results suggest a possible relationship between cocaine abuse and the suppression of phagocytosis that may contribute to the impairment of immunity in drug misusers.

Direct conversion of cellulosic materials to hydrogen by Clostridium sp. strain no. 2

We investigated hydrogen production by fermentation of enzymatic hydrolysates of Avicel and xylan, using Clostridium sp. strain no. 2. At 0.3% concentration in peptone yeast (PY) medium, pure xylose or glucose and crude hydrolysates of Avicel or xylan were converted to hydrogen at yields of 16.1 mmol or 14.6 mmol and 19.6 mmol or 18.6 mmol, per gram of substrate consumed, respectively. Alternatively, a batch culture of strain no. 2 grown in PY medium containing 1% of xylan or xylose with crude xylanase preparation and xylose alone as a reference, gave hydrogen production of 9.5 mmol or 9.6 mmol and 10.3 mmol, per gram of substrate supplemented, respectively.

The effects of morphine, cocaine, amphetamine and hashish on the phagocytosis of the protozoon Tetrahymena pyriformis strain W

Cells of the ciliated protozoon Tetrahymena pyriformis, strain W, grown in a peptone-yeast medium usually contain many phagocytic vacuoles. The phagocytic activity of this protozoon was studied in vivo using heat-killed yeast stained with carmine dye and after exposing the cultures for 2 hr to morphine (20 μg/ml), cocaine (20 μg/ml), amphetamine (0.5 μg/ml) or hashish (0.1 μg/ml). The number of vacuoles formed indicated the phagocytic activity after treatment with the drugs of abuse. Amphetamine caused a slight increase ( P < 0.05) in the phagocytic activity of the protozoon, whereas morphine, cocaine and hashish each caused a significant ( P < 0.01) decrease in this activity.

Variability in growth and fermentation products of Clostridium sporogenes inoculated into canned foods and grown in laboratory media for various time intervals

Previous studies on the use of gas-liquid chromatography (GLC) in solving food spoilage problems have proven the technique to be rapid, simple and inexpensive. However, the limitation of this approach is the effect of food composition on metabolic activity as reflected in the GLC profile of the organism involved. In this study, the influence of the food composition and incubation time upon the fermentation end-product patterns of Clostridium sporogenes was investigated. The results illustrated the fact that each of these environmental variables had a profound effect on the GLC profile. When the test organism was grown in peptone yeast (PY) medium with or without 1% glucose, the characteristic profile was detected only after 24 h which corresponds to the stationary phase of growth. An initial lag (12 h) of glucose utilization was observed. Glucose supplementation of the PY medium resulted in certain metabolic activities which are explained by reference to known physiological facts. Examples include the production of higher amounts of alcohol, especially ethanol, the production of iso-amyl alcohol and the suppression of certain branched chain amino acids. A proposal is made to show how the interaction of bacteria with environmental variables could be studied systematically.

Peculiarities of fatty acid composition of the genusCaulobacter

The fatty acid composition of 35 strains of stalked bacteria belonging to 17 of the hitherto described 19 species and 10 unidentified strains of the genusCaulobacter was studied. ll-Methyl-cis-octadec-11-enoic acid presumably synthesized fromcis-vaccenic acid was detected in all the strains in amounts of 0.4 – 34.7 % and was considered as a chemotaxonomic marker of the genus. During growth on a peptone-yeast medium, the caulobacters synthesized, along with the fatty acids which are typical of gram-negative bacteria, some normal and branched fatty acids with 15 and 17 carbon atoms (1–49 %). The synthesis of these acids was inhibited by glucose. The cell shape of stalked bacteria (fusiform, vibrioid or bacteroid) is not obviously associated with the contents of individual fatty acids.

Isolation of a bile salt sulfatase-producing Clostridium strain from rat intestinal microflora

Bile acid sulfates, formed in human and rat livers, are desulfated by the intestinal microflora. In our study we first isolated from conventional rat feces an unnamed bacterium, termed strain S1, which desulfated the 5 beta-bile salt 3 alpha-sulfates in vitro and in vivo after association with gnotobiotic rats. Strain S1 also possessed 12 alpha-hydroxysteroid dehydrogenase and bile salt-deconjugating activities. The strain was a strict anaerobic, CO2-requiring, gram-negative, sporeforming rod and was designated as belonging to the genus Clostridium. Growth was scarce in culture media, unless in the presence of 0.1% taurine, a sulfur-containing amino acid. Addition of this substance raised the number of bacteria in thioglycolate and peptone yeast media from 10(4) per ml to 10(6) to 10(7) per ml and increased the colony diameter on agar medium from 0.2 mm to 0.5 to 0.9 mm. Sulfatase activity was specific for the 5 beta-bile salt sulfates, leaving the 5 alpha-bile salt sulfates unchanged. In addition, the sulfatase activity was cell bound, and its production was dependent on the composition of the culture medium, although no minimal sulfur medium was required for sulfatase activity.