Trypticase Yeast Extract Research Articles

Induction of TLR5, IRAK1, and NF-κB expression by Trichomonas vaginalis in cervical cancer cell (HeLa) and normal human vaginal epithelial cell (HVECs) lines.

Trichomoniasis is the most common non-viral sexually transmitted infection that increases the risk of cervical cancer. Trichomonas vaginalis (T. vaginalis) can regulate the pro-inflammatory cytokine production in the host cells. Toll-like receptors (TLRs) are a family of the pattern recognition receptors (PRRs) of mammalian cells, expressed in various host cells and have an important role in recognizing pathogens, and pro-inflammatory responses. The aim of the present study is to investigate the role of TLR5 in cervical cancer cells (HeLa) and human vaginal epithelial cells (HVECs) exposed to T. vaginalis. First, the cells and parasites were cultured in RPMI and trypticase yeast extract maltose (TYM), respectively. After adaption of parasite and epithelial cells by RPMI-TYM medium co-culture (9:1 vol/vol), HVECs and HeLa cells were stimulated with T. vaginalis trophozoites (24-hour incubation at 37 °C, 5% CO2). Following RNA extraction and cDNA synthesis, the gene expression levels of TLR5, IRAK1, and NF-κB were assessed using real-time PCR. Besides, the protein levels were measured using western blotting. All tests and controls were normalized using β-actin as a housekeeping control. Real-time PCR results showed an increased gene expression of TLR5, IRAK1, and NF-κB in T. vaginalis exposed HVECs and HeLa cells compared to the control group (p < 0.05). Additionally, western blot analysis showed a statistically significant increase in TLR5, and NF-κB proteins in both groups after exposure to the parasite (p < 0.05). These findings provide insight into the host-parasite interaction, and the results indicated that T. vaginalis could stimulate TLR5 and activate related pathways.

A survey on the anti-Trichomonas vaginalis effect of the hydroalcoholic extract of various medicinal plants in vitro

Background and aims: Trichomoniasis is the most common non-viral sexually transmitted infection worldwide; although it is treated by a 5-nitroimidazole drug family such as metronidazole (MTZ) with numerous side effects, and in this regard, alternative new drugs are required. Therefore, this study examined the anti-Trichomoniasis effect of the hydroalcoholic extract of some traditional medicinal plants of Iran in vitro. Methods: In this experimental study, the hydroalcoholic extracts of medicinal plants were prepared by maceration at a stock concentration of 20 mg/mL in the saline solution and then used for in vitro anti-trichomonas experiments. Trichomonas vaginalis trophozoites were isolated from the patient and cultured in a Trypticase Yeast extract Iron-Serum-33 medium. In addition, 200 μL of the culture medium containing 5×104 trophozoites was diluted in plate wells, and 10 doses were separately added on trophozoites for each extract serially diluted between 0.12 and 16 mg/mL in triplicate. The plates were incubated for 48 hours at 37 ° C with 5% CO2 . The number of trophozoites was counted with a hemocytometer and Trypan blue staining. Finally, the half maximal inhibitory concentration (IC50) was calculated by probit analysis. Results: Among the tested plants, Eugenia caryophyllata, Camellia sinensis, and Terminalia chebula Retz showed the best anti-trichomonal activity with IC50 values of 1.21, 1.62, and 1.66 mg/mL, respectively. All tested extracts had more IC50 than MTZ (IC50 100 mg/mL), an antiprotozoal drug used as a positive control. Conclusion: According to the results of this study, E. caryophylata, C. sinensis and T. chebula Retz affected the growth of T. vaginalis. Thus, it is recommended that other studies use this plant for the treatment of trichomoniasis infection.

Veillonella nakazawae sp. nov., an anaerobic Gram-negative coccus isolated from the oral cavity of Japanese children.

Two strains of previously unknown Gram-negative cocci, T1-7T and S6-16, were isolated from the oral cavity of healthy Japanese children. The two strains showed atypical phenotypic characteristics of members of the genus Veillonella, including catalase production. Sequencing of their 16S rRNA genes confirmed that they belong to genus Veillonella. Under anaerobic conditions, the two strains produced acetic acid and propionic acid as metabolic end-products in a trypticase-yeast extract-haemin medium containing 1 % (w/v) glucose, 1 % (w/v) fructose and 1 % (v/v) sodium lactate. Comparative analysis of the 16S rRNA, dnaK, rpoB and gltA gene sequences revealed that the two strains are phylogenetically homogeneous and comprise a distinct, novel lineage within the genus Veillonella. The sequences from the two strains shared the highest similarity, at 99.9, 95.8, 96.9 and 96.7 %, using the partial 16S rRNA, dnaK, rpoB and gltA gene sequences, respectively, with the type strains of the two most closely related species, Veillonella dispar ATCC 17748T and Veillonella infantium JCM 31738T. Furthermore, strain T1-7T shared the highest average nucleotide identity (ANI) value (94.06 %) with type strain of the most closely related species, V. infantium. At the same time, strain T1-7T showed the highest digital DNA-DNA hybridization (dDDH) value (55.5 %) with the type strain of V. infantium. The two strains reported in this study were distinguished from the previously reported species from the genus Veillonella based on catalase production, partial dnaK, rpoB and gltA sequences, average ANI and dDDH values. Based on these observations, the two strains represent a novel species, for which the name Veillonella nakazawae sp. nov. is proposed. The type strain is T1-7T (JCM 33966T=CCUG 74597T).

Genotyping of Trichomonas vaginalis isolates from Egypt

Background: Trichomoniasis is the most prevalent non-viral sexually transmitted infection worldwide. The outcome of infections is governed by several parasite and host factors. Molecular typing methods revealed two-type population structures for T. vaginalis, type I and type II that may differ in pathogenicity, drug resistance, and clinical presentation. Objective: To elucidate the genotype of the Egyptian isolates of T. vaginalis using multilocus sequence typing (MLST). In part, this study aims to evaluate possible relationship between genotypes and growth kinetics, metronidazole (MTZ) susceptibility and clinical presentation. Patients and Methods: Three hundred vaginal washouts were collected from Egyptian women patients aged 20-45 years suspected of having trichomoniasis. Microscopically, positive samples were cultured on modified trypticase yeast extract maltose (TYM) medium and isolates were submitted to MLST targeting three housekeeping genes namely tryptophanase (p1), alanyltRNA synthetase (p8) and DNA mismatch repair protein (p13). Results: Of the 300 samples collected, 12 (4%) proved positive for T. vaginalis by wet mount examination and culture. MLST proved that Egyptian isolates comprised two types, genotype I, constituting 70 % of the isolates and genotype II, 20 %. Mixed infection was detected in 10% of cases. No correlation was found between genotype and growth kinetics, MTZ susceptibility and clinical presentation. Conclusion: MLST is important in investigating the genetic diversity of T. vaginalis Egyptian isolates. It is recommended that a future larger multicenter study is carried out, whereby a larger number of isolates obtained from both females and males is investigated for a complete picture of genetic diversity and epidemiology.

Tannic acid-coated zeolite Y nanoparticles as novel drug nanocarrier with controlled release behavior and anti-protozoan activity against Trichomonas gallinae

In this study, a pH-sensitive drug release system was prepared by zeolite Y nanoparticles and tannic acid. Zeolite Y nanoparticles were synthesized via hydrothermal synthesis of colloidal suspensions and after that, were coated with tannic acid. In order to evaluate its performance, metronidazole as an anti-protozoan drug was loaded into nanocarriers via immersing method to study the in-vitro drug delivery behavior. This nanocomposite carriers represented pH-sensitive behavior and had more and faster release in acidic medium. In-vitro effects of metronidazole-loaded nanoparticles was measured against Trichomonas gallinae trophozoites in Trypticase Yeast extract Maltose medium. The results suggested that metronidazole-loaded and tannic acid-modified zeolite Y nanoparticles could be a potential anti-trichomonal agent.

Comparison of the Effect of Metronidazole, Tinidazole, Mango and Blueberry Extracts on Trichomonas vaginalis in Vitro

Background: Trichomoniasis is the most common nonviral sexually transmitted human disease that is caused by protozoan Trichomonas vaginalis. Metronidazole is the selective drug in trichomoniasis treatment. However, the reported cases show an increasing trend of drug resistance. This study aimed to evaluate the effect of mango and blueberry extracts on T. vaginalis. Materials and Methods: T. vaginalis was cultured axenically in TYM (Trypticase Yeast Extract) medium supplemented with 10% bovine serum. The effect of mango and blueberry extracts at 50, 100, 200, 400, 800 and 1000 μg.mL -1 on T. vaginalis was studied after 24 and 48 hours. The final numbers of parasite with a hemocytometer and Trypan blue were recorded. Then the value of IC 50 [Half maximal inhibitory concentration] and the lethal percent were calculated. In the present study, the metronidazole was used as positive control. The IC50 value of metronidazole and tinidazole were calculated in the concentrations of 0.02, 0.04, 0.08, 0.16 and 0.32 μg.mL -1 . Results: The final results confirmed the significant effect of all mango and blueberry extracts concentrations on the reduction of parasite numbers (P-value<0.05(. The extract concentrations of 1000 μg.mL -1 had the most significant effect on T. vaginalis growth inhibition after 24 hours. The IC50 values of mango and blueberry extracts, metronidazole, and tinidazole were calculated as 118.3, 60.74, 0.042 and 0.02 μg.ml -1 respectively. Conclusion: Based on the obtained results, the different concentrations of mango and blueberry extracts have significant anti Trichomonas vaginalis activities. It is suggested carrying out further studies on suitable animal models.

Trichomonas vaginalis’in Metronidazol, Ornidazol ve Proton Pompa İnhibitörleri Pantoprazol ve Esomeprazole Karşı İn Vitro Duyarlılığı

The current treatment of trichomoniasis is based on the use of 5-nitroimidazole derivatives. Although metronidazole is reliable, inexpensive and highly effective against anaerobic microorganisms and protozoa, the development of metronidazole-resistant T.vaginalis strains pose to an increasing problem. Nitroimidazoles are compounds having azomycin (2-nitroimidazole) chemical structure and are obtained from Streptomyces strains. Benzimidazole, which is found in the structure of proton pump inhibitors, is also present in the other components that have antiprotozoal activity. In this study, the in vitro susceptibility of T.vaginalis against metronidazole, ornidazole, and the proton pump inhibitors which are tested recently as antiprotozoal agents; pantoprazole and esomeprazole was investigated. For this purpose a clinical T.vaginalis strain which was formerly isolated and stored after cryopreservation process in our laboratory was used. Minimum inhibitory concentration (MIC) and minimum lethal concentration (MLC) values of those agents against to this strain were determined in vitro by dilution method in 24-well cell culture plates. Trypticase yeast extract maltose medium, horse serum and antibiotic (penicillin + streptomycin) were distributed to each well of cell culture plates and after metronidazole, ornidazole, pantoprazole and esomeprazole solutions were added to two wells for each as 800, 400, 200, 100, 50 and 25 µg/ml, followed by the addition of 1 ml 5x10(3) T.vaginalis trophozoites into each well. Plates were incubated at 37°C, and viability and motility of the trophozoites were evaluated under light microscope at 24, 48 and 72 hours after incubation. MIC and MLC values of metronidazole/ornidazole in the 72(th) hour were found as 50 µg/ml and 100 µg/ml, respectively. MIC and MLC values for pantoprazole in the 72th hour were 200 µg/ml and 400 µg/ml, while the values for esomeprazole were 400 µg/ml ve 800 µg/ml, respectively. As a result, T.vaginalis strain used in the study was susceptible to metronidazole and ornidazole, besides, it was considered that pantoprazole and esomeprazole were also effective to the parasite and could be used as alternative drugs. However, further in vitro and clinical studies are clearly needed on the antiprotozoal effects of proton pump inhibitors. To our knowledge, this study was the first in literature, which esomeprazole's susceptibility on T.vaginalis was investigated in vitro.

Is there difference of Streptococcus mutans count and adherence on amalgam and resin occlusal restorations? A blind clinical study

Aim: To compare the number of colony forming units (CFU) and agar adherence of S. mutans on amalgam (AM) and resin composite (RC) occlusal restorations. Sixty-five healthy patients older than 18 years with high caries risk who had at least one occlusal AM and RC restorations (n=130) were selected. Methods: The restorations were evaluated according to the alpha Ryge criteria (Cohen-Kappa 0.8). For each patient, a biofilm sample was taken using an impression tray technique with previously loaded with solid trypticase yeast extract cysteine sucrose with bacitracin agar placed over the AM restorations and RC restorations in the same patients. The tray was placed inside an oven at 37 °C for 48 h, and the S. mutans count was then performed. Data were analyzed with the test Wilcoxon with a 95% confidence level. Results: RC restorations had statistically significant higher number of CFU of S. mutans than AM restorations (p<0.05). Conclusions: In adult patients with high caries risk, RC occlusal surfaces showed greater agar adherence of S. mutans count than AM restorations.

Bioprospecting of Thermotolerant Bacteria from Hot Water Springs of Himachal Pradesh for the Production of Taq DNA Polymerase

Thermophilic microorganisms are adapted to live at high temperatures and produce many thermostable enzymes such as Taq polymerase, amylase, lipase, protease, etc., which find a number of commercial applications because of their thermostability. Thermal springs of Manikaran, Vashisht, Khirganga, Tattapani and Jeory of districts Kullu, Mandi and Shimla respectively, were selected for the present study and forty two thermophilic bacterial isolates were isolated using Castenholz trypticase yeast extract medium. All these thermophilic bacterial isolates were screened using morphological and biochemical characters. For molecular characterization of the selected isolates, Polymerase chain reaction was carried out for the amplification of the DNA using genus specific primers for 16S ribosomal RNA gene. Nucleotide sequences obtained after sequencing were blasted and only two isolates were found to belong to genus Thermus and the strain MS3 was found to possess maximum homology of 99 % with Thermus aquaticus. The growth parameters optimized were found to be pH of 7.5, incubation temperature 65 °C and incubation time 96 h. Taq polymerase produced using selected strain MS3, was purified by ammonium sulphate precipitation, gel permeation chromatography and ion exchange chromatography. The Taq polymerase assay with 1.5 µl purified enzyme fraction obtained after ion exchange chromatography, yielded comparable results with 0.5 µl (3.0 U/µl) of commercial Taq DNA polymerase, indicating that the protein fraction has 1.0 U/µl of DNA polymerase activity. Molecular mass of the purified Taq DNA polymerase was found to be 94,000 daltons. Protein sequencing analysis of the purified enzyme product showed 99 % homology with A-Chain structure of Taq DNA polymerase with accession number 1TAQ A.

Recovering Streptococcus mutans over restorations by the tray technique: a randomized clinical study

AIM: To correlate the tray technique for isolation and counting of Streptococcus mutans over dental restoration with the toothpick technique. METHODS: Forty 18-50-year-old patients of both genders with high cariogenic risk were selected. Inclusion criteria were: occlusal restoration evaluated as alpha, according to the Ryge's criteria (examiner' Cohen-Kappa 0.8) and 2 years old maximum age. Each patient provided a saliva sample (control group S) and two samples of dental biofilm from amalgam or resin-based composite restorations in the same patient, one obtained with the toothpick technique (group TT), and the other from homologous tooth restoration with the tray technique (group TR). This method involves only a direct impression on the occlusal surfaces by a section of a fluoride tray with trypticase yeast extract cysteine sucrose with bacitracin (TYCSB) agar previously prepared and solidified. The samples were incubated at 37 ºC for 48 h and the colony-forming units (CFU) were counted. The results were statistically analyzed with SPSS software using the linear regression method at 95% confidence level. RESULTS: TR was able to isolate S. mutans, and there was a significant positive correlation (r=0.95) with TT. There was no significant correlation between TR and control group S (r=0.47). CONCLUSIONS: TR was able to isolate and count S. mutans from the dental biofilm of dental restorations with a significant correlation with the TT group.

Tetratrichomonas spp. and Pentatrichomonas hominis are not persistently detectable after intravaginal inoculation of estrous heifers

Virgin heifers (44) were intravaginally inoculated at estrus with low (10 6) or high (10 8) doses of live Tetratrichomonas sp., Pentatrichomonas hominis ( P. hominis), or Tritrichomonas foetus ( T. foetus). Controls were inoculated with Diamond's trypticase yeast extract maltose media. Genital infection was determined by culture of cervico-vaginal mucus (CVM) in Schneider's media and InPouch TF ® as well as by polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP). The presence of trichomonads in fecal samples was determined by culture in Schneider's medium and PCR/RFLP. In CVM samples, tetratrichomonads were found by PCR/RFLP and Schneider's culture only sporadically at intermittent weeks. The presence of tetratrichomonads was not associated with the dose in the experimental vaginal inoculation since Tetratrichomonas sp. appeared more frequently in heifers inoculated with a low dose of tetratrichomonads than in heifers inoculated with a high dose of tetratrichomonads. Moreover, Tetratrichomonas spp. were isolated not only in heifers inoculated with tetratrichomonads but also in control heifers and in heifers inoculated with P. hominis. In feces, Tetratrichomonas spp. were frequently identified by culture in Schneider's and by PCR/RFLP in heifers of all groups. P. hominis was never found in CVM or feces by any method. Based on the common appearance of tetratrichomonads in feces and vaginal secretions, it appears that tetratrichomonads were detected periodically in the vagina of heifers as a consequence of repeated contamination from feces and not as a result of experimental infection. In summary, in this study, the strains of Tetratrichomonas sp. and P. hominis did not establish persistent infection in heifers.

Emergence of multiple xylitol-resistant (fructose PTS-) mutants from human isolates of mutans streptococci during growth on dietary sugars in the presence of xylitol.

The growth inhibition of mutans streptococci is one of the proposed mechanisms of action of xylitol, a caries-preventive natural carbohydrate sweetener. Xylitol is taken up and accumulated as non-metabolizable, toxic xylitol phosphate via a constitutive fructose PTS, and selects, during in vitro growth at the expense of glucose, for natural xylitol-resistant mutants that lack constitutive fructose PTS activity. Since long-term xylitol consumption leads to the emergence of xylitol-resistant mutans populations in humans in an oral environment containing sugars of dietary origin, we wanted to test the hypothesis that xylitol-resistant cells could be selected from mutans streptococci strains during in vitro growth on fructose, sucrose, or lactose. Three laboratory strains and three fresh mutans streptococcal isolates were repeatedly transferred in trypticase-yeast extract medium supplemented with glucose, fructose, sucrose, or lactose in the presence and absence of xylitol. Depending on the growth sugar, the presence of xylitol resulted in the selection of xylitol-resistant populations for several of the six strains tested, but not necessarily in the presence of all four sugars. All six strains rapidly became xylitol-resistant when grown on glucose in the presence of xylitol. All three fresh isolates became xylitol-resistant after 9 to 16 transfers in the presence of fructose or sucrose plus xylitol, while none of the laboratory strains became xylitol-resistant after 16 transfers in the presence of these sugars. The growth rates of 12 xylitol-resistant mutants in the presence of eight sugars suggested the existence of various types of xylitol-resistant mutants. The data partially explain the occurrence of xylitol-resistant mutans populations in long-term xylitol consumers and suggest a mechanism consistent with a selection process. Since various preliminary results suggest that xylitol-resistant natural mutants may be less virulent and less cariogenic than their parent strains, this selection process may alter, for the better, the mutans streptococci population of the plaque and play a role in the caries-preventive action of xylitol.

Characterization of immunoglobulin G‐degrading proteases of Prevotella intermedia and Prevotella nigrescens

Degradation of immunoglobulins is thought to be an important factor in the causation of periodontal diseases by hindering local host defenses and by providing nutrients to the periodontal microflora. In this study, we characterized the proteolytic activity against human immunoglobulin G (IgG) of 20 strains of Prevotella intermedia and Prevotella nigrescens isolated from periodontal pockets and oral abscesses. IgG degradation was studied by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. All strains degraded IgG within 48 h after growth in trypticase-yeast extract medium (TY) supplemented with 0.3% IgG. Incorporating IgG in TY broth enhanced bacterial growth. Protease profiles (zymography), which revealed the presence of 1-4 IgG-degrading proteolytic bands in bacterial cell extracts, became more complex after growth in the presence of IgG. A 38-kDa protease capable of degrading IgG nonspecifically was present in almost all strains. The proteolytic activity was mainly located on the surface of the cell envelope. Two strains of P. intermedia and P. nigrescens ATCC 33563 were selected for further studies. Bacterial cell suspensions in phosphate-buffered saline completely degraded human IgG, IgA and IgM within 24 h. This activity depended on reducing conditions and was inhibited at temperatures above 50 degrees C. The pH optimum of immunoglobulin degradation was at pH 7. Strains cultured at 42 degrees C showed a markedly reduced capacity to degrade IgG. Inhibition studies revealed that breakdown of IgG was caused by a cysteine protease(s). The capacity of P. intermedia and P. nigrescens to degrade immunoglobulins may explain their association with polymicrobial oral diseases.

Glucan-binding proteins of Streptococcus sobrinus B13 grown in high glucose media

To improve the yield of an 87-kDa glucan-binding protein (GBP) of Streptococcus sobrinus B13 (serogroup d), trypticase-yeast extract (TYE) medium supplemented with higher (1 and 2%) than the usual amount (0.2%) of glucose was used for growth. The production of this GBP extracellularly in 1.0 and 2.0% glucose-TYE media was examined and compared with the control (0.2% glucose). Upon analysis using SDS-PAGE, extracellular culture concentrates of 1.0 and 2.0% glucose-TYE cultures revealed similar protein profiles as the control. Higher glucose concentrations did not inhibit the synthesis of the 87-kDa GBP. Cells grown in 1.0 or 2.0% glucose-supplemented media aggregated rapidly compared to those observed in the control cells (0.2% glucose grown). Higher cell yield and higher extracellular protein content were obtainable in both 1.0 and 2% glucose-TYE cultures, thus improving the yield of the 87 kDa GBP.

Alcohols Protect Escherichia coli against Cold Shock

Alcohols protect Escherichia coli against cold shock, and the concentration of alcohol which provided optimal protection declined with increasing hydrophobicity of the alcohol. The rate of loss of viability after the chilling transition was decreased by n-octanol, even when it was added after that chilling transition. Cold-shocked cells exhibited a sensitivity toward dioxygen, seen as greater enumeration on anaerobic, rather than on aerobic, trypticase-yeast extract agar plates, and addition of catalase or antioxidants, such as alpha-tocopherol or probucol, to the agar plates did not lessen this dioxygen sensitivity. Respiratory capacity was diminished by cold shock, and cyanide-sensitive respiration was more affected than was cyanide-resistant respiration. Discharging the proton gradient, with the uncoupler carbonyl cyanide trifluoromethoxy-phenylhydrazone, did not change sensitivity to cold shock. There was no evidence for minimal medium recovery after cold shock. The data presented, as well as that already in the literature, are explained on the basis of membrane damage caused by patches of ordering transitions in one membrane leaflet, unmatched by comparable transitions in the mating leaflet.

Characterization of volatile sulphur production by pathogenic and non-pathogenic strains of oral Bacteroides

Marked differences were observed in intermediate sulphur metabolism between non-pathogenic strains of Bacteroides melaninogenicus var melaninogenicus (CP −) and pathogenic Bacteroides melaninogenicus asaccharolyticus (CP +). The CP+ strains, which produced collagenase and protease and caused formation of abscesses when injected subcutaneously into groins of guinea pigs, produced copious amounts of volatile sulphur compounds (VSC) which consisted predominantly of CH 3SH and (CH 3S) 2. Hydrogen sulphide occurred in considerably lesser amounts. CP+ cultures yielded 8-fold more total volatile S, 15-fold more CH 3SH and 260-fold more (CH 3S) 2 during 24 h of incubation in trypticase-yeast extract medium. Whereas H 2S accounted for 60 per cent of the total volatile S content of the head-space of CP− cultures, it represented only 8 per cent of the volatile S in CP+ systems. Although the CP− organisms did not grow as well as CP +, the differences in concentration of VSC may be only partly related to the disparity in growth rates. When the VSC concentrations were calculated on the basis of equivalent optical density of 1.0, the CP+ strains still produced over 3-fold more total volatile S, 6-fold more CH 3SH and 100-fold more (CH 3S) 2. A similar allowance for growth rate suggests that CP− strains may possess a greater potential to produce H 2S. Both groups metabolized S-containing amino acids and serine, resulting in appreciable increases in H 2S production by CP−. However, the two groups appeared to metabolize the carbon moeity of cystine and cysteine by different pathways. The addition of glucose to the medium depressed total volatile S production by both CP+ and CP− strains, attributable mostly to lower H 2S levels. Whereas the omission of yeast extract and charcoal treatment of trypticase did not adversely effect the activity of CP +, it further markedly reduced the capacity of CP− cultures to produce VSC. These results suggest that VSC analysis offers a convenient means of assessing strain differences and pathogenic potential of B. melaninogenicus.

The predominant cultivable flora of tooth surface plaque removed from institutionalized subjects

Tooth surface plaque was removed from 11 institutionalized individuals and cultured on agar plates in an anaerobic chamber. The recovery of organisms on a dilute trypticase yeast extract medium (MM10), incubated anaerobically, averaged 33 ± 26 per cent of the microscopic count. Growth on MM10, under aerobic conditions averaged 8 ± 5 per cent. The anaerobe to aerobe recovery ratio on medium MM10 was about 4. Six hundred and seventy-one isolates grew on subculture and were partially characterized. About half the isolates were not capable of lowering the pH in glucose broth below 5·5. Streptococci accounted for about 38 per cent of the isolates and were found in each subject. A sub-group of 15 strains grew in 40 per cent bile, formed NH 3 from arginine, fermented salicin, but not inulin. These isolates possessed characteristics of Streptococcus sanguis and Streptococcus mitis. Various Actinomyces species comprised about 14 per cent and Clostridium species accounted for 8 per cent of the cultivable flora. Bacteroides melaninogenicus, Fusobacterium species, and Veillonella species each were about 6 per cent of the isolates. The overall character of these plaque isolates suggested that a gingival crevice microflora containing several amino-acid fermenting species had colonized the tooth surfaces. These organisms would not be expected to produce a plaque capable of decalcifying enamel, which might explain why these subjects had a low caries experience.

Amino acid fermentation by Bacteroides melaninogenicus.

Each of four strains ofBacteroides melaninogenicus grew well in a trypticaseyeast extract medium, without carbohydrate. Addition of glucose did not increase growth, and the sugar was fermented to only a limited extent. However, growth decreased when the trypticase concentration of the medium was reduced. These observations suggest that amino acid fermentation is of major importance in the energy metabolism ofB. melaninogenicus. Acetic, butyric and isovaleric acids were produced by all four strains. Two of the strains also formed propionic and isobutyric acids. Experiments using media containing either labeled glucose or labeled protein indicated that these acids are primarily derived from the proteinaceous substrates in the medium, rather than from glucose, indicating that amino acid fermentation byB. melaninogenicus is not subject to glucose repression. Resting-cell suspensions ofB. melaninogenicus possessed a limited ability to ferment free acids, as judged by the liberation of ammonia. However the organisms readily fermented amino acids when present as peptides, suggesting that peptides are more readily transported into the cell. Three of the 4 strains studied grew well when incubated under an atmosphere containing 2 to 4 % oxygen in cultures possessing a high surface to volume ratio. Hence not all strains ofB. melaninogenicus can be considered strict anaerobes.

Function of growth factors for rumen microorganisms. I. Nutritional characteristics of Selenomonas ruminantium.

Nutritional characteristics of Selenomonas ruminantium var. lactilytica isolated from a sheep rumen were studied. The organism required for growth the addition of a clarified rumen fluid to a Trypticase-yeast extract medium with either lactate or glucose as an energy source. The requirement for rumen fluid was found to be satisfied by volatile fatty acids in glucose media and by biotin in lactate media. Straight-chain saturated fatty acids with C(3) to C(10) carbon skeleton had been found to be effective. Among them, n-valerate was most effective at the lowest concentration. An abnormal morphology was observed with n-valerate-deficient glucose media. n-Valerate was essential in glucose media, and it was stimulatory in lactate media. Fermentation products from glucose were lactate, propionate, and acetate, and fermentation products from lactate were propionate and acetate. When cells were grown in a glucose medium containing n-valerate-C(14), the label was present in cell fractions. Almost all of the activity was found in lipid materials.

OBSERVATIONS ON AMYLOLYTIC BACTERIA: I. A SURVEY OF NAMED MESOPHILIC SPECIES ON SOLUBLE STARCH

A survey was made of the ability of known, named, mesophilic strains of 40 bacterial species lo hydrolyze soluble starch in trypticase–yeast extract broth. The 40 species are either not described in Bergey's Manual as to their action on starch or they are listed as "not hvdrolyzing starch". Strains of 35 species hydrolyzed soluble starch, including seven spp. described as nonamyloytic. The latter were: Micrococcus pyogenes var. aureus, M. citreus, M. luteus, Escherichia coli, Erneinia carotovora, E. atroscptica, and Flazobacterium rhenanus. Strains of lour species failed to hydrolyze starch in repeated at tempts: Micrococcus sphaeroides, Goffkya tetragene, Neisseria catarrhalis, Serratia, rubida, Rhizobium trifolii failed to grow. The disappearance of the substrate is a more permanent characteristic than either the accumulation of acids or of reducing sugars. Additional tests are required when the starch iodine color is still blue after two weeks of incubation. The initial pH seems to influence amylase formation. Pertinent literature is quoted supporting the findings.