Mouth Bacteria Biofilms Induce Acid Tolerance, Promote Cavities

2007 ◽  
Vol 2 (10) ◽  
pp. 499-499
Keyword(s):  
Acid Tolerance

All-trans retinoic acid: tolerance and biologic effects in myelodysplastic syndrome.

1993 ◽  
Vol 11 (8) ◽  
pp. 1489-1495 ◽  
Author(s):  
R Kurzrock ◽  
E Estey ◽  
M Talpaz
Keyword(s):  
Retinoic Acid ◽  
Side Effects ◽  
Myelodysplastic Syndrome ◽  
Acid Tolerance ◽  
Maximum Tolerated Dose ◽  
Significant Activity ◽  
Trans Retinoic Acid ◽  
All Trans Retinoic Acid ◽  
Biologic Effects ◽  
Dose Levels

PURPOSE We conducted a study to evaluate the tolerance to and biologic effects of all-trans retinoic acid in patients with myelodysplastic syndrome. PATIENTS AND METHODS Thirty-nine patients with myelodysplastic syndrome were treated with oral all-trans retinoic acid for 6 weeks. Dose levels were 10, 25, 50, 100, 150, 200, and 250 mg/m2/d. At least three patients were treated on each dose level. RESULTS The most common side effects were mucocutaneous dryness and erythema, and hypertriglyceridemia. Dose-limiting side effects were diverse and included dermatitic problems, sensorineural hearing loss, headaches, nausea and vomiting, myalgias, and dyspnea. The maximum-tolerated dose was 150 mg/m2/d. Only one response was seen among 29 patients considered assessable for response. CONCLUSION All-trans retinoic acid can be safely administered to patients at doses up to 150 mg/m2/d for 6 weeks. However, as administered in this study, this compound does not appear to have significant activity in myelodysplastic syndromes.

scholarly journals A Novel Microbial Zearalenone Transformation through Phosphorylation

Toxins ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 294
Author(s):  
Yan Zhu ◽  
Pascal Drouin ◽  
Dion Lepp ◽  
Xiu-Zhen Li ◽  
Honghui Zhu ◽  
...  
Keyword(s):  
Microbial Transformation ◽  
Acid Tolerance ◽  
Transformation Product ◽  
The United States ◽  
Corn Silage ◽  
Rrna Gene ◽  
Bacillus Spp ◽  
High Concentrations ◽  
The 16S Rrna Gene ◽  
Bacillus Strains

Zearalenone (ZEA) is a mycotoxin widely occurring in many agricultural commodities. In this study, a purified bacterial isolate, Bacillus sp. S62-W, obtained from one of 104 corn silage samples from various silos located in the United States, exhibited activity to transform the mycotoxin ZEA. A novel microbial transformation product, ZEA-14-phosphate, was detected, purified, and identified by HPLC, LC-MS, and NMR analyses. The isolate has been identified as belonging to the genus Bacillus according to phylogenetic analysis of the 16S rRNA gene and whole genome alignments. The isolate showed high efficacy in transforming ZEA to ZEA-14-phosphate (100% transformation within 24 h) and possessed advantages of acid tolerance (work at pH = 4.0), working under a broad range of temperatures (22–42 °C), and a capability of transforming ZEA at high concentrations (up to 200 µg/mL). In addition, 23 Bacillus strains of various species were tested for their ZEA phosphorylation activity. Thirteen of the Bacillus strains showed phosphorylation functionality at an efficacy of between 20.3% and 99.4% after 24 h incubation, suggesting the metabolism pathway is widely conserved in Bacillus spp. This study established a new transformation system for potential application of controlling ZEA although the metabolism and toxicity of ZEA-14-phosphate requires further investigation.

scholarly journals Eukaryotic translation factor eIF5A contributes to acetic acid tolerance in Saccharomyces cerevisiae via transcriptional factor Ume6p

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Yanfei Cheng ◽  
Hui Zhu ◽  
Zhengda Du ◽  
Xuena Guo ◽  
Chenyao Zhou ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Acetic Acid ◽  
Adaptive Response ◽  
Acid Tolerance ◽  
Peptide Bond ◽  
Transcriptional Factor ◽  
Yeast Cells ◽  
Acetic Acid Tolerance ◽  
Translation Factor ◽  
Industrial Strains

Abstract Background Saccharomyces cerevisiae is well-known as an ideal model system for basic research and important industrial microorganism for biotechnological applications. Acetic acid is an important growth inhibitor that has deleterious effects on both the growth and fermentation performance of yeast cells. Comprehensive understanding of the mechanisms underlying S. cerevisiae adaptive response to acetic acid is always a focus and indispensable for development of robust industrial strains. eIF5A is a specific translation factor that is especially required for the formation of peptide bond between certain residues including proline regarded as poor substrates for slow peptide bond formation. Decrease of eIF5A activity resulted in temperature-sensitive phenotype of yeast, while up-regulation of eIF5A protected transgenic Arabidopsis against high temperature, oxidative or osmotic stress. However, the exact roles and functional mechanisms of eIF5A in stress response are as yet largely unknown. Results In this research, we compared cell growth between the eIF5A overexpressing and the control S. cerevisiae strains under various stressed conditions. Improvement of acetic acid tolerance by enhanced eIF5A activity was observed all in spot assay, growth profiles and survival assay. eIF5A prompts the synthesis of Ume6p, a pleiotropic transcriptional factor containing polyproline motifs, mainly in a translational related way. As a consequence, BEM4, BUD21 and IME4, the direct targets of Ume6p, were up-regulated in eIF5A overexpressing strain, especially under acetic acid stress. Overexpression of UME6 results in similar profiles of cell growth and target genes transcription to eIF5A overexpression, confirming the role of Ume6p and its association between eIF5A and acetic acid tolerance. Conclusion Translation factor eIF5A protects yeast cells against acetic acid challenge by the eIF5A-Ume6p-Bud21p/Ime4p/Bem4p axles, which provides new insights into the molecular mechanisms underlying the adaptive response and tolerance to acetic acid in S. cerevisiae and novel targets for construction of robust industrial strains.

scholarly journals Acid tolerance in early colonizers of oral biofilms

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Gabriella Boisen ◽  
Julia R. Davies ◽  
Jessica Neilands
Keyword(s):  
Acid Tolerance ◽  
Low Ph ◽  
Salivary Proteins ◽  
Confocal Scanning Laser Microscopy ◽  
Planktonic Cells ◽  
Tolerance Development ◽  
Salivary Pellicle ◽  
Oral Biofilms ◽  
Acid Tolerant

Abstract Background In caries, low pH drives selection and enrichment of acidogenic and aciduric bacteria in oral biofilms, and development of acid tolerance in early colonizers is thought to play a key role in this shift. Since previous studies have focussed on planktonic cells, the effect of biofilm growth as well as the role of a salivary pellicle on this process is largely unknown. We explored acid tolerance and acid tolerance response (ATR) induction in biofilm cells of both clinical and laboratory strains of three oral streptococcal species (Streptococcus gordonii, Streptococcus oralis and Streptococcus mutans) as well as two oral species of Actinomyces (A. naeslundii and A. odontolyticus) and examined the role of salivary proteins in acid tolerance development. Methods Biofilms were formed on surfaces in Ibidi® mini flow cells with or without a coating of salivary proteins and acid tolerance assessed by exposing them to a challenge known to kill non-acid tolerant cells (pH 3.5 for 30 min) followed by staining with LIVE/DEAD BacLight and confocal scanning laser microscopy. The ability to induce an ATR was assessed by exposing the biofilms to an adaptation pH (pH 5.5) for 2 hours prior to the low pH challenge. Results Biofilm formation significantly increased acid tolerance in all the clinical streptococcal strains (P < 0.05) whereas the laboratory strains varied in their response. In biofilms, S. oralis was much more acid tolerant than S. gordonii or S. mutans. A. naeslundii showed a significant increase in acid tolerance in biofilms compared to planktonic cells (P < 0.001) which was not seen for A. odontolyticus. All strains except S. oralis induced an ATR after pre-exposure to pH 5.5 (P < 0.05). The presence of a salivary pellicle enhanced both acid tolerance development and ATR induction in S. gordonii biofilms (P < 0.05) but did not affect the other bacteria to the same extent. Conclusions These findings suggest that factors such as surface contact, the presence of a salivary pellicle and sensing of environmental pH can contribute to the development of high levels of acid tolerance amongst early colonizers in oral biofilms which may be important in the initiation of caries.

The involvement of ATPase activity in the acid tolerance ofLactobacillus rhamnosusstrain GG

2014 ◽  
Vol 67 (2) ◽  
pp. 229-236 ◽  
Author(s):  
Miseon Bang ◽  
Sangnam Oh ◽  
Kwang-Sei Lim ◽  
Younghoon Kim ◽  
Sejong Oh
Keyword(s):  
Atpase Activity ◽  
Acid Tolerance

scholarly journals A Novel Gene Involved in the Survival of Streptococcus mutans under Stress Conditions

2013 ◽  
Vol 80 (1) ◽  
pp. 97-103 ◽  
Author(s):  
Dan Li ◽  
Yukie Shibata ◽  
Toru Takeshita ◽  
Yoshihisa Yamashita
Keyword(s):  
Streptococcus Mutans ◽  
Streptococcus Pyogenes ◽  
Biofilm Formation ◽  
Acid Tolerance ◽  
Stress Conditions ◽  
Insertion Mutagenesis ◽  
Trna Modification ◽  
Content Type ◽  
Virulence Proteins ◽  
Random Insertion

ABSTRACTAStreptococcus mutansmutant defective in aciduricity was constructed by random-insertion mutagenesis. Sequence analysis of the mutant revealed a mutation ingidA, which is known to be involved in tRNA modification inStreptococcus pyogenes. Complementation ofgidAbyS. pyogenesgidArecovered the acid tolerance ofS. mutans. Although thegidA-inactivatedS. pyogenesmutant exhibited significantly reduced expression of multiple extracellular virulence proteins, theS. mutansmutant did not. On the other hand, thegidAmutant ofS. mutansshowed reduced ability to withstand exposure to other stress conditions (high osmotic pressure, high temperature, and bacitracin stress) besides an acidic environment. In addition, loss of GidA decreased the capacity for glucose-dependent biofilm formation by over 50%. This study revealed thatgidAplays critical roles in the survival ofS. mutansunder stress conditions, including lower pH.

THE EXCRETION OF LARGE VITAMIN C LOADS IN YOUNG AND ELDERLY SUBJECTS: AN ASCORBIC ACID TOLERANCE TEST

1988 ◽  
Vol 17 (1) ◽  
pp. 35-41 ◽  
Author(s):  
R. J. NEALE ◽  
H. LIM ◽  
JULIE TURNER ◽  
C. FREEMAN ◽  
J. R. KEMM
Keyword(s):  
Ascorbic Acid ◽  
Vitamin C ◽  
Acid Tolerance ◽  
Tolerance Test ◽  
Elderly Subjects ◽  
Young And Elderly Subjects

Exploring microbial community structure and their interrelationship in tomato Rhizosphere

2017 ◽  
Vol 12 ◽  
pp. 50-57
Author(s):  
Sangram Sinha ◽  
Keyword(s):  
Plant Growth ◽  
Microbial Diversity ◽  
Hot Spot ◽  
Acid Tolerance ◽  
Root Surface ◽  
Strong Correlations ◽  
Plant Microbe Interaction ◽  
Biochemical Characterisation ◽  
Promote Plant Growth ◽  
Phosphate Solubilizing

The Rhizosphere is the small zone surrounding plants' root surface is now considered as hot spot for microbial diversity and pivotal for plant-microbe interaction. The plant-microbe interaction is very vital for plant growth, productivity and stress tolerance. The present study attempted to explore the culturable microbial diversity in the tomato Rhizosphere from agricultural fields of Haripal block of West Bengal. The study found that the Rhizosphere is rich in gram-positive rods, and further biochemical characterisation predicted Bacillus cereus as the signature genus consisting of 26% of the total bacteria characterised in this study. Pearson’s correlation coefficient of different important adaptive characters of the bacterial population revealed strong correlations between salt tolerance, exo-polysaccharide (EPS) production, acid tolerance and phosphate solubilizing activity. These interactions may be crucial for Rhizosphere colonisation and overcoming hostile environment like salinity, drought, soil acidity and ultimately promote plant growth under diverse environmental stress.

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