The nutritional environment is sufficient to select coexisting biofilm and quorum-sensing mutants of Pseudomonas aeruginosa

The evolution of bacterial populations during infections can be influenced by various factors including available nutrients, the immune system, and competing microbes, rendering it difficult to identify the specific forces that select on evolved traits. The genomes of Pseudomonas aeruginosa isolated from the airway of patients with cystic fibrosis (CF), for example, have revealed commonly mutated genes, but which phenotypes led to their prevalence is often uncertain. Here, we focus on effects of nutritional components of the CF airway on genetic adaptations by P. aeruginosa grown in either well-mixed (planktonic) or biofilm-associated conditions. After only 80 generations of experimental evolution in a simple medium with glucose, lactate, and amino acids, all planktonic populations diversified into lineages with mutated genes common to CF infections: morA , encoding a regulator of biofilm formation, or lasR , encoding a quorum sensing regulator that modulates the expression of virulence factors. Although mutated quorum sensing is often thought to be selected in vivo due to altered virulence phenotypes or social cheating, isolates with lasR mutations demonstrated increased fitness when grown alone and outcompeted the ancestral PA14 strain. Nonsynonymous SNPs in morA increased fitness in a nutrient concentration-dependent manner during planktonic growth and surprisingly also increased biofilm production. Populations propagated in biofilm conditions also acquired mutations in loci associated with chronic infections, including lasR and cyclic-di-GMP regulators roeA and wspF . These findings demonstrate that nutrient conditions and biofilm selection are sufficient to select mutants with problematic clinical phenotypes including increased biofilm and altered quorum sensing. Importance Pseudomonas aeruginosa produces dangerous chronic infections that are known for their rapid diversification and recalcitrance to treatment. We performed evolution experiments to identify adaptations selected by two specific aspects of the CF respiratory environment: nutrient levels and surface attachment. Propagation of P. aeruginosa in nutrients present within the CF airway was sufficient to drive diversification into subpopulations with identical mutations in regulators of biofilm and quorum sensing to those arising during infection. Thus, the adaptation of opportunistic pathogens to nutrients found in the host may select mutants with phenotypes that complicate treatment and clearance of infection.

FDH Knockout and TsFDH Transformation Led to Enhanced Growth Rate of Escherichia Coli

Background:Increased Atmospheric CO2 to over 400 ppm has prompted global climate irregularities. Reducing the released CO2 from biotechnological processes could remediate these phenomena. In this study, we sought to find a solution to reduce the amount of CO2 in the process of growth and reproduction by preventing the conversion of formic acid into CO2.Results:The (bio)chemical conversion of formic acid to CO2 is a key reaction. Therefore, we compared the growth of BL21, being a subfamily of K12, alongside two strains in which two different genes related to the formate metabolism were deleted, in complex and simple media. Experimental results were entirely consistent with metabolic predictions. Subsequently, the knockout bacteria grew more efficiently than BL21. Interestingly, TsFDH, a formate dehydrogenase with the tendency of converting CO2 to formate, increased the growth of all strains compared with cells without the TsFDH. Most mutants grew in a simple medium containing glycerol, which showed that glycerol is the preferred carbon source compared to glucose for the growth of E. coli. Conclusion:These results explain the reasons for the inconsistency of predictions in previous metabolic models that declared glycerol as a suitable carbon source for the growth of E. coli but failed to achieve it in practice. To conduct a more mechanistic evaluation of our observations, RNA sequencing data analysis was conducted on an E. coli RNA-seq dataset. The gene expression correlation outcome revealed the increased expression levels of several genes related to protein biosynthesis and glycerol degradation as a possible explanation of our observations.

The nutritional environment is sufficient to select coexisting biofilm and quorum-sensing mutants of Pseudomonas aeruginosa

The evolution of bacterial populations during infections can be influenced by various factors including available nutrients, the immune system, and competing microbes, rendering it difficult to identify the specific forces that select on evolved traits. The genomes of Pseudomonas aeruginosa isolated from the airway of patients with cystic fibrosis (CF), for example, have revealed commonly mutated genes, but which phenotypes led to their prevalence is often uncertain. Here, we focus on effects of nutritional components of the CF airway on genetic adaptations by P. aeruginosa grown in either well-mixed (planktonic) or biofilm-associated conditions. After only 80 generations of experimental evolution in a simple medium with glucose, lactate, and amino acids, all planktonic populations diversified into lineages with mutated genes common to CF infections: morA, encoding a regulator of biofilm formation, or lasR, encoding a quorum sensing regulator that modulates the expression of virulence factors. Although mutated quorum sensing is often thought to be selected in vivo due to altered virulence phenotypes or social cheating, isolates with lasR mutations demonstrated increased fitness when grown alone and outcompeted the ancestral PA14 strain. Nonsynonymous SNPs in morA increased fitness in a nutrient concentration-dependent manner during planktonic growth and surprisingly also increased biofilm production. Populations propagated in biofilm conditions also acquired mutations in loci associated with chronic infections, including lasR and cyclic-di-GMP regulators roeA and wspF. These findings demonstrate that nutrient conditions and biofilm selection are alone sufficient to select mutants with problematic clinical phenotypes including increased biofilm and altered quorum sensing.

Workshop Training for Tooth Color Selection to Meet the Need Based and Competency Based Education in Dentistry

Background and Objectives: Professional qualification-based dentist training plays an important role in providing the health services needed by the community. One of the most important steps in dentistry is choosing the color and matching the color of the tooth with the restoration. Color selection training in the curriculum of Iranian dental schools is provided to students as implicit training in some related courses such as restorations and prosthetics, and there is no separate practical unit for students to learn and practice more. The purpose of this study is to investigate the role of workshop training in the quality of tooth color selection by final year students of Tabriz Dental School in the academic year2019-2020. Material and Methods: In a quasi-experimeایntal study; Final year students of Tabriz Dental School entered the study. Students were randomly divided into experimental and control groups. In the experimental group, after selecting the primary color, through the workshop training strategy, color selection by Vitapan system in the right maxilla incisor 3 patients were taught simple, medium and complex method of workshop training and one week after training the correct color selection It was reviewed by these students. In the control group, color selection was done by students in exactly the same conditions as the case group who had received routine training. The data obtained from the study were analyzed using descriptive statistical methods (frequency-percentage) and Fisher's Exact test and statistical software SPSS.16. Results: In all three groups of simple, medium and complex patients, the quality of color selection in the intervention group was improved, which was significantly different from a dental point of view; however, there was no statistically significant difference between the intervention and control groups in all three groups of patients. Also, the effect of training in choosing complex colors was more significant. Conclusion: The results of the present study showed that workshop training had a positive effect on the color choice of dental students. Because dentistry is a procedure-based discipline and not all procedures are seen in the training curriculum. The dental professor can choose some procedures based on the pervasive need and teach in one workshop day. On the other hand, workshop training can be an proper educational strategy based on adult learning that learners show a lot of desire to learn according to their job needs.

NEW VARIETY OF FIELD PEAS VYATICH

The article provides a brief economic and biological characteristics of a new variety of field peas Vyatich, transferred to the State variety testing in 2020. The variety was created by individual selection from the hybrid population of Kazanets x K-3283. According to morphological characteristics, Vyatich belongs to the varieties of the mustachioed morphotype. The stem is simple, medium length (45-120 cm), purple flowers, inflorescence-2-3 axillary brush flowers. Seeds are greenish-brown with a purple speck, medium-small with a fused peduncle (weight of 1000 seeds 140-170 g). The variety is medium-ripened, Matures 2 days later than the standard. According to the competitive variety testing for 2016-2019, the average yield of Vyatich grain was 3.65 t / ha, green mass-32.2 t / ha, dry mass-5.67 t / ha, exceeding the ryabchik standard by 58.7%, 33.0% and 43.9%, respectively. According to the results of structural analysis, the Vyatich variety has an advantage in the number of beans and grains per plant (0.9 and 4.1 PCs higher than the standard). accordingly), the number of beans on the fruit node (more than 0.3 PCs.), the weight of seeds from the plant (more than 0.4 g). The average height of the new plant variety is 79 cm, and it is very resistant to lodging. The protein content in the grain averaged 20.6%, in the dry vegetative mass-14.2%. The gross yield of crude protein was 743 kg / ha for grain and 783 kg / ha for green mass, which is 60% and 54% higher than the standard, respectively. The Vyatich variety is recommended to be cultivated in single-species crops and used for forage purposes.

The Effect of Preincubation Time and Myo-inositol Supplementation on the Quality of Mouse MII Oocytes

Background: It is demonstrated that optimal preincubation time improves oocyte quality, fertilization potential and developmental rate. This study aimed to evaluate the effect of preincubation time in the simple and myo-inositol supplemented medium on the oocyte quality regarding oxidative stress and mitochondrial alteration. Methods: Cumulus oocyte complexes (COCs) retrieved from superovulated NMRI mice were divided in groups of 0, 4 and 8 hr preincubation time in the simple and 20 mmol/L myo-inositol supplemented media. Intracellular reactive oxygen species (H2O2), glutathione (GSH), mitochondrial membrane potential (MMP), ATP content, and mitochondrial amount were measured and analyzed in experimental groups. One-way ANOVA and Kruskal-Wallis were respectively used for parametric and nonparametric variables. Statistical significance was defined as p<0.05. Results: In comparison to control group, variables including ROS, GSH, mitochondrial amount, fertilization and developmental rates were significantly changed after 4 hr of preincubation in the simple medium, while MMP decreased following 8 hr of preincubation in the simple medium (p˂0.001). Preincubation of oocytes up to 8 hr in the simple medium could not decrease ATP content. For both 4 and 8 hr preincubation times, myo-inositole could decrease H2O2 and increase GSH and MMP levels and consequently could improve fertilization rate compared to oocytes preincubated in the simple culture. Conclusion: It seems that 4 hr or more preincubation time can decrease the oocyte quality and lead to reduced oocyte fertilization and developmental potential. Howevere, myo-inositol may prevent oocyte quality reduction and improve fertilization potential in comparision to the equivalent simple groups.

Waste Conversion into a Sweetener—Development of an Innovative Strategy for Erythritol Production by Yarrowia lipolytica

The study proposed the innovative low-cost strategy for erythritol production by Yarrowia lipolytica through developing a simple medium based on industrial waste by-products and a natural method for culture broth purification. Results obtained proved that corn steep liquor might successfully replace traditional sources of nitrogen and other nutrients without compromising activities of the enzymes responsible for erythritol production and its production level. As a consequence, a production process was performed where Y. lipolytica A-6 was able to produce 108.0 g/L of erythritol, with a production rate of 1.04 g/Lh and a yield of 0.45 g/g of the medium containing exclusively 220 g/L of crude glycerol derived from biodiesel production and 40 g/L of corn steep liquor. Moreover, a comparable concentration of erythritol (108.1 g/L) was obtained when a part of crude glycerol was exchanged for the crude fraction of fatty acids in the two-steps process. Next, the collected post-fermentation broths were used in the culture with Y. lipolytica Wratislavia K1 for natural purification. The process resulted in a high increase of erythritol selectivity from 72% to 97% and in the production of 22.0 g/L of biomass with 40.4% protein content, which enables its use as an attractive animal feedstuff.