stationary growth phase
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mSphere ◽  
2022 ◽  
Author(s):  
Wiep Klaas Smits ◽  
Yassene Mohammed ◽  
Arnoud H. de Ru ◽  
Valentina Cordo' ◽  
Annemieke H. Friggen ◽  
...  

In this paper, we present a comprehensive analysis of protein phosphorylation in the Gram-positive enteropathogen Clostridioides difficile . To date, only limited evidence on the role of phosphorylation in the regulation of this organism has been published; the current study is expected to form the basis for research on this posttranslational modification in C. difficile .  


2022 ◽  
Vol 12 ◽  
Author(s):  
Troels Ronco ◽  
Line H. Kappel ◽  
Maria F. Aragao ◽  
Niccolo Biagi ◽  
Søren Svenningsen ◽  
...  

Multidrug-resistant pathogens constitute a serious global issue and, therefore, novel antimicrobials with new modes of action are urgently needed. Here, we investigated the effect of a phenothiazine derivative (JBC 1847) with high antimicrobial activity on Staphylococcus aureus, using a wide range of in vitro assays, flow cytometry, and RNA transcriptomics. The flow cytometry results showed that JBC 1847 rapidly caused depolarization of the cell membrane, while the macromolecule synthesis inhibition assay showed that the synthesis rates of DNA, RNA, cell wall, and proteins, respectively, were strongly decreased. Transcriptome analysis of S. aureus exposed to sub-inhibitory concentrations of JBC 1847 identified a total of 78 downregulated genes, whereas not a single gene was found to be significantly upregulated. Most importantly, there was downregulation of genes involved in adenosintrifosfat (ATP)-dependent pathways, including histidine biosynthesis, which is likely to correlate with the observed lower level of intracellular ATP in JBC 1847–treated cells. Furthermore, we showed that JBC 1847 is bactericidal against both exponentially growing cells and cells in a stationary growth phase. In conclusion, our results showed that the antimicrobial properties of JBC 1847 were primarily caused by depolarization of the cell membrane resulting in dissipation of the proton motive force (PMF), whereby many essential bacterial processes are affected. JBC 1847 resulted in lowered intracellular levels of ATP followed by decreased macromolecule synthesis rate and downregulation of genes essential for the amino acid metabolism in S. aureus. Bacterial compensatory mechanisms for this proposed multi-target activity of JBC 1847 seem to be limited based on the observed very low frequency of resistance toward the compound.


2021 ◽  
Author(s):  
Lyudmila Galaktionova ◽  
Alexey Nikolaevich Sizentsov ◽  
Olga Konstantinovna Davydova ◽  
Hike Nikolaevich Nikiyan ◽  
Yaroslav Alekseevich Sizentsov

The article presents data on the physicochemical and metabolically dependent mechanisms of detoxification by microorganisms of heavy metals that enter the environment during anthropogenic pollution. The taxonomic and physiological-biochemical diversity of microorganisms capable of neutralizing toxicants has been demonstrated. In the experimental part of the study, the combination of the methods used made it possible to fully assess the degree of toxicity and the effect of lead cations on the growth of bacteria of the genus Bacillus in a model experiment. Thus, the use of atomic absorption spectrophotometry and atomic force microscopy gave an idea of the level of biosorption of a given xenobiotic element from a substrate with localization of inactive forms of lead. The data obtained indicate the presence of an inhibitory effect of Pb (NO3) 2 and Pb (CH3COO) 2 in concentrations from 1 mM to 0.063 mM about the test organisms under study. The presence of cations with a nutrient substrate gives a false-positive idea of the degree of influence of lead on the growth of the studied microorganisms, since an increase in optical density in test samples is due to high sorption characteristics and, as a consequence, is characterized by an increase in relative optical density. An assessment of the detoxification mechanisms, which is expressed by active bioaccumulation of lead on the surface elements of the microbial cell up to 65% at the point of entering the stationary growth phase, indicates the promising use of representatives of this group of microorganisms as microbial bioremediation and correctors of excess content of this element in the body or ecosystem as a whole.


Author(s):  
yaqiu Zhang ◽  
Yiqing Deng ◽  
Juan Feng ◽  
Jianmei Hu ◽  
Haoxiang Chen ◽  
...  

In this study, an in-frame deletion of the luxS gene was constructed to reveal the role of LuxS in the physiology and virulence of V. harveyi. The statistical analysis showed no significant differences in the growth ability, biofilm formation, antibiotic susceptibility, virulence by intraperitoneal injection, and the ability of V. harveyi to colonize the spleen and liver of the pearl gentian grouper between the wild-type (WT) and the luxS mutant. However, the deletion of luxS decreased the secretion of extracellular protease, while increased the ability of swimming and swarming. Simultaneously, a luxS-deleted mutant showed overproduction of lateral flagella, and an intact luxS complemented the defect. Since motility is flagella dependent, 16 of V. harveyi flagella biogenesis related genes were selected for further analysis. Based on quantitative real-time reverse transcription-PCR (qRT-PCR), the expression levels of these genes, including the polar flagella genes flaB, flhA, flhF, flhB, flhF, fliS, and flrA and the lateral flagella genes flgA, flgB, fliE, fliF, lafA, lafK, and motY, were significantly up-regulated in the ΔluxS: pMMB207 (ΔluxS+) strain as compared with the V. harveyi 345: pMMB207 (WT+) and C-ΔluxS strains during the early, mid-exponential, and stationary growth phase.


2021 ◽  
Vol 14 (11) ◽  
pp. 1182
Author(s):  
Vladimir Vimberg ◽  
Leona Zieglerova ◽  
Aninda Mazumdar ◽  
Zsolt Szűcs ◽  
Aniko Borbás ◽  
...  

The increase in antibiotic resistance among Gram-positive bacteria underscores the urgent need to develop new antibiotics. New antibiotics should target actively growing susceptible bacteria that are resistant to clinically accepted antibiotics including bacteria that are not growing or are protected in a biofilm environment. In this paper, we compare the in vitro activities of two new semisynthetic glycopeptide antibiotics, MA79 and ERJ390, with two clinically used glycopeptide antibiotics—vancomycin and teicoplanin. The new antibiotics effectively killed not only exponentially growing cells of Staphylococcus aureus, but also cells in the stationary growth phase and biofilm.


2021 ◽  
Author(s):  
Antoine Cossa ◽  
Sylvain Trépout ◽  
Frank Wien ◽  
Etienne Le Brun ◽  
Florian Turbant ◽  
...  

Bacterial chromosomic DNA is packed within a membrane-less structure, the nucleoid, thanks to proteins called Nucleoid Associated Proteins (NAPs). The NAP composition of the nucleoid varies during the bacterial life cycle and is growth phase-dependent. Among these NAPs, Hfq is one of the most intriguing as it plays both direct and indirect roles on DNA structure. Indeed, Hfq is best known to mediate post-transcriptional regulation by using small noncoding RNA (sRNA). Although Hfq presence in the nucleoid has been demonstrated for years, its precise role is still unclear. Recently, it has been shown in vitro that Hfq belongs to the bridging family of NAPs. Its bridging mechanism relies on the formation of the amyloid-like structure of Hfq C-terminal region. Here, using cryo soft X-ray tomography imaging of native unlabelled cells and using a semi-automatic analysis and segmentation procedure, we show that Hfq significantly remodels the Escherichia coli nucleoid, especially during the stationary growth phase. Hfq influences both nucleoid volume and absorbance. Hfq cumulates direct effects and indirect effects due to sRNA-based regulation of other NAPs. Taken together, our findings reveal a new role for this protein in nucleoid remodelling that may serve in response to stress conditions and in adapting to changing environments. This implies that Hfq regulates nucleoid compaction directly via its interaction with DNA, but also at the post-transcriptional level via its interaction with RNA.


2021 ◽  
Vol 11 (20) ◽  
pp. 9573
Author(s):  
Natalia Kujawska ◽  
Szymon Talbierz ◽  
Marcin Dębowski ◽  
Joanna Kazimierowicz ◽  
Marcin Zieliński

The study aimed to determine the effectiveness of docosahexaenoic acid (DHA) production by Schizochytrium sp. biomass fed with waste glycerol depending on the concentration of extracellular polymeric substances (EPS) in the culture medium and medium aeration effectiveness. The microalgae from the genus Schizochytrium sp. were proved to be capable of producing EPS composed of glucose, galactose, mannose, fucose, and xylose. The highest EPS concentration, reaching 8.73 ± 0.09 g/dm3, was determined at the stationary growth phase. A high EPS concentration caused culture medium viscosity to increase, contributing to diminished oxygen availability for cells, lower culture effectiveness, and reduced waste glycerol conversion to DHA. The Schizochytrium sp. culture variant found optimal in terms of the obtained technological effects and operating costs was performed at the volumetric oxygen mass transfer coefficient of kLa = 600 1/h, which enabled obtaining dry cell weight (DCW) of 147.89 ± 4.77 g/dm3, lipid concentration of 69.44 ± 0.76 g/dm3, and DHA concentration in the biomass reaching 29.44 ± 0.36 g/dm3. The effectiveness of waste glycerol consumption in this variant reached 3.76 ± 0.31 g/dm3·h and 3.16 ± 0.22 g/gDCW.


2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 348-349
Author(s):  
Nadezhda Terekhova ◽  
Lyudmila Galaktionova ◽  
Alexey Sizentsov ◽  
Olga Davydova ◽  
Hike Nikiyan

Abstract The research was supported by the Ministry of Science and Higher Education in accordance with the state assignment for Ural State Mining University No. 0833-2020-0008 ‘Development and environmental and economic substantiation of the technology for reclamation of land disturbed by the mining and metallurgical complex based on reclamation materials and fertilizers of a new type’. We obtain the scientific results by using funds of the Center for the collective use of scientific equipment of the Federal Scientific Center of biological systems and agricultural technologies of RAS as well (No Ross RU.0001.21 PF59, the Unified Russian Register of Centers for Collective Use - http://www.ckp-rf.ru/ckp/77384).The search for natural bioremediators to restore crop and grazing lands in conditions of the increased anthropogenic load is a relevant and promisingly significant area of research. Thus, we were tasked to assess the prospect of using the physiological and adaptive characteristics of microorganisms of the genus Bacillus as an active biosorbent of movable forms of lead from the substrate on the in vitro model.Soil isolates of microorganisms of the genus Bacillus extracted from samples from areas with increased lead levels were used to achieve our aim. Pb(NO3)2 solutions in the concentration range from 1 to 0.063M were used as the factor regulating the growth. Methods used in the work were: the method of agar basins, the nephelometric method, atomic-absorption spectroscopy, and atomic force microscopy. B. subtilis and B. cereus were isolated from soil samples. The maximum resistance to different concentrations of Pb(NO3)2 was revealed for B. subtilis. The presence of lead cations in the nutrient substrate significantly increased the population density to 26.0%. At the same time, the percentage of lead sorption in the initial stage of the stationary growth phase was 65.3% with the maximum localization on the surface structures of the cell membrane.


2021 ◽  
pp. 103885
Author(s):  
Katarina Novović ◽  
Milka Malešević ◽  
Lazar Gardijan ◽  
Milan Kojić ◽  
Branko Jovčić

Botany ◽  
2021 ◽  
Author(s):  
Veronica Ambrosini ◽  
Mohammad Issawi ◽  
Catherine Riou

Tobacco cell suspension (TBY-2) is known to produce starch when cultured in medium supplemented with cytokinin or in hormone-free medium. Unexpectedly, TBY-2 cells, continuously cultivated on auxin alone, were also able to accumulate starch at the beginning of stationary growth phase with a yield of 9.22 ± 0.68 percent. This starch production was strongly correlated with a 25-fold increase in starch synthase activity. Moreover, this TBY-2 line was able to produce an amylopectin-rich starch with a ratio amylopectin over amylose of 2.7 which also linked to typical small granules (size around 1.4 µm). According to our preliminary results, this plant cell suspension could produce a low-cost amylopectin rich starch needed in the food industry for production of edible film or bioplastic without impacts from climate or season changes.


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