Fluorine accounts for 0.3 g/kg of the Earth’s crust, being widely distributed in the environment as fluoride. The toxic effects of this anion in humans and other organisms have been known for a long time. Fluoride has been reported to alter several cellular processes although the mechanisms involved are largely unknown. Inorganic pyrophosphatases (PPases) are ubiquitous enzymes that hydrolyze inorganic pyrophosphate (PPi), a metabolite generated from ATP. In Saccharomyces cerevisiae, the enzyme responsible for PPi hydrolysis in the cytosol (IPP1) is strongly inhibited by fluoride in vitro. The essentiality of IPP1 for growth has been previously demonstrated using YPC3, a yeast mutant with conditional expression of the corresponding gene. Here, YPC3 was used to generate cells that tolerate high concentrations of fluoride by (a) the overexpression of IPP1 or its human ortholog, or (b) the substitution of IPP1 by the fluoride-insensitive PPase from Streptococcus mutans. The results obtained suggest that maintaining appropriate levels of PPase activity in the cytosol is essential for the adaptation of S. cerevisiae to high fluoride concentrations. The increase in fluoride tolerance allows YPC3 cells transformed with suitable plasmids to be selected on rich non-selective medium supplemented with this anion.

With the rapid expansion of aquaculture production, there has been a concomitant increase in fish diseases, generally combatted by the utilization of chemicals and antibiotics. However, their overuse leads to the emergence of drug-resistant microorganisms and the appearance of oxidative stress. Consequently, antibiotics contribute to a reduction in fish immune defense. In this work, eight marine bacteria were characterized using physiological, biochemical and microbiological tests, and were evaluated for their safety by studying their haemolytic and gelatinase activities. Then, we evaluated their ability to produce active biomolecules and tested their in vitro antibacterial activities against five bacterial pathogens that are highly prevalent in aquaculture. Moreover, we evaluated their antioxidant potential using DPPH, ABTS and ferric reducing power tests. The obtained results revealed that cell-free supernatants were effective, they exhibited good antioxidant and antibacterial activities. Their biomolecules showed good stability under different temperatures ranging from 60 to 121 degrees C and were found to be chemically composed of peptides, exopolysaccharides and polyphenols. Therefore, the secreted bioactive substances are of great biotechnological interest and constitute a promising eco-friendly alternative to antibiotics and chemical agents in the context of sustainable aquaculture.

A strain of the protozoan ciliate Tetrahymena thermophila adapted to increasing Pb(II) concentrations over two years has shown that one of the resistance mechanisms to this extreme metal stress is the lead biomineralization to chloropyromorphite, one of the most stable minerals in the earth's crust. Several techniques such as microanalysis coupled to transmission and scanning electron microscopy (X-Ray Energy Disperse Spectroscopy), fluorescence microscopy and X-ray power diffraction analysis have revealed the presence of chloropyromorphite as crystalline aggregates of nano-globular structure, together with the presence of other secondary lead minerals. This is the first time that the existence of this type of biomineralization in a ciliate protozoan is described. The Pb(II) bioremediation capacity of this strain has shown that it can remove >90 % of the toxic soluble lead from the medium. A quantitative proteomic analysis of this strain has revealed the main molecular-physiological elements involved in adaptation to Pb(II) stress: increased activity of proteolytic systems against lead proteotoxicity, occurrence of metallothioneins to immobilize Pb(II) ions, antioxidant enzymes to mitigate oxidative stress, and an intense vesicular trafficking presumably involved in the formation of vacuoles where pyromorphite accumulates and is subsequently excreted, together with an enhanced energy metabolism. As a conclusion, all these results have been compiled into an integrated model that could explain the eukaryotic cellular response to extreme lead stress.

Background:Antibiotic resistance is an important concern for the public health authorities at global level. It is detrimental to human and environmental ecosystems, thus, there is a big need for natural bioactive compounds. In this work, we aimed to find out biomolecules derived from marine bacteria that may constitute an alternative to antibiotics.Methods:We isolated and identified thirty one marine bacteria collected from deep ocean water in central coast of Safi city, Morocco. Then, we induced biomolecules production in six marine bacterial strains. The extracts were tested for their antibacterial activity against gram-negative and gram-positive bacteria such as Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 33592 and Listeria monocytogenes ATCC 19117. Furthermore, we partially analyzed the chemical composition of these biomolecules and evaluated their sensibility to different temperatures.Results:The six marine bacteria were able to produce molecules which inhibited the three pathogenic strains with high inhibition zones reaching 27 mm. These molecules were characterized by heat stability from 60 to 121°C relying on each strain.Conclusion:The produced molecules may offer a great potential to pharmaceutical industries as they may constitute an alternative to antibiotics that are becoming less effective due to the emergence of drugs resistance.

EDITORIAL article Front. Plant Sci., 26 March 2021Sec. Plant Metabolism and Chemodiversity https://doi.org/10.3389/fpls.2021.653416

Overexpression of membrane-bound K+-dependent H+-translocating inorganic pyrophosphatases (H+-PPases) from higher plants has been widely used to alleviate the sensitivity toward NaCl in these organisms, a strategy that had been previously tested inSaccharomyces cerevisiae. On the other hand, H+-PPases have been reported to functionally complement the yeast cytosolic soluble pyrophosphatase (IPP1). Here, the efficiency of the K+-dependent Na+-PPase from the archaeonMethanosarcina mazei(MVP) to functionally complement IPP1 has been compared to that of its H+-pumping counterpart fromArabidopsis thaliana(AVP1). Both membrane-bound integral PPases (mPPases) supported yeast growth equally well under normal conditions, however, cells expressing MVP grew significantly better than those expressing AVP1 under salt stress. The subcellular distribution of the heterologously-expressed mPPases was crucial in order to observe the phenotypes associated with the complementation.In vitrostudies showed that the PPase activity of MVP was less sensitive to Na(+)than that of AVP1. Consistently, when yeast cells expressing MVP were grown in the presence of NaCl only a marginal increase in their internal PPi levels was observed with respect to control cells. By contrast, yeast cells that expressed AVP1 had significantly higher levels of this metabolite under the same conditions. The H+-pumping activity of AVP1 was also markedly inhibited by Na+. Our results suggest that mPPases primarily act by hydrolysing the PPi generated in the cytosol when expressed in yeast, and that AVP1 is more susceptible to Na(+)inhibition than MVP bothin vivoandin vitro. Based on this experimental evidence, we propose Na+-PPases as biotechnological tools to generate salt-tolerant plants.

Bats are emblematic hosts of caves. These small flying mammals deserve special attention because their presence has a great economic and ecological impact; they introduce organic matter, the guano, in the ecosystem they live in. Indeed, “guano” (a Quechua word meaning “fertilizer”) is the accumulation of their fecal matter (excreta); its deposition can reach several meters. The composition of guano is influenced by the bat’s food. In addition to its role within the caves, the bat guano is exploited for various purposes; it is used as an effective fertilizer for the cultivation of plants because of having exceptionally high content of nitrogen, phosphate, and potassium and also for the improvement of detergents and other products of great value for humans. The bat guano hosts various classes of microorganisms (viruses, bacteria, algae, fungi, and protists), which are adapted to the cave environment. Since guano is highly acidic, these microorganisms can be considered as extremophiles. They produce functional organic compounds in extreme conditions that could be of interest not only in the drug industry but also in different biotechnological areas. Here, we review already available information on the ecological and economic effects of bats and their guano. We report their food preferences, foraging behaviors, and environmental impacts. Information on these aspects may be useful in finding a solution about protection and preservation of bat populations.

Overexpression of membrane-bound K+-dependent H+-translocating inorganic pyrophosphatases (H+-PPases) from higher plants has been widely used to alleviate the sensitivity toward NaCl in these organisms, a strategy that had been previously tested in Saccharomyces cerevisiae. On the other hand, H+-PPases have been reported to functionally complement the yeast cytosolic soluble pyrophosphatase (IPP1). Here, the efficiency of the K+-dependent Na+-PPase from the archaeon Methanosarcina mazei (MVP) to functionally complement IPP1 has been compared to that of its H+-pumping counterpart from Arabidopsis thaliana (AVP1). Both membrane-bound integral PPases (mPPases) supported yeast growth equally well under normal conditions, however, cells expressing MVP grew significantly better than those expressing AVP1 under salt stress. The subcellular distribution of the heterologously-expressed mPPases was crucial in order to observe the phenotypes associated with the complementation. In vitro studies showed that the PPase activity of MVP was less sensitive to Na+ than that of AVP1. Consistently, when yeast cells expressing MVP were grown in the presence of NaCl only a marginal increase in their internal PPi levels was observed with respect to control cells. By contrast, yeast cells that expressed AVP1 had significantly higher levels of this metabolite under the same conditions. The H+-pumping activity of AVP1 was also markedly inhibited by Na+. Our results suggest that mPPases primarily act by hydrolysing the PPi generated in the cytosol when expressed in yeast, and that AVP1 is more susceptible to Na+ inhibition than MVP both in vivo and in vitro. Based on this experimental evidence, we propose Na+-PPases as biotechnological tools to generate salt-tolerant plants.

The marine environment is characterized by a wide diversity of microorganisms among which marine bacteria. To insure their survival in hostile conditions where they face high competition with pathogenic microorganisms, they produce various kinds of bioactive molecules within biofilms with unique structural and functional features. As example: marine peptides which provide a broad spectrum of antimicrobial, antitumoral, antiviral and anti-inflammatory activities, in addition to marine exopolysaccharides showing antifouling and antifungal activities, immunomodulatory properties, emulsion stabilization capacity with other various potentials. Some biofilms have shown a beneficial role for aquaculture, among which enhancement of growth performance and improvement of water quality, while others are threatening not only aquaculture and maritime fields, but also medicine and food industry. Thus, marine bioactive compounds are promising preventing agents for the establishment and growth of fouling microorganisms, which may be useful in different fields in order to decrease economic losses and avoid foodborne illnesses. DOI: http://dx.doi.org/10.5281/zenodo.4384158

The microalgae Chlamydomonas reinhardtii and Chlorella sp. CCAP 211/84 were grown autotrophically and mixotrophically and their thermoluminescence emissions were recorded after excitation by 1, 2 or 3 xenon flashes or by continuous far-red light. An oscillation of the B band intensity according to the number of flashes was always observed, with a maximum after 2 flashes, accompanied by a downshift of the B band temperature maximum in mixotrophic compared to autotrophic grown cells, indicative of a dark stable pH gradient. Moreover, new flash-induced bands emerged in mixotrophic Chlamydomonas grown cells, at temperatures higher than that of the B band. In contrast to the afterglow band observed in higher plants, in Chlamydomonas these bands were not inducible by far-red light, were fully suppressed by 2 μM antimycin A, and peaked at different temperatures depending on the flash

Inorganic pyrophosphate (PPi) is an abundant by-product of cellular metabolism. PPi-producing reactions take place in the nucleus concurrently with reactions that use PPi as a substrate. Saccharomyces cerevisiae possesses two soluble pyrophosphatases (sPPases): Ipp1p, an essential and allegedly cytosolic protein, and Ipp2p, a mitochondrial isoenzyme. However, no sPPase has yet been unambiguously described in the nucleus. In vivo studies with fluorescent fusions together with activity and immunodetection analyses demonstrated that Ipp1p is a nucleocytoplasmic protein. Mutagenesis analysis showed that this sPPase possesses a nuclear localization signal which participates in its nuclear targeting. Enforced nucleocytoplasmic targeting by fusion to heterologous nuclear import and export signals caused changes in polypeptide abundance and activity levels, indicating that Ipp1p is less stable in the nucleus that in the cytoplasm. Low nuclear levels of this sPPase are physiologically relevant and may be related to its catalytic activity, since cells expressing a functional nuclear-targeted chimaera showed impaired growth and reduced chronological lifespan, while a nuclear-targeted catalytically inactive protein was not degraded and accumulated in the nucleus. Moreover, nuclear proteasome inhibition stabilized Ipp1p whereas nuclear targeting promoted its ubiquitination and interaction with Ubp3p, a component of the ubiquitin-proteasome system. Overall, our results indicate that Ipp1p is nucleocytoplasmic, that its stability depends on its subcellular localization and that sPPase catalytic competence drives its nuclear degradation through the ubiquitin-proteasome system. This suggests a new scenario for PPi homeostasis where both nucleocytoplasmic transport and nuclear proteasome degradation of the sPPase should contribute to control nuclear levels of this ubiquitous metabolite.

Staphylococcus aureus is one of the main pathogenic agents responsible for nosocomial and community-acquired bacterial infections. The pathogenicity of this Gram-positive bacterium is ensured by its different adhesion factors. Collagen and the extracellular glycoprotein adhesin are among the Staphylococcus most important virulence factors. It has been shown that most of the S. aureus strains carry the ica operon, responsible for biofilm production. However, the coexpression of the icaA and the icaD genes is necessary for complete biofilm synthesis. The aim of our study was to study a collection of 15 clinical strains of S. aureus from different sources for the presence of can and icaD genes coding intercellular adhesion proteins. We also intended to estimate the strains’ ability to form biofilms by the red Cong method and to test the adhesion ability of S. aureus to the ciliated protist Tetrahymena pyriformis, which we used as a novel cellular adhesion model. Finally, we checked the adhesion’s inhibition capacity of some plants extracts. The molecular detection of adhesion genes revealed that 80% of strains are cna positive, and 73% are icaD positive. Qualitative biofilm production of S. aureus revealed that 66.6% of strains were slime producers. The adhesion test revealed that 20% of strains are strongly adhering to T. pyriformis and that the Clematis cirrhosa extract has an anti-adhering effect of S. aureus to the ciliate T. pyriformis.

Phosphorus is one of the bioelements most needed as a compound cell by living organisms. Phosphorus is involved in several pathologies: in human with bone and kidney diseases, in mammals with metabolism disorder (glucose, insulin···), in microorganisms whose phosphorus is involved in cell growth. Phosphorus has various forms including pyrophosphate, a by-product of multiple pathways of biosynthesis. Enzymes that hydrolyze pyrophosphate are called inorganic pyrophosphatases (PPases). Two major types of inorganic pyrophosphatases are distinguished: the soluble pyrophosphatases (sPPases) and the membrane pyrophosphatases (mPPases or H+/Na+-PPases). They play a key role in the control of intracellular inorganic pyrophosphate level and produce an important ions gradient (H+ or Na+) to the cells. In this work, we primarily focused on the physiological study in a phosphate-poor medium of two models Tetrahymena thermophile and Tetrahymena pyriformis, following the mobility, the growth and the morphology of cells. Secondly, we evaluated the enzymatic activity of soluble and membrane pyrophosphatases in both species grown in the same complex medium. A decrease of cell growth is correlated with unusual morphologies and different mobility in the stress medium. The measurement of soluble and membrane inorganic pyrophosphatases activities also shows a decrease which illustrates the lack of phosphate found in the stress medium. Deficiency of phosphate is a limiting factor for protozoan growth. These results indicate that Tetrahymena can be used as a model of cellular stress and consists of a target to study inorganic pyrophosphatases for a better understanding of phosphate cycle in higher organisms.

To investigate biological control mains against phytopathogenic agent Pseudomonas syringae pv. tomato DC3000, responsible for bacterial speck, tests on the antibacterial activity of six essential oils were carried out. The essential oils, obtained by hydro distillation, was analyzed by gas chromatography (GC). The determination of the antibacterial activity of the essential oils carried out in-vitro using the well diffusion, micro atmosphere methods and the determination of MIC and CMB. Only essential oils of Cedrus atlantica had a negative activity against the bacterial strain. However, the overall results of this study suggested that Mintha pulegium, Thym vulgaris, Eucalyptus globulus essential oils had potential as a bio-pesticide for the control of bacterial speck disease of tomato.

Inorganic pyrophosphatases are enzymes that catalyze the hydrolysis of inorganic pyrophosphate to orthophosphate. These enzymes are divided into two groups: the soluble pyrophosphatases and the membrane pyrophosphatases. They vary in structure and each has a determined catalysis mechanism. Soluble pyrophosphatases are ubiquitous enzymes and play a key role in regulating the rate of pyrophosphate and balance in this sense, the biosynthetic reactions. Membrane pyrophosphatases are ion pumps, producing a proton or sodium gradient, and provide critical energy reserves to organisms, especially during stress conditions. Several studies have shown that these enzymes are involved in numerous disorders (diseases, fault cell growth···). However they are potential targets for the development of agents against parasites. This article consists of a description of the different types, structures, catalytic properties of inorganic pyrophosphatases and their involvement in cellular metabolism.

Phosphorusis one of the bioelements most needed as a compound cell by living organisms.Phosphorus is involved in several pathologies: in human with bone and kidneydiseases, in mammals with metabolism disorder (glucose, insulin···), inmicroorganisms whose phosphorus is involved in cell growth. Phosphorus has various forms includingpyrophosphate, a by-product of multiple pathways of biosynthesis. Enzymes thathydrolyze pyrophosphate are called inorganic pyrophosphatases (PPases). Twomajor types of inorganic pyrophosphatases are distinguished: the solublepyrophosphatases (sPPases) and the membrane pyrophosphatases (mPPases or H+/Na+-PPases).They play a key role in the control of intracellular inorganic pyrophosphatelevel and produce an important ions gradient (H+ or Na+)to the cells. In this work, we primarily focused on the physiological study ina phosphate-poor medium of two models Tetrahymena thermophile and Tetrahymena pyriformis,following the mobility, the growth and the morphology of cells. Secondly, weevaluated the enzymatic activity of soluble and membrane pyrophosphatases inboth species grown in the same complex medium. A decrease of cell growth iscorrelated with unusual morphologies and different mobility in the stressmedium. The measurement of soluble and membrane inorganic pyrophosphatasesactivities also shows a decrease which illustrates the lack of phosphate foundin the stress medium. Deficiency of phosphate is a limiting factor forprotozoan growth. These results indicate that Tetrahymena can be used as a model of cellular stressand consists of a target to studyinorganic pyrophosphatases for a better understanding of phosphate cycle inhigher organisms.