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Current Research in Microbial Sciences Dec 2021Pro-Pro-endopeptidases (PPEP, EC 3.4.24.89) are secreted, zinc metalloproteases that have the unusual capacity to cleave a peptide bond between two prolines, a bond that... (Review)
Review
Pro-Pro-endopeptidases (PPEP, EC 3.4.24.89) are secreted, zinc metalloproteases that have the unusual capacity to cleave a peptide bond between two prolines, a bond that is generally less sensitive to proteolytic cleavage. Two well studied members of the family are PPEP-1 and PPEP-2, produced by a human pathogen, and , a bee secondary invader, respectively. Both proteases seem to be involved in mediating bacterial adhesion by cleaving cell surface anchor proteins on the bacterium itself. By using basic alignment and phylogenetic profiling analysis, this work shows that the complete family of proteins that contain a PPEP domain includes proteins from more than 130 species spread over 9 genera. These analyses also suggest that the PPEP domain spread through horizontal gene transfer events between species within the Firmicutes' classes Bacilli and Clostridia. Bacterial species containing PPEP homologs are found in diverse habitats, varying from human pathogens and gut microbiota to free-living bacteria, which were isolated from various environments, including extreme conditions such as hot springs, desert soil and salt lakes. The phylogenetic tree reveals the relationships between family members and suggests that smaller subgroups could share cleavage specificity, substrates and functional similarity. Except for PPEP-1 and PPEP-2, no cleavage specificity, specific physiological target, or function has been assigned for any of the other PPEP-family members. Some PPEP proteins have acquired additional domains that recognize and bind noncovalently to various elements of the bacterial peptidoglycan cell-wall, anchoring these PPEPs. Secreted or anchored to the cell-wall surface PPEP proteins seem to perform various functions.
PubMed: 34841315
DOI: 10.1016/j.crmicr.2021.100024 -
Biomolecules Nov 2021Ketalpyruvyltransferases belong to a widespread but little investigated class of enzymes, which utilise phosphoenolpyruvate (PEP) for the pyruvylation of saccharides....
Ketalpyruvyltransferases belong to a widespread but little investigated class of enzymes, which utilise phosphoenolpyruvate (PEP) for the pyruvylation of saccharides. Pyruvylated saccharides play pivotal biological roles, ranging from protein binding to virulence. Limiting factors for the characterisation of ketalpyruvyltransferases are the availability of cognate acceptor substrates and a straightforward enzyme assay. We report on a fast ketalpyruvyltransferase assay based on the colorimetric detection of phosphate released during pyruvyltransfer from PEP onto the acceptor via complexation with Malachite Green and molybdate. To optimise the assay for the model 4,6-ketalpyruvyl::ManNAc-transferase CsaB from , a β-d-ManNAc-α-d-GlcNAc-diphosphoryl-11-phenoxyundecyl acceptor mimicking an intermediate of the bacterium's cell wall glycopolymer biosynthesis pathway, upon which CsaB is naturally active, was produced chemo-enzymatically and used together with recombinant CsaB. Optimal assay conditions were 5 min reaction time at 37 °C and pH 7.5, followed by colour development for 1 h at 37 °C and measurement of absorbance at 620 nm. The structure of the generated pyruvylated product was confirmed by NMR spectroscopy. Using the established assay, the first kinetic constants of a 4,6-ketalpyuvyl::ManNAc-transferase could be determined; upon variation of the acceptor and PEP concentrations, a of 19.50 ± 3.50 µM and of 0.21 ± 0.01 s as well as a of 258 ± 38 µM and a of 0.15 ± 0.01 s were revealed. CsaB was inactive on synthetic NP-β-d-ManNAc and β-d-ManNAc-β-d-GlcNAc-1-Me, supporting the necessity of a complex acceptor substrate.
Topics: Catalysis; Hexosamines; Paenibacillus; Phosphates; Phosphoenolpyruvate
PubMed: 34827730
DOI: 10.3390/biom11111732 -
Toxins Oct 2021Food bio-preservatives are requested as substituents of chemical pesticides in food. The aim of this study was to carry out a screening of twenty biocontrol agents...
Food bio-preservatives are requested as substituents of chemical pesticides in food. The aim of this study was to carry out a screening of twenty biocontrol agents (BCAs) for their potential fungicidal activity in vitro. Twenty BCAs were tested against ten pathogenic fungi. Some of the cell-free supernatants (CFS) tested showed in vitro antifungal activity versus pathogenic fungi. The highest fungicidal activity was observed in the fermented CFS of CECT 375, CECT 493, and CECT 850, which showed a minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) values of 125 and 250 g/L, respectively. The compounds responsible for the antifungal activity, such as organic and phenolic acids, were determined. Lactic acid, acetic acid, benzoic acid, and phenyllactic acid among others can be related to antifungal activity. HPLC-MS/MS analysis showed a reduction of ochratoxin A (OTA) and aflatoxin B (AFB) up to 26% ( CECT 2) and 55% ( CECT 155), respectively. The present study prompts that metabolism products of BCAs are propitious for the bioconservation of food, due to their ability to reduce the proliferation of mycotoxigenic fungi and mycotoxins production.
Topics: Aflatoxin B1; Antifungal Agents; Bacillus amyloliquefaciens; Cell-Free System; Fungicides, Industrial; In Vitro Techniques; Ochratoxins; Paenibacillus; Pantoea; Pest Control, Biological; Poisons
PubMed: 34822536
DOI: 10.3390/toxins13110752 -
Frontiers in Plant Science 2021The sustainable development of agriculture can be stimulated by the great market availability of bio-inputs, including phosphate-solubilizing microbial strains. However,...
The sustainable development of agriculture can be stimulated by the great market availability of bio-inputs, including phosphate-solubilizing microbial strains. However, these strains are currently selected using imprecise and questionable solubilization methodologies in solid or liquid media. We hypothesized that the hydroponic system could be a more efficient methodology for selecting phosphate-solubilizing strains as plant growth promoters. This methodology was tested using the plant as a model. The growth-promoting potential of the strains was compared with that of the Biomaphos® commercial microbial mixture. The obtained calcium phosphate (CaHPO) solubilization results using the hydroponic system were inconsistent with those observed in solid and liquid media. However, the tests in liquid medium demonstrated poor performances of sp. (328EF) and (33EF) in reducing pH and solubilizing CaHPO, which corroborates with the effects of biotic stress observed in plants inoculated with these strains. Nevertheless, the hydroponic system allowed the characterization of (PA12), which is also efficient in solubilization in a liquid medium. The bacterium (PA26) was the most effective in CaHPO solubilization owing to the higher phosphorus (P) absorption, growth promotion, and physiological performance observed in plants inoculated with this bacterium. The hydroponic method proved to be superior in selecting solubilizing strains, allowing the assessment of multiple patterns, such as nutritional level, growth, photosynthetic performance, and anatomical variation in plants, and even the detection of biotic stress responses to inoculation, obtaining strains with higher growth promotion potential than Biomaphos®. This study proposed a new approach to confirm the solubilizing activity of microorganisms previously selected and potentially intended for the bio-input market that are useful in P availability for important crops, such as soybeans.
PubMed: 34777440
DOI: 10.3389/fpls.2021.759463 -
Plants (Basel, Switzerland) Jul 2021Plant growth-promoting rhizobacteria (PGPR) can stimulate disease suppression through the induction of an enhanced state of defense readiness. Here, untargeted...
Plant growth-promoting rhizobacteria (PGPR) can stimulate disease suppression through the induction of an enhanced state of defense readiness. Here, untargeted ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS) and targeted ultra-high performance liquid chromatography coupled to triple-quadrupole mass spectrometry (UHPLC-QqQ-MS) were used to investigate metabolic reprogramming in tomato plant tissues in response to priming by N04 and T22 against . Roots were treated with the two PGPR strains prior to stem inoculation with Metabolites were methanol-extracted from roots, stems and leaves at two-eight days post-inoculation. Targeted analysis by UHPLC-QqQ-MS allowed quantification of aromatic amino acids and phytohormones. For untargeted analysis, UHPLC-MS data were chemometrically processed to determine signatory biomarkers related to priming against . The aromatic amino acid content was differentially reprogrammed in and primed plants responding to . Furthermore, abscisic acid and methyl salicylic acid were found to be major signaling molecules in the tripartite interaction. LC-MS metabolomics analysis showed time-dependent metabolic changes in the primed-unchallenged vs. primed-challenged tissues. The annotated metabolites included phenylpropanoids, benzoic acids, glycoalkaloids, flavonoids, amino acids, organic acids, as well as oxygenated fatty acids. Tissue-specific reprogramming across diverse metabolic networks in roots, stems and leaves was also observed, which demonstrated that PGPR priming resulted in modulation of the defense response to infection.
PubMed: 34451575
DOI: 10.3390/plants10081530 -
Antibiotics (Basel, Switzerland) Aug 2021Honey bees () perform pollination service for many agricultural crops and contribute to the global economy in agriculture and bee products. However, honey bee health is...
Honey bees () perform pollination service for many agricultural crops and contribute to the global economy in agriculture and bee products. However, honey bee health is an ongoing concern, as illustrated by persistent local population decline, caused by some severe bee diseases (e.g., nosemosis, AFB, EFB, chalkbrood) Three natural recipes are in development based on the bioactive compounds of different plants extract ( and ), characterised by HPLC-PDA. The antimicrobial activity of these recipes was tested in vitro against and in vivo against A mix of 20% blueberry, 40% absinthium, 10% oakmoss, 10% oregano, 10% Brewers Gold hops, 5% bay laurel and 5% anise hyssop extract showed the strongest antibacterial and antifungal activity. Combing several highly active plant extracts might be an alternative treatment against bee-disease-associated parasites and pathogens, in particular to replace synthetic antibiotics.
PubMed: 34439010
DOI: 10.3390/antibiotics10080960 -
Plants (Basel, Switzerland) May 2021Grapevine bunch rot, caused by and , causes important economic losses every year in grape production. In the present study, we examined the plant protective activity of...
Grapevine bunch rot, caused by and , causes important economic losses every year in grape production. In the present study, we examined the plant protective activity of the biological control agents, K165, sp. FP12 and sp. FP15 against and on grapes. The in vitro experiments showed that strain K165 significantly reduced the growth of both fungi, while FP15 restricted the growth of and FP12 was ineffective. Following the in vitro experiments, we conducted in planta experiments on grape berries. It was shown that K165, FP12 and FP15 reduced rot severity by 81%, 57% and 37%, respectively, compared to the control, whereas, in the case of , the only protective treatment was that with K165, which reduced rot by 75%. The transcriptomic analysis of the genes encoding the pathogenesis-related proteins PR2, PR3, PR4 and PR5 indicates the activation of multiple defense responses involved in the biocontrol activity of the examined biocontrol agents.
PubMed: 34068090
DOI: 10.3390/plants10050970 -
Open Life Sciences 2020Cellulosic date palm wastes may have beneficial biotechnological applications for eco-friendly utilization. This study reports the isolation of thermophilic...
Cellulosic date palm wastes may have beneficial biotechnological applications for eco-friendly utilization. This study reports the isolation of thermophilic cellulase-producing bacteria and their application in lactic acid production using date palm leaves. The promising isolate was identified as by 16S rRNA gene sequencing. Maximum cellulase production was acquired using alkaline treated date palm leaves (ATDPL) at 48 h and yielded 4.50 U.mL FPase, 8.11 U.mL CMCase, and 2.74 U.mL β-glucosidase. The cellulase activity was optimal at pH 5.0 and 50°C with good stability at a wide temperature (40-70°C) and pH (4.0-7.0) range, demonstrating its suitability in simultaneous saccharification and fermentation. Lactic acid fermentation was optimized at 4 days, pH 5.0, 50°C, 6.0% cellulose of ATDPL, 30 FPU/ g cellulose, 1.0 g. L Tween 80, and 5.0 g. L yeast extract using . The conversion efficiency of lactic acid from the cellulose of ATDPL was 98.71%, and the lactic acid productivity was 0.719 g. L h. Alkaline treatment exhibited a valuable effect on the production of cellulases and lactic acid by reducing the lignin content and cellulose crystallinity. The results of this study offer a credible procedure for using date palm leaves for microbial industrial applications.
PubMed: 33987475
DOI: 10.1515/biol-2020-0019 -
Journal of Experimental Botany May 2021The biocontrol agent Paenibacillus alvei K165 was previously shown to protect Arabidopsis thaliana plants against Verticillium dahliae. Here we show that K165 also...
The biocontrol agent Paenibacillus alvei K165 was previously shown to protect Arabidopsis thaliana plants against Verticillium dahliae. Here we show that K165 also confers inherited immune resistance to V. dahliae. By performing a histone acetyltransferases mutant screen, ChIP assays, and transcriptomic experiments, we were able to show that histone acetylation significantly contributes to the K165 biocontrol activity and establishment of inheritable resistance to V. dahliae. K165 treatment primed the expression of immune-related marker genes and the cinnamyl alcohol dehydrogenase gene CAD3 through the function of histone acetyltransferases. Our results reveal that offspring of plants treated with K165 have primed immunity and enhanced lignification, both contributing towards the K165-mediated inherited immune resistance. Thus, our study paves the way for the use of biocontrol agents for the establishment of inheritable resistance to agronomically important pathogens.
Topics: Ascomycota; Disease Resistance; Gossypium; Paenibacillus; Plant Diseases; Verticillium
PubMed: 33829257
DOI: 10.1093/jxb/erab154 -
Open Life Sciences 2020[This corrects the article DOI: 10.1515/biol-2020-0019.].
[This corrects the article DOI: 10.1515/biol-2020-0019.].
PubMed: 33818580
DOI: 10.1515/biol-2020-0104