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Microbial Cell Factories May 2024Aminopyrrolnitrin (APRN), a natural halogenated phenylpyrrole derivative (HPD), has strong antifungal and antiparasitic activities. Additionally, it showed 2.8-fold...
Aminopyrrolnitrin (APRN), a natural halogenated phenylpyrrole derivative (HPD), has strong antifungal and antiparasitic activities. Additionally, it showed 2.8-fold increased photostability compared to pyrrolnitrin, a commercially available HPD with antimicrobial activity. For microbial production of APRN, we first engineered anthranilate phosphoribosyltransferase encoded by trpD from Corynebacterium glutamicum, resulting in a TrpD mutation that exhibits feedback-resistant against L-tryptophan and higher substrate affinity compared to wild-type TrpD. Plasmid-borne expression of trpD in C. glutamicum TP851 strain with two copies of trpD in the genome led to the production of 3.1 g/L L-tryptophan in flask culture. Subsequent step for L-tryptophan chlorination into 7-chloro-L-tryptophan was achieved by introducing diverse sources of genes encoding tryptophan 7-halogenase (PrnA or RebH) and flavin reductase (Fre, PrnF, or RebF). The combined expression of prnA from Serratia grimesii or Serratia plymuthica with flavin reductase gene from Escherichia coli, Pseudomonas fluorescens, or Lechevalieria aerocolonigenes yielded higher production of 7-chloro-L-tryptophan in comparison to other sets of two-component systems. In the next step, production of putative monodechloroaminopyrrolnitrin (MDAP) from 7-chloro-L-tryptophan was achieved through the expression of prnB encoding MDAP synthase from S. plymuthica or P. fluorescens. Finally, an artificial APRN biosynthetic pathway was constructed by simultaneously expressing genes coding for tryptophan 7-halogenase, flavin reductase, MDAP synthase, and MDAP halogenase (PrnC) from different microbial sources within the L-tryptophan-producing TP851 strain. As prnC from S. grimesii or S. plymuthica was introduced into the host strain, which carried plasmids expressing prnA from S. plymuthica, fre from E. coli, and prnB from S. plymuthica, APN3639 and APN3638 accumulated 29.5 mg/L and 28.1 mg/L of APRN in the culture broth. This study represents the first report on the fermentative APRN production by metabolically engineered C. glutamicum.
Topics: Corynebacterium glutamicum; Metabolic Engineering; Pyrrolnitrin; Fermentation; Bacterial Proteins; Tryptophan; Escherichia coli; Oxidoreductases
PubMed: 38783320
DOI: 10.1186/s12934-024-02424-y -
BMC Microbiology Apr 2024Kojic acid is a wonderful fungal secondary metabolite that has several applications in the food, medical, and agriculture sectors. Many human diseases become resistant...
Production of kojic acid by Aspergillus flavus OL314748 using box-Behnken statistical design and its antibacterial and anticancer applications using molecular docking technique.
Kojic acid is a wonderful fungal secondary metabolite that has several applications in the food, medical, and agriculture sectors. Many human diseases become resistant to normal antibiotics and normal treatments. We need to search for alternative treatment sources and understand their mode of action. Aspergillus flavus ASU45 (OL314748) was isolated from the caraway rhizosphere as a non-aflatoxin producer and identified genetically using 18S rRNA gene sequencing. After applying the Box-Behnken statistical design to maximize KA production, the production raised from 39.96 to 81.59 g/l utilizing (g/l) glucose 150, yeast extract 5, KHPO 1, MgSO.7HO 2, and medium pH 3 with a coefficient (R) of 98.45%. Extracted KA was characterized using FTIR, XRD, and a scanning electron microscope. Crystalized KA was an effective antibacterial agent against six human pathogenic bacteria (Bacillus cereus, Staphylococcus aureus, Escherichia coli, Klebsiella pneumonia, Serratia marcescens, and Serratia plymuthica). KA achieves high inhibition activity against Bacillus cereus, K. pneumonia, and S. plymuthica at 100 μg/ml concentration by 2.75, 2.85, and 2.85 compared with chloramphenicol which gives inhibition zones 1, 1.1, and 1.6, respectively. Crystalized KA had anticancer activity versus three types of cancer cell lines (Mcf-7, HepG2, and Huh7) and demonstrated high cytotoxic capabilities on HepG-2 cells that propose strong antitumor potent of KA versus hepatocellular carcinoma. The antibacterial and anticancer modes of action were illustrated using the molecular docking technique. Crystalized kojic acid from a biological source represented a promising microbial metabolite that could be utilized as an alternative antibacterial and anticancer agent effectively.
Topics: Aspergillus flavus; Pyrones; Anti-Bacterial Agents; Humans; Molecular Docking Simulation; Antineoplastic Agents; Microbial Sensitivity Tests; Cell Line, Tumor; Bacteria
PubMed: 38658810
DOI: 10.1186/s12866-024-03289-2 -
Gels (Basel, Switzerland) Oct 2023The textile industry stands as a prominent contributor to global environmental pollution, primarily attributable to its extensive reliance on synthetic dyes, hazardous...
The textile industry stands as a prominent contributor to global environmental pollution, primarily attributable to its extensive reliance on synthetic dyes, hazardous components, and solvents throughout the textile dyeing and treatment processes. Consequently, the pursuit of sustainable textile solutions becomes imperative, aimed at replacing these environmentally unfriendly constituents with biobased and bioactive pigments, antibacterial agents, and, notably, natural solvents. Achieving this goal is a formidable yet indispensable challenge. In this study, the dyeing ability of the crude gel prodigiosin, produced by non-pathogenic bacteria , was investigated on various multifiber fabrics at different conditions (temperature and pH) and by using salts and alternative mordants (the conventional Ferrous Sulphate (FeSO) and a new bio-mordant, L-Cysteine (L-Cys)). Additionally, a novel gel-based Choline chloride (ChCl)/Lactic acid (LA) (1:2) deep eutectic solvent (DES) dyeing medium was studied to replace the organic solvents. Nylon fabrics dyed with 3.0% over the weight of the fiber () L-Cys at pH = 8.3 had improved color fastness to washing, while the gel-based ChCl/LA (1:2) DES dyebath provided a better color fastness to light. Moreover, nylon fabrics under these conditions exhibited remarkable antimicrobial activity against () and (). In conclusion, the utilization of the crude gel-based prodigiosin pigment demonstrates a distinct advantage in dyeing textile materials, aligning with the growing consumer demand for more eco-friendly and sustainable products. Additionally, the application of the natural reducing agent L-Cys, previously untested as a bio-mordant, in conjunction with the use of gel-based DES as a dyeing medium, has showcased improved colorimetric and antibacterial properties when applied to nylon that is dyed with the crude gel prodigiosin pigment.
PubMed: 37888373
DOI: 10.3390/gels9100800 -
Frontiers in Plant Science 2023The use of biocontrol agents with plant growth-promoting activity has emerged as an approach to support sustainable agriculture. During our field evaluation of potato...
The use of biocontrol agents with plant growth-promoting activity has emerged as an approach to support sustainable agriculture. During our field evaluation of potato plants treated with biocontrol rhizobacteria, four bacteria were associated with increased plant height. Using two important solanaceous crop plants, tomato and potato, we carried out a comparative analysis of the growth-promoting activity of the four bacterial strains: SLU99, S412, AV10, and EV23. Greenhouse and experiments showed that SLU99 promoted plant height, biomass accumulation, and yield of potato and tomato plants, while EV23 promoted growth in potato but not in tomato plants. SLU99 induced the expression of plant hormone-related genes in potato and tomato, especially those involved in maintaining homeostasis of auxin, cytokinin, gibberellic acid and ethylene. Our results reveal potential mechanisms underlying the growth promotion and biocontrol effects of these rhizobacteria and suggest which strains may be best deployed for sustainably improving crop yield.
PubMed: 37534284
DOI: 10.3389/fpls.2023.1141692 -
Microbial Biotechnology Aug 2023Indole-3-acetic acid (IAA) is emerging as a key intra- and inter-kingdom signal molecule that modulates a wide range of processes of importance during...
Indole-3-acetic acid (IAA) is emerging as a key intra- and inter-kingdom signal molecule that modulates a wide range of processes of importance during plant-microorganism interaction. However, the mechanisms by which IAA carries out its functions in bacteria as well as the regulatory processes by which bacteria modulate auxin production are largely unknown. Here, we found that IAA synthesis deficiency results in important global transcriptional changes in the broad-range antibiotic-producing rhizobacterium Serratia plymuthica A153. Most pronounced transcriptional changes were observed in various gene clusters for aromatic acid metabolism, including auxin catabolism. To delve into the corresponding molecular mechanisms, different regulatory proteins were biochemically characterized. Among them, a TyrR orthologue was essential for IAA production through the activation of the ipdc gene encoding a key enzyme for IAA biosynthesis. We showed that TyrR specifically recognizes different aromatic amino acids which, in turn, alters the interactions of TyrR with the ipdc promoter. Screening of mutants defective in various transcriptional and post-transcriptional regulators allowed the identification of additional regulators of IAA production, including PigP and quorum sensing-related genes. Advancing our knowledge on the mechanisms that control the IAA biosynthesis in beneficial phytobacteria is of biotechnological interest for improving agricultural productivity and sustainable agricultural development.
Topics: Indoleacetic Acids; Serratia; Transcription Factors; Plant Growth Regulators
PubMed: 37345981
DOI: 10.1111/1751-7915.14296 -
Frontiers in Plant Science 2023Non-rhizobial endophytes (NREs) are active colonizers inhabiting the root nodules. Though their active role in the lentil agroecosystem is not well defined, here we...
Non-rhizobial endophytes (NREs) are active colonizers inhabiting the root nodules. Though their active role in the lentil agroecosystem is not well defined, here we observed that these NREs might promote the growth of lentils, modulate rhizospheric community structure and could be used as promising organisms for optimal use of rice fallow soil. NREs from root nodules of lentils were isolated and examined for plant growth-promoting traits, exopolysaccharide (EPS) and biofilm production, root metabolites, and the presence of nifH and nifK elements. The greenhouse experiment with the chosen NREs, i.e., Serratia plymuthica 33GS and Serratia sp. R6 significantly increased the germination rate, vigour index, development of nodules (in non-sterile soil) and fresh weight of nodules (33GS 94%, R6 61% growth) and length of the shoot (33GS 86%, R6 51.16%) as well as chlorophyll levels when compared to the uninoculated control. Scanning Electron Microscopy (SEM) revealed that both isolates could successfully colonize the roots and elicit root hair growth. The inoculation of the NREs resulted in specific changes in root exudation patterns. The plants with 33GS and R6 treatment significantly stimulated the exudation of triterpenes, fatty acids, and their methyl esters in comparison to the uninoculated plants, altering the rhizospheric microbial community structure. Proteobacteria dominated the rhizospheric microbiota in all the treatments. Treatment with 33GS or R6 also enhanced the relative abundance of other favourable microbes, including Rhizobium, Mesorhizobium, and Bradyrhizobium. The correlation network analysis of relative abundances resulted in numerous bacterial taxa, which were in cooperation with each other, having a possible role in plant growth promotion. The results indicate the significant role of NREs as plant growth promoters, which also includes their role in root exudation patterns, enhancement of soil nutrient status and modulation of rhizospheric microbiota, suggesting their prospects in sustainable, and bio-based agriculture.
PubMed: 37113600
DOI: 10.3389/fpls.2023.1152875 -
Frontiers in Microbiology 2023Several seed priming methods can be used to improve seed germination, seedling vigor, and to overcome abiotic stress. In addition to these benefits, only the biopriming...
Several seed priming methods can be used to improve seed germination, seedling vigor, and to overcome abiotic stress. In addition to these benefits, only the biopriming method provides the additional benefit of biotic stress management, earning it special attention. Seed biopriming is useful in almost all crops around the world and is an environmentally friendly alternative to chemical fungicides. Biopriming usually refers to use of beneficial microorganisms, in particular plant growth-promoting bacteria (PGPB) able to survive under various harsh environmental conditions. In this study, various bacterial strains were isolated from samples of different origins, i.e., rhizospheric soil, desert sand, and sea mud. Preliminary screening of 156 bacterial isolates was conducted on the basis of their potassium (K), phosphorus (P) solubilization ability, and production of plant growth hormone, i.e., indole acetic acid (IAA). The most efficient bacteria were identified by 16S rRNA gene nucleotide sequences and further examined for their ACC deaminase activity, ammonia production, and biocontrol activity (defined chitinolytic activity, HCN, and siderophores production). Finally, carrot seed germination assay was conducted with 10 shortlisted most potent isolates. 68.6, 58.3, and 66.7% of tested bacterial isolates were capable of P, K, and Zn solubilization, respectively. AF3II1 showed the highest P and K solubilization, while isolate AF4II5, AF7II3, and PC3 showed the highest IAA synthesis ability. EDC15 and AF1I1 showed the strongest chitinolytic and siderophore production activity, respectively. Seven isolates demonstrated strong HCN production ability. Five isolates improved carrot seed germination. Only selected isolates with plant growth-promoting properties can improve carrot germination. The results of this study demonstrate that mainly auxins are involved in seed germination. Furthermore, the data suggest that phosphate solubilization ability may play an additional role in seed germination.
PubMed: 36925481
DOI: 10.3389/fmicb.2023.1142966 -
Plant Physiology Mar 2023N-acyl homoserine lactones (AHLs) are important players in plant-bacteria interactions. Different AHL-producing bacteria can improve plant growth and resistance against...
N-acyl homoserine lactones (AHLs) are important players in plant-bacteria interactions. Different AHL-producing bacteria can improve plant growth and resistance against plant pathogens. In nature, plants may host a variety of AHL-producing bacteria and frequently experience numerous AHLs at the same time. Therefore, a coordinated response to combined AHL molecules is necessary. The purpose of this study was to explore the mechanism of AHL-priming using combined AHL molecules including N-(3-oxo-hexanoyl)-L-homoserine lactone, N-3-oxo-octanoyl-L-homoserine lactone, N-3-oxo-dodecanoyl-L-homoserine lactone, and N-3-oxo-tetradecanoyl-L-homoserine lactone and AHL-producing bacteria including Serratia plymuthica HRO-C48, Rhizobium etli CFN42, Burkholderia graminis DSM17151, and Ensifer meliloti (Sinorhizobium meliloti) Rm2011. We used transcriptome analysis, phytohormone measurements, as well as genetic and microbiological approaches to assess how the combination of structurally diverse AHL molecules influence Arabidopsis (Arabidopsis thaliana). Our findings revealed a particular response to a mixture of AHL molecules (AHL mix). Different expression patterns indicated that the reaction of plants exposed to AHL mix differs from that of plants exposed to single AHL molecules. In addition, different content of jasmonic acid (JA) and derivatives revealed that jasmonates play an important role in AHL mix-induced priming. The fast and stable decreased concentration of COOH-JA-Ile after challenge with the flagellin-derived peptide flg22 indicated that AHL mix modifies the metabolism of jasmonates. Study of various JA- and salicylic acid-related Arabidopsis mutants strengthened the notion that JA homeostasis is involved in AHL-priming. Understanding how the combination of AHLs primes plants for enhanced resistance has the potential to broaden our approaches in sustainable agriculture and will help to effectively protect plants against pathogens.
Topics: Arabidopsis; Acyl-Butyrolactones; Quorum Sensing; Bacteria; Plants
PubMed: 36649188
DOI: 10.1093/plphys/kiad017 -
MBio Feb 2023Bacteria have evolved a sophisticated array of signal transduction systems that allow them to adapt their physiology and metabolism to changing environmental conditions....
Bacteria have evolved a sophisticated array of signal transduction systems that allow them to adapt their physiology and metabolism to changing environmental conditions. Typically, these systems recognize signals through dedicated ligand binding domains (LBDs) to ultimately trigger a diversity of physiological responses. Nonetheless, an increasing number of reports reveal that signal transduction receptors also bind antagonists to inhibit responses mediated by agonists. The mechanisms by which antagonists block the downstream signaling cascade remain largely unknown. To advance our knowledge in this field, we used the LysR-type transcriptional regulator AdmX as a model. AdmX activates the expression of an antibiotic biosynthetic cluster in the rhizobacterium Serratia plymuthica. AdmX specifically recognizes the auxin phytohormone indole-3-acetic acid (IAA) and its biosynthetic intermediate indole-3-pyruvic acid (IPA) as signals. However, only IAA, but not IPA, was shown to regulate antibiotic production in . Here, we report the high-resolution structures of the LBD of AdmX in complex with IAA and IPA. We found that IAA and IPA compete for binding to AdmX. Although IAA and IPA binding does not alter the oligomeric state of AdmX, IPA binding causes a higher degree of compactness in the protein structure. Molecular dynamics simulations revealed significant differences in the binding modes of IAA and IPA by AdmX, and the inspection of the three-dimensional structures evidenced differential agonist- and antagonist-mediated structural changes. Key residues for auxin binding were identified and an auxin recognition motif defined. Phylogenetic clustering supports the recent evolutionary emergence of this motif specifically in plant-associated enterobacteria. Although antagonists were found to bind different bacterial signal transduction receptors, we are still at the early stages of understanding the molecular details by which these molecules exert their inhibitory effects. Here, we provide insight into the structural changes resulting from the binding of an agonist and an antagonist to a sensor protein. Our data indicate that agonist and antagonist recognition is characterized by small conformational differences in the LBDs that can be efficiently transmitted to the output domain to modulate the final response. LBDs are subject to strong selective pressures and are rapidly evolving domains. An increasing number of reports support the idea that environmental factors drive the evolution of sensor domains. Given the recent evolutionary history of AdmX homologs, as well as their narrow phyletic distribution within plant-associated bacteria, our results are in accordance with a plant-mediated evolutionary process that resulted in the emergence of receptor proteins that specifically sense auxin phytohormones.
Topics: Phylogeny; Indoleacetic Acids; Plant Growth Regulators; Plants; Bacteria; Anti-Bacterial Agents
PubMed: 36602305
DOI: 10.1128/mbio.03363-22 -
Pathogens (Basel, Switzerland) Dec 2022Efforts to combat antimicrobial resistance (AMR) should be based on the One Health approach, involving human health, animal health, and the environment. In Ghana,...
BACKGROUND
Efforts to combat antimicrobial resistance (AMR) should be based on the One Health approach, involving human health, animal health, and the environment. In Ghana, previous studies on AMR have given little attention to animal source food, a major route of transmission of antibiotic-resistant zoonotic pathogens. The aim of this study was to investigate the occurrence of multidrug-resistant (MDR) bacteria in meat sold in Accra.
METHODS
This was a cross-sectional study in which 270 meat samples (90 each of beef, goat meat, and chicken) were collected, and investigated for contamination with multidrug-resistant bacteria. The bacteria were subjected to susceptibility testing against amikacin (30 µg), ampicillin (10 µg), amoxicillin-clavulanate (20/10 µg), cefuroxime (30 µg), ceftriaxone (30 µg), ceftazidime (30 µg), cefepime (30 µg), ciprofloxacin (5 µg), trimethoprim-sulfamethoxazole (1.25/23.75 µg), ertapenem (10 µg), meropenem (10 µg), imipenem (10 µg), tigecycline (15 µg), and gentamicin (10 µg).
RESULTS
Thirty-two different types of bacteria, totalling 558, were isolated, the predominant being (44.6%), (19.9%), (3.4%), (3.2%), and (3.1%). The prevalence of MDR among the contaminating bacteria was 14.9%. The MDR distribution among the predominant bacteria was (18.7%), (11.1%), and (0.0% each), and (5.6%). Moreover, 2.0% of the contaminating bacteria were extended-spectrum beta-lactamase (ESBL) producers, all of which occurred in the chicken samples, and their distribution was: (1.3%), , spp., , and (0.2% each).
CONCLUSIONS
The meat samples were heavily contaminated with and , and less frequently, with , , and other organisms. The prevalence of multidrug-resistant bacteria was moderate (14.9%), while that of ESBL producers was low (2%).
PubMed: 36558851
DOI: 10.3390/pathogens11121517