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Microbial Biotechnology Jan 2021Rhamnolipids are biosurfactants with a wide range of industrial applications that entered into the market a decade ago. They are naturally produced by Pseudomonas... (Review)
Review
Rhamnolipids are biosurfactants with a wide range of industrial applications that entered into the market a decade ago. They are naturally produced by Pseudomonas aeruginosa and some Burkholderia species. Occasionally, some strains of different bacterial species, like Pseudomonas chlororaphis NRRL B-30761, which have acquired RL-producing ability by horizontal gene transfer, have been described. P. aeruginosa, the ubiquitous opportunistic pathogenic bacterium, is the best rhamnolipids producer, but Pseudomonas putida has been used as heterologous host for the production of this biosurfactant with relatively good yields. The molecular genetics of rhamnolipids production by P. aeruginosa has been widely studied not only due to the interest in developing overproducing strains, but because it is coordinately regulated with the expression of different virulence-related traits by the quorum-sensing response. Here, we highlight how the research of the molecular mechanisms involved in rhamnolipid production have impacted the development of strains that are suitable for industrial production of this biosurfactant, as well as some perspectives to improve these industrial useful strains.
Topics: Glycolipids; Molecular Biology; Pseudomonas; Pseudomonas aeruginosa; Pseudomonas putida; Surface-Active Agents
PubMed: 33151628
DOI: 10.1111/1751-7915.13700 -
Applied and Environmental Microbiology Aug 2017R-type tailocins are high-molecular-weight bacteriocins that resemble bacteriophage tails and are encoded within the genomes of many species. In this study, analysis of...
R-type tailocins are high-molecular-weight bacteriocins that resemble bacteriophage tails and are encoded within the genomes of many species. In this study, analysis of the 30-84 R-tailocin gene cluster revealed that it contains the structural components to produce two R-tailocins of different ancestral origins. Two distinct R-tailocin populations differing in length were observed in UV-induced lysates of 30-84 via transmission electron microscopy. Mutants defective in the production of one or both R-tailocins demonstrated that the killing spectrum of each tailocin is limited to species. The spectra of pseudomonads killed by the two R-tailocins differed, although a few species were either killed by or insusceptible to both tailocins. Tailocin release was disrupted by deletion of the holin gene within the tailocin gene cluster, demonstrating that the lysis cassette is required for the release of both R-tailocins. The loss of functional tailocin production reduced the ability of 30-84 to compete with an R-tailocin-sensitive strain within biofilms and rhizosphere communities. Our study demonstrates that species can produce more than one functional R-tailocin particle sharing the same lysis cassette but differing in their killing spectra. This study provides evidence for the role of R-tailocins as determinants of bacterial competition among plant-associated in biofilms and the rhizosphere. Recent studies have identified R-tailocin gene clusters potentially encoding more than one R-tailocin within the genomes of plant-associated but have not demonstrated that more than one particle is produced or the ecological significance of the production of multiple R-tailocins. This study demonstrates for the first time that strains can produce two distinct R-tailocins with different killing spectra, both of which contribute to bacterial competition between rhizosphere-associated bacteria. These results provide new insight into the previously uncharacterized role of R-tailocin production by plant-associated species in bacterial population dynamics within surface-attached biofilms and on roots.
Topics: Antibiosis; Bacterial Proteins; Bacteriocins; Biofilms; Plant Roots; Pseudomonas; Pseudomonas chlororaphis; Rhizosphere; Soil Microbiology
PubMed: 28526791
DOI: 10.1128/AEM.00706-17 -
Frontiers in Microbiology 2023Phenazine-1-carboxylic acid (PCA) is a biologically active substance with the ability to prevent and control crop diseases. It was certified as a pesticide by the...
Phenazine-1-carboxylic acid (PCA) is a biologically active substance with the ability to prevent and control crop diseases. It was certified as a pesticide by the Ministry of Agriculture of China in 2011 and was named "Shenzimycin." Lzh-T5 is a strain found in the rhizosphere of tomatoes. This strain can produce only 230 mg/L of PCA. We used LDA-4, which produces the phenazine synthetic intermediate trans-2,3-dihydro-3-hydroxyanthranilic acid in high amounts, as the starting strain. By restoring and knocking out , we achieved PCA accumulation. Moreover, PCA production was enhanced after knocking out negative regulators, enhancing the shikimate pathway, and performing fed-batch fermentation, thus resulting in the production of 10,653 mg/L of PCA. It suggested that Lzh-T5 has the potential to become an efficiency cell factory of biologically active substances.
PubMed: 37168109
DOI: 10.3389/fmicb.2023.1186052 -
Frontiers in Plant Science 2022(Pc) representatives are found as part of the rhizosphere-associated microbiome, and different rhizospheric Pc strains frequently perform beneficial activities for the...
(Pc) representatives are found as part of the rhizosphere-associated microbiome, and different rhizospheric Pc strains frequently perform beneficial activities for the plant. In this study we described the interactions between the rhizospheric Pc strains PCL1601, PCL1606 and PCL1607 with a focus on their effects on root performance. Differences among the three rhizospheric Pc strains selected were first observed in phylogenetic studies and confirmed by genome analysis, which showed variation in the presence of genes related to antifungal compounds or siderophore production, among others. Observation of the interactions among these strains under lab conditions revealed that PCL1606 has a better adaptation to environments rich in nutrients, and forms biofilms. Interaction experiments on plant roots confirmed the role of the different phenotypes in their lifestyle. The PCL1606 strain was the best adapted to the habitat of avocado roots, and PCL1607 was the least, and disappeared from the plant root scenario after a few days of interaction. These results confirm that 2 out 3 rhizospheric Pc strains were fully compatible (PCL1601 and PCL1606), efficiently colonizing avocado roots and showing biocontrol activity against the fungal pathogen . The third strain (PCL1607) has colonizing abilities when it is alone on the root but displayed difficulties under the competition scenario, and did not cause deleterious effects on the other Pc competitors when they were present. These results suggest that strains PCL1601 and PCL1606 are very well adapted to the avocado root environment and could constitute a basis for constructing a more complex beneficial microbial synthetic community associated with avocado plant roots.
PubMed: 36589057
DOI: 10.3389/fpls.2022.1063182 -
Microbial Cell Factories May 20202-Acetamidophenol (AAP) is an aromatic compound with the potential for antifungal, anti-inflammatory, antitumor, anti-platelet, and anti-arthritic activities. Due to the...
BACKGROUND
2-Acetamidophenol (AAP) is an aromatic compound with the potential for antifungal, anti-inflammatory, antitumor, anti-platelet, and anti-arthritic activities. Due to the biosynthesis of AAP is not yet fully understood, AAP is mainly produced by chemical synthesis. Currently, metabolic engineering of natural microbial pathway to produce valuable aromatic compound has remarkable advantages and exhibits attractive potential. Thus, it is of paramount importance to develop a dominant strain to produce AAP by elucidating the AAP biosynthesis pathway.
RESULT
In this study, the active aromatic compound AAP was first purified and identified in gene phzB disruption strain HT66ΔphzB, which was derived from Pseudomonas chlororaphis HT66. The titer of AAP in the strain HT66ΔphzB was 236.89 mg/L. Then, the genes involved in AAP biosynthesis were determined. Through the deletion of genes phzF, Nat and trpE, AAP was confirmed to have the same biosynthesis route as phenazine-1-carboxylic (PCA). Moreover, a new arylamine N-acetyltransferases (NATs) was identified and proved to be the key enzyme required for generating AAP by in vitro assay. P. chlororaphis P3, a chemical mutagenesis mutant strain of HT66, has been demonstrated to have a robust ability to produce antimicrobial phenazines. Therefore, genetic engineering, precursor addition, and culture optimization strategies were used to enhance AAP production in P. chlororaphis P3. The inactivation of phzB in P3 increased AAP production by 92.4%. Disrupting the phenazine negative regulatory genes lon and rsmE and blocking the competitive pathway gene pykA in P3 increased AAP production 2.08-fold, which also confirmed that AAP has the same biosynthesis route as PCA. Furthermore, adding 2-amidophenol to the KB medium increased AAP production by 64.6%, which suggested that 2-amidophenol is the precursor of AAP. Finally, by adding 5 mM 2-amidophenol and 2 mM Fe to the KB medium, the production of AAP reached 1209.58 mg/L in the engineered strain P3ΔphzBΔlonΔpykAΔrsmE using a shaking-flask culture. This is the highest microbial-based AAP production achieved to date.
CONCLUSION
In conclusion, this study clarified the biosynthesis process of AAP in Pseudomonas and provided a promising host for industrial-scale biosynthesis of AAP from renewable resources.
Topics: Acetaminophen; Arylamine N-Acetyltransferase; Bacterial Proteins; Biosynthetic Pathways; Genes, Bacterial; Industrial Microbiology; Metabolic Engineering; Pseudomonas chlororaphis
PubMed: 32430011
DOI: 10.1186/s12934-020-01364-7 -
Biology Feb 2022Endophenazine A is a terpenoid phenazine with phenazine-1-carboxylic acid (PCA), and dimethylallyl diphosphate (DMAPP) derived from the 2-methyl-D-erythritol-4-phosphate...
Endophenazine A is a terpenoid phenazine with phenazine-1-carboxylic acid (PCA), and dimethylallyl diphosphate (DMAPP) derived from the 2-methyl-D-erythritol-4-phosphate (MEP) pathway as the precursor, which shows good antimicrobial activity against several Gram-positive bacteria and fungi. However, the highest yield of endophenazine A was about 20 mg/L in , limiting its large-scale industrial development. P3, possessing an efficient PCA synthesis and MEP pathways, is a suitable chassis to synthesize endophenazine A. Herein, we designed an artificial biosynthetic pathway for the synthesis of endophenazine A in P3. Primarily, the prenyltransferase PpzP from 9663 was introduced into P3 and successfully synthesized endophenazine A. Another phenazine compound, endophenazine A1, was discovered and identified as a leakage of the intermediate 4-hydroxy-3-methyl-2-butene pyrophosphate (HMBPP). Finally, the yield of endophenazine A reached 279.43 mg/L, and the yield of endophenazine A1 reached 189.2 mg/L by metabolic engineering and medium optimization. In conclusion, we successfully synthesized endophenazine A and endophenazine A1 in P3 for the first time and achieved the highest titer, which provides a reference for the heterologous synthesis of terpenoid phenazines.
PubMed: 35336738
DOI: 10.3390/biology11030363 -
Journal of Microbiology and... Jan 2019In this study, strain KNU17Pc1 was tested for its antifungal activity against AG-1(IA), which causes banded leaf and sheath blight (BLSB) of maize. KNU17Pc1 was tested...
In this study, strain KNU17Pc1 was tested for its antifungal activity against AG-1(IA), which causes banded leaf and sheath blight (BLSB) of maize. KNU17Pc1 was tested further for its broad-spectrum antifungal activity and in vitro plant growth promoting (PGP) traits. In addition, the in vivo effects of KNU17Pc1 on reduction of BLSB severity and seedling growth promotion of two maize cultivars under greenhouse conditions were investigated. On the basis of multilocus sequence analysis (MLSA), KNU17Pc1 was confirmed as subsp. . The study revealed that KNU17Pc1 had strong in vitro antifungal activity and was effective toward all in vitro PGP traits except phosphate solubilization. In this study, for the first time, a strain of against , , f.sp. , and has been reported. Further biochemical studies showed that KNU17Pc1 was able to produce both types of phenazine derivatives, PCA and 2-OH-PCA. In addition, solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) analysis identified 13 volatile organic compounds (VOCs) in the TSB culture of KNU17Pc1, 1-undecene being the most abundant volatile. Moreover, for the first time, Octamethylcyclotetrasiloxan (D4), dimethyl disulfide, 2-methyl-1,3-butadiene and 1-undecene were detected in . Furthermore, this study reported for the first time the effectiveness of to control BLSB of maize. Hence, further studies are necessary to test the effectiveness of KNU17Pc1 under different environmental conditions so that it can be exploited further for biocontrol and plant growth promotion.
Topics: Antifungal Agents; Mitosporic Fungi; Phenazines; Plant Development; Plant Diseases; Plant Growth Regulators; Pseudomonas chlororaphis; RNA, Ribosomal, 16S; Seedlings; Sequence Analysis, DNA; Volatile Organic Compounds; Zea mays
PubMed: 30415529
DOI: 10.4014/jmb.1808.08026 -
Frontiers in Microbiology 2020PCL1606 (PcPCL1606) is a rhizobacterium isolated from avocado roots, which is a favorable niche for its development. This strain extensively interacts with plant roots...
PCL1606 (PcPCL1606) is a rhizobacterium isolated from avocado roots, which is a favorable niche for its development. This strain extensively interacts with plant roots and surrounding microbes and is considered a biocontrol rhizobacterium. Genome sequencing has shown the presence of thirty-one potential methyl-accepting chemotaxis proteins (MCPs). Among these MCPs, two candidates are putative functional aerotaxis receptors, encoded at locus PCL1606_41090 (1-1) and locus PLC1606_20530 (1-2), that are homologous to the Aer receptor of strain PaO1. Single- and double-deletion mutants in one or both genes have led to motility deficiencies in oxygen-rich areas, particularly reduced swimming motility compared with that of wildtype PcPCL1606. No differences in swarming tests were detected, and less adhesion by the double mutant was observed. However, the single and double mutants on avocado plant roots showed delayed biocontrol ability. During the first days of the biocontrol experiment, the -defective mutants also showed delayed root colonization. The current research characterizes the presence of transductors on . Thus, the functions of the PCL1606_41090 and PCL1606_20530 loci, corresponding to genes 1-1 and 1-2, respectively, are elucidated.
PubMed: 32754135
DOI: 10.3389/fmicb.2020.01560 -
Frontiers in Bioengineering and... 2020P3 has been well-engineered as a platform organism for biologicals production due to enhanced shikimate pathway and excellent physiological and genetic characteristics....
P3 has been well-engineered as a platform organism for biologicals production due to enhanced shikimate pathway and excellent physiological and genetic characteristics. Gentisate displays high antiradical and antioxidant activities and is an important intermediate that can be used as a precursor for drugs. Herein, a plasmid-free biosynthetic pathway of gentisate was constructed by connecting the endogenous degradation pathway from 3-hydroxybenzoate in for the first time. As a result, the production of gentisate reached 365 mg/L from 3-HBA via blocking gentisate conversion and enhancing the gentisate precursors supply through the overexpression of the rate-limiting step. With a close-up at the future perspectives, a series of bioactive compounds could be achieved by constructing synthetic pathways in conventional to establish a cell factory.
PubMed: 33553126
DOI: 10.3389/fbioe.2020.622226 -
Biotechnology For Biofuels 2018Glycerol, an inevitable byproduct of biodiesel, has become an attractive feedstock for the production of value-added chemicals due to its availability and low price....
BACKGROUND
Glycerol, an inevitable byproduct of biodiesel, has become an attractive feedstock for the production of value-added chemicals due to its availability and low price. HT66 can use glycerol to synthesize phenazine-1-carboxamide (PCN), a phenazine derivative, which is strongly antagonistic to fungal phytopathogens. A systematic understanding of underlying mechanisms for the PCN overproduction will be important for the further improvement and industrialization.
RESULTS
We constructed a PCN-overproducing strain (HT66LSP) through knocking out three negative regulatory genes, , , and in HT66. The strain HT66LSP produced 4.10 g/L of PCN with a yield of 0.23 (g/g) from glycerol, which was of the highest titer and the yield obtained among PCN-producing strains. We studied gene expression, metabolomics, and dynamic C tracer in HT66 and HT66LSP. In response to the phenotype changes, the transcript levels of biosynthetic genes, which are responsible for PCN biosynthesis, were all upregulated in HT66LSP. Central carbon was rerouted to the shikimate pathway, which was shown by the modulation of specific genes involved in the lower glycolysis, the TCA cycle, and the shikimate pathway, as well as changes in abundances of intracellular metabolites and flux distribution to increase the precursor availability for PCN biosynthesis. Moreover, dynamic C-labeling experiments revealed that the presence of metabolite channeling of 3-phosphoglyceric acid to phosphoenolpyruvate and shikimate to trans-2,3-dihydro-3-hydroxyanthranilic acid in HT66LSP could enable high-yielding synthesis of PCN.
CONCLUSIONS
The integrated analysis of gene expression, metabolomics, and dynamic C tracer enabled us to gain a more in-depth insight into complex mechanisms for the PCN overproduction. This study provides important basis for further engineering . for high PCN production and efficient glycerol conversion.
PubMed: 29755589
DOI: 10.1186/s13068-018-1123-y