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Plant Disease Jan 2021C-1, a biocontrol agent, was isolated from soil collected from a mountain forest in Korea. Previous studies have shown that certain strains of cause root rot disease...
C-1, a biocontrol agent, was isolated from soil collected from a mountain forest in Korea. Previous studies have shown that certain strains of cause root rot disease in ginseng. To the best of our knowledge, this is the first report of the sequence of the circular chromosome of C-1, which plays a dual role by causing root rot in ginseng and exhibiting biocontrol activity. The findings of this study will assist in analyzing the genes associated with the pathogenicity and biocontrol properties of .
Topics: Panax; Republic of Korea; Serratia
PubMed: 32697179
DOI: 10.1094/PDIS-05-20-1154-A -
Brazilian Journal of Microbiology :... Jul 2019Nine bacterial strains were previously isolated in association with pinewood nematode (PWN) from wilted pine trees. They proved to be nematicidal in vitro, and one of...
Nine bacterial strains were previously isolated in association with pinewood nematode (PWN) from wilted pine trees. They proved to be nematicidal in vitro, and one of the highest activities, with potential to control PWN, was showed by Serratia sp. M24T3. Its ecology in association with plants remains unclear. This study aimed to evaluate the ability of strain M24T3 to colonize the internal tissues of the model plant Arabidopsis thaliana using confocal microscopy. Plant growth-promoting bacteria (PGPB) functional traits were tested and retrieved in the genome of strain M24T3. In greenhouse conditions, the bacterial effects of all nematicidal strains were also evaluated, co-inoculated or not with Bradyrhizobium sp. 3267, on Vigna unguiculata fitness. Inoculation of strain M24T3 increased the number of A. thaliana lateral roots and the confocal analysis confirmed effective bacterial colonization in the plant. Strain M24T3 showed cellulolytic activity, siderophores production, phosphate and zinc solubilization ability, and indole acetic acid production independent of supplementation with L-tryptophan. In the genome of strain M24T3, genes involved in the interaction with the plants such as 1-aminocyclopropane-1-carboxylate (ACC) deaminase, chitinolytic activity, and quorum sensing were also detected. The genomic organization showed ACC deaminase and its leucine-responsive transcriptional regulator, and the activity of ACC deaminase was 594.6 nmol α-ketobutyrate μg protein μl. Strain M24T3 in co-inoculation with Bradyrhizobium sp. 3267 promoted the growth of V. unguiculata. In conclusion, this study demonstrated the ability of strain M24T3 to colonize other plants besides pine trees as an endophyte and displays PGPB traits that probably increased plant tolerance to stresses.
Topics: Animals; Antibiosis; Arabidopsis; Bacterial Proteins; Carbon-Carbon Lyases; Nematoda; Pinus; Plant Diseases; Plant Roots; Quorum Sensing; Serratia; Vigna
PubMed: 31177380
DOI: 10.1007/s42770-019-00098-y -
Journal of Bacteriology Aug 2004The biocontrol activity of various fluorescent pseudomonads towards plant-pathogenic fungi is dependent upon the GacA/GacS-type two-component system of global regulators...
The biocontrol activity of various fluorescent pseudomonads towards plant-pathogenic fungi is dependent upon the GacA/GacS-type two-component system of global regulators and the RpoS transcription sigma factor. In particular, these components are required for the production of antifungal antibiotics and exoenzymes. To investigate the effects of these global regulators on the expression of biocontrol factors by plant-associated bacteria other than Pseudomonas spp., gacA/gacS and rpoS homologues were cloned from biocontrol strain IC1270 of Serratia plymuthica, which produces a set of antifungal compounds, including chitinolytic enzymes and the antibiotic pyrrolnitrin. The nucleotide and deduced protein sequence alignments of the cloned gacA/gacS-like genes-tentatively designated grrA (global response regulation activator) and grrS (global response regulation sensor) and of the cloned rpoS gene revealed 64 to 93% identity with matching genes and proteins of the enteric bacteria Escherichia coli, Pectobacterium carotovora subsp. carotovora, and Serratia marcescens. grrA, grrS, and rpoS gene replacement mutants of strain IC1270 were deficient in the production of pyrrolnitrin, an exoprotease, and N-acylhomoserine lactone quorum-sensing signal molecules. However, neither mutant appeared to differ from the parental strain in the production of siderophores, and only grrA and grrS mutants were deficient in the production of a 58-kDa endochitinase, representing the involvement of other sigma factors in the regulation of strain IC1270's chitinolytic activity. Compared to the parental strain, the grrA, grrS, and rpoS mutants were markedly less capable of suppressing Rhizoctonia solani and Pythium aphanidermatum under greenhouse conditions, indicating the dependence of strain IC1270's biocontrol property on the GrrA/GrrS and RpoS global regulators.
Topics: Antifungal Agents; Bacterial Proteins; Cloning, Molecular; Cucumis sativus; Fabaceae; Gene Expression Regulation, Bacterial; Genes, Regulator; Molecular Sequence Data; Mutation; Pest Control, Biological; Plant Diseases; Pythium; Rhizoctonia; Sequence Analysis, DNA; Serratia; Sigma Factor; Transcription Factors
PubMed: 15262936
DOI: 10.1128/JB.186.15.4986-4993.2004 -
PloS One 2016The sucrose isomerase of Serratia plymuthica AS9 (AS9 PalI) was expressed in Escherichia coli BL21(DE3) and characterized. The half-life of AS9 PalI was 20 min at 45°C,...
The sucrose isomerase of Serratia plymuthica AS9 (AS9 PalI) was expressed in Escherichia coli BL21(DE3) and characterized. The half-life of AS9 PalI was 20 min at 45°C, indicating that it was unstable. In order to improve its thermostability, six amino acid residues with higher B-factors were selected as targets for site-directed mutagenesis, and six mutants (E175N, K576D, K174D, G176D, S575D and N577K) were designed using the RosettaDesign server. The E175N and K576D mutants exhibited improved thermostability in preliminary experiments, so the double mutant E175N/K576D was constructed. These three mutants (E175N, K576D, E175N/K576D) were characterized in detail. The results indicate that the three mutants exhibit a slightly increased optimal temperature (35°C), compared with that of the wild-type enzyme (30°C). The mutants also share an identical pH optimum of 6.0, which is similar to that of the wild-type enzyme. The half-lives of the E175N, K576D and E175N/K576D mutants were 2.30, 1.78 and 7.65 times greater than that of the wild-type enzyme at 45°C, respectively. Kinetic studies showed that the Km values for the E175N, K576D and E175N/K576D mutants decreased by 6.6%, 2.0% and 11.0%, respectively, and their kcat/Km values increased by 38.2%, 4.2% and 19.4%, respectively, compared with those of the wild-type enzyme. After optimizing the conditions for isomaltulose production at 45°C, we found that the E175N, K576D and E175N/K576D mutants displayed slightly improved isomaltulose yields, compared with the wild-type enzyme. Therefore, the mutants produced in this study would be more suitable for industrial biosynthesis of isomaltulose.
Topics: Electrophoresis, Polyacrylamide Gel; Enzyme Stability; Escherichia coli; Glucosyltransferases; Hydrogen-Ion Concentration; Isomaltose; Kinetics; Mutagenesis, Site-Directed; Mutant Proteins; Mutation; Recombinant Proteins; Sequence Analysis, Protein; Serratia; Structural Homology, Protein; Temperature
PubMed: 26886729
DOI: 10.1371/journal.pone.0149208 -
Microorganisms Oct 2022Grapevine trunk diseases (GTDs) are caused by multiple unrelated fungal pathogens, and their management remains difficult worldwide. Biocontrol is an attractive and...
Grapevine trunk diseases (GTDs) are caused by multiple unrelated fungal pathogens, and their management remains difficult worldwide. Biocontrol is an attractive and sustainable strategy given the current need for a cleaner viticulture. In this study, twenty commercial vineyards were sampled across California to isolate endophytic and rhizospheric bacteria from different grapevine cultivars with the presence and absence of GTD symptoms. A collection of 1344 bacterial isolates were challenged in vitro against and , from which a subset of 172 isolates exerted inhibition levels of mycelial growth over 40%. Bacterial isolates were identified as ( 154), spp. ( 12), ( 2) and others that were later excluded ( 4). Representative isolates of , and were challenged against six other fungal pathogens responsible for GTDs. Mycelial inhibition levels were consistent across bacterial species, being slightly higher against slow-growing fungi than against Botryosphaeriaceae. Moreover, agar-diffusible metabolites of strongly inhibited the growth of and , at 1, 15, and 30% /. The agar-diffusible metabolites of and , however, caused lower inhibition levels against both pathogens, but their volatile organic compounds showed antifungal activity against both pathogens. These results suggest that , and constitute potential biocontrol agents (BCAs) against GTDs and their application in field conditions should be further evaluated.
PubMed: 36296311
DOI: 10.3390/microorganisms10102035 -
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 -
Research in Microbiology Apr 2016The σ(S) subunit RpoS of RNA polymerase functions as a master regulator of the general stress response in Escherichia coli and related bacteria. RpoS has been reported...
The σ(S) subunit RpoS of RNA polymerase functions as a master regulator of the general stress response in Escherichia coli and related bacteria. RpoS has been reported to modulate biocontrol properties in the rhizobacterium Serratia plymuthica IC1270. However, the role of RpoS in the stress response and biofilm formation in S. plymuthica remains largely unknown. Here we studied the role of RpoS from an endophytic S. plymuthica G3 in regulating these phenotypes. Mutational analysis demonstrated that RpoS positively regulates the global stress response to acid or alkaline stresses, oxidative stress, hyperosmolarity, heat shock and carbon starvation, in addition to proteolytic and chitinolytic activities. Interestingly, rpoS mutations resulted in significantly enhanced swimming motility, biofilm formation and production of the plant auxin indole-3-acetic acid (IAA), which may contribute to competitive colonization and environmental fitness for survival. These findings provide further insight into the strain-specific role of RpoS in the endophytic strain G3 of S. plymuthica, where it confers resistance to general stresses encountered within the plant environment. The heterogeneous functionality of RpoS in rhizosphere and endophytic S. plymuthica populations may provide a selective advantage for better adaptation to various physiological and environmental stresses.
Topics: Bacterial Proteins; Biofilms; DNA Mutational Analysis; Endophytes; Locomotion; Plant Growth Regulators; Serratia; Sigma Factor; Stress, Physiological
PubMed: 26671319
DOI: 10.1016/j.resmic.2015.11.003 -
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 -
BMC Plant Biology Jan 2009Induced resistance is a state of enhanced defensive capacity developed by a plant reacting to specific biotic or chemical stimuli. Over the years, several forms of...
BACKGROUND
Induced resistance is a state of enhanced defensive capacity developed by a plant reacting to specific biotic or chemical stimuli. Over the years, several forms of induced resistance have been characterized, including systemic acquired resistance, which is induced upon localized infection by an avirulent necrotizing pathogen, and induced systemic resistance (ISR), which is elicited by selected strains of nonpathogenic rhizobacteria. However, contrary to the relative wealth of information on inducible defense responses in dicotyledoneous plants, our understanding of the molecular mechanisms underlying induced resistance phenomena in cereal crops is still in its infancy. Using a combined cytomolecular and pharmacological approach, we analyzed the host defense mechanisms associated with the establishment of ISR in rice by the rhizobacterium Serratia plymuthica IC1270.
RESULTS
In a standardized soil-based assay, root treatment with IC1270 rendered foliar tissues more resistant to the hemibiotrophic pathogen Magnaporthe oryzae, causal agent of the devastating rice blast disease. Analysis of the cytological and biochemical alterations associated with restriction of fungal growth in IC1270-induced plants revealed that IC1270 primes rice for enhanced attacker-induced accumulation of reactive oxygen species (ROS) and autofluorescent phenolic compounds in and near epidermal cells displaying dense cytoplasmic granulation. Similar, yet more abundant, phenotypes of hypersensitively dying cells in the vicinity of fungal hyphae were evident in a gene-for-gene interaction with an avirulent M. oryzae strain, suggesting that IC1270-inducible ISR and R protein conditioned effector-triggered immunity (ETI) target similar defense mechanisms. Yet, this IC1270-inducible ISR response seems to act as a double-edged sword within the rice defense network as induced plants displayed an increased vulnerability to the necrotrophic pathogens Rhizoctonia solani and Cochliobolus miyabeanus. Artificial enhancement of ROS levels in inoculated leaves faithfully mimicked the opposite effects of IC1270 bacteria on aforementioned pathogens, suggesting a central role for oxidative events in the IC1270-induced resistance mechanism.
CONCLUSION
Besides identifying ROS as modulators of antagonistic defense mechanisms in rice, this work reveals the mechanistic similarities between S. plymuthica-mediated ISR and R protein-dictated ETI and underscores the importance of using appropriate innate defense mechanisms when breeding for broad-spectrum rice disease resistance.
Topics: Immunity, Innate; Magnaporthe; Oryza; Oxidation-Reduction; Oxidative Stress; Plant Diseases; Plant Leaves; Plant Roots; Reactive Oxygen Species; Rhizoctonia; Serratia
PubMed: 19161601
DOI: 10.1186/1471-2229-9-9 -
BMC Genomics Aug 2015Improved understanding of bacterial-fungal interactions in the rhizosphere should assist in the successful application of bacteria as biological control agents against...
BACKGROUND
Improved understanding of bacterial-fungal interactions in the rhizosphere should assist in the successful application of bacteria as biological control agents against fungal pathogens of plants, providing alternatives to chemicals in sustainable agriculture. Rhizoctonia solani is an important soil-associated fungal pathogen and its chemical treatment is not feasible or economic. The genomes of the plant-associated bacteria Serratia proteamaculans S4 and Serratia plymuthica AS13 have been sequenced, revealing genetic traits that may explain their diverse plant growth promoting activities and antagonistic interactions with R. solani. To understand the functional response of this pathogen to different bacteria and to elucidate whether the molecular mechanisms that the fungus exploits involve general stress or more specific responses, we performed a global transcriptome profiling of R. solani Rhs1AP anastomosis group 3 (AG-3) during interaction with the S4 and AS13 species of Serratia using RNA-seq.
RESULTS
Approximately 104,504 million clean 75-100 bp paired-end reads were obtained from three libraries, each in triplicate (AG3-Control, AG3-S4 and AG3-AS13). Transcriptome analysis revealed that approximately 10% of the fungal transcriptome was differentially expressed during challenge with Serratia. The numbers of S4- and AS13-specific differentially expressed genes (DEG) were 866 and 292 respectively, while there were 1035 common DEGs in the two treatment groups. Four hundred and sixty and 242 genes respectively had values of log2 fold-change > 3 and for further analyses this cut-off value was used. Functional classification of DEGs based on Gene Ontology enrichment analysis and on KEGG pathway annotations revealed a general shift in fungal gene expression in which genes related to xenobiotic degradation, toxin and antioxidant production, energy, carbohydrate and lipid metabolism and hyphal rearrangements were subjected to transcriptional regulation.
CONCLUSIONS
This RNA-seq profiling generated a novel dataset describing the functional response of the phytopathogen R. solani AG3 to the plant-associated Serratia bacteria S4 and AS13. Most genes were regulated in the same way in the presence of both bacterial isolates, but there were also some strain-specific responses. The findings in this study will be beneficial for further research on biological control and in depth exploration of bacterial-fungal interactions in the rhizosphere.
Topics: Antibiosis; Fungal Proteins; Gene Expression Profiling; Gene Expression Regulation, Fungal; Gene Ontology; RNA, Fungal; RNA, Messenger; Rhizoctonia; Rhizosphere; Sequence Analysis, RNA; Serratia; Species Specificity
PubMed: 26296338
DOI: 10.1186/s12864-015-1758-z