Antibiotic activity of soil myxobacteria and its ecological implications

Foster, H. A.; Yasouri, F. N.; Daoud, Nabeel N.

doi:10.1111/j.1574-6941.1992.tb01645.x

Cited by 3 publications

(1 citation statement)

References 16 publications

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“…The majority of active strains belonged to the Myxococcus genus, which was indeed the most frequently isolated. Foster et al [25] reported that out of 64 strains, 77% inhibited growth of Micrococcus luteus and 23% shown antifungal activities. Norén and Raper [26] found that the tested myxobacteria were able to produce antibacterial agents that, however, were active only in Gram-positive eubacteria, the Gram-negative species being unaffected by the agents.…”

Section: Biological Screening Against Test Microorganismsmentioning

confidence: 99%

Isolation, antimicrobial activity of myxobacterial crude extracts and identification of the most potent strains

Charousová

Medo

Javoreková

2017

Arch biol sci (Beogr)

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Broad spectrum antimicrobial agents are urgently needed to fight frequently occurring multidrug-resistant pathogens. Myxobacteria have been regarded as "microbe factories" for active secondary metabolites, and therefore, this study was performed to isolate two bacteriolytic genera of myxobacteria, Myxococcus sp. and Corallococcus sp., from 10 soil/sand samples using two conventional methods followed by purification with the aim of determining the antimicrobial activity of methanol extracts against 11 test microorganisms (four Gram-positive, four Gram-negative, two yeasts and one fungus). Out of thirty-nine directly observed strains, 23 were purified and analyzed for antimicrobial activities. Based on the broth microdilution method, a total of 19 crude extracts showed antimicrobial activity. The range of inhibited wells was more important in the case of anti-Gram-positive-bacterial activity in comparison with the anti-Gram-negative-bacterial and antifungal activity. In light of the established degree and range of antimicrobial activity, two of the most active isolates (BNEM1 and SFEC2) were selected for further characterization. Morphological parameters and a sequence similarity search by BLAST revealed that they showed 99% sequence similarity to Myxococcus xanthus − BNEM1 (accession no. KX669224) and Corallococcus coralloides -SFEC2 (accession no. KX669225). As these isolates had antimicrobial activity, they could be considered for use in the development of antibiotics for pharmaceutical use.

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Section: Biological Screening Against Test Microorganismsmentioning

confidence: 99%

Isolation, antimicrobial activity of myxobacterial crude extracts and identification of the most potent strains

Charousová

Medo

Javoreková

2017

Arch biol sci (Beogr)

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Cryptic carbapenem antibiotic production genes are widespread in Erwinia carotovora: facile trans activation by the carR transcriptional regulator

et al. 1998

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Few strains of Erwinia carotovora subsp. carotovora (Ecc) make carbapenem antibiotics. Strain GS101 makes the basic carbapenem molecule, 1-carbapen-2-em-3-carboxylic acid (Car). The production of this antibiotic has been shown to be cell density dependent, requiring the accumulation of the small diffusible molecule N-(3-oxohexanoyl)-L-homoserine lactone (OHHL) in the growth medium. When the concentration of this inducer rises above a threshold level, OHHL is proposed to interact with the transcriptional activator of the carbapenem cluster (CarR) and induce carbapenem biosynthesis. The introduction of the GS101 carR gene into an Ecc strain (SCRI 193) which is naturally carbapenem-negative resulted in the production of Car. This suggested that strain SCRI 193 contained functional cryptic carbapenem biosynthetic genes, but lacked a functional carR homologue. The distribution of trans-activatable antibiotic genes was assayed in Erwinia strains from a culture collection and was found to be common in a large proportion of fee strains. Significantly, amongst the Ecc strains identified, a larger proportion contained trans-activatable cryptic genes than produced antibiotics constitutively. Southern hybridization of the chromosomal DNA of cryptic Ecc strains confirmed the presence of both the car biosynthetic cluster and the regulatory genes. Identification of homologues of the transcriptional activator carR suggests that the cause of the silencing of the carbapenem biosynthetic cluster in these strains is not the deletion of carR. In an attempt to identify the cause of the silencing in the Ecc strain SCRI 193 the carR homologue from this strain was cloned and sequenced. The SCRI 193 CarR homologue was 94% identical to the GS101 CarR and contained 14 amino acid substitutions. Both homologues could be expressed from their native promoters and ribosome-binding sites using an in vitro prokaryotic transcription and translation assay, and when the SCRI 193 carR homologue was cloned in multicopy plasmids and reintroduced into SCRI 193, antibiotic production was observed. This suggested that the mutation causing the silencing of the biosynthetic cluster in SCRI 193 was leaky and the cryptic Car phenotype could be suppressed by multiple copies of the apparently mutant transcriptional activator.

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Bacterial predation of a fungal wheat pathogen: Prelude to experimental evolution of enhanced biocontrol agents

et al. 2023

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Research to identify appropriate biological agents for controlling pathogens might exploit experimental evolution to select for enhanced antagonism against pathogens. We developed an experimental regime facilitating this approach, featuring the bacterial broad‐spectrum predator Myxococcus xanthus and the fungal wheat pathogen Zymoseptoria tritici. We demonstrate that Z. tritici, a major cause of crop loss and fungicide use worldwide, both fuels growth of and is killed by M. xanthus on wheat straw, a probable source of seedling infection. M. xanthus was found capable of growth on moistened straw alone, unaided by Z. tritici, in a manner dependent on both M. xanthus initial density and on how long straw was moistened before M. xanthus inoculation. Such growth of non‐cellulolytic myxobacteria on plant detritus may have implications for understanding their roles in nutrient cycling. However, straw with Z. tritici was found to fuel greater M. xanthus growth than straw alone under many conditions. After shorter moistening periods, growth by low‐density M. xanthus populations was found to be fully dependent on Z. tritici. Such pathogen‐dependent M. xanthus populations could be sustained with population replacement over five 1‐week growth cycles, indicating the feasibility of conducting long‐term experimental evolution with this system. Furthermore, M. xanthus was found to kill majorities of Z. tritici populations on both buffered agar and straw. Our results suggest that myxobacteria may serve as effective biocontrol agents of Z. tritici and are amenable to long‐term experimental selection for enhanced killing of this pathogen, an approach broadly applicable to many potential biocontrol agents and target pathogens.

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Antibiotic activity of soil myxobacteria and its ecological implications

Cited by 3 publications

References 16 publications

Isolation, antimicrobial activity of myxobacterial crude extracts and identification of the most potent strains

Isolation, antimicrobial activity of myxobacterial crude extracts and identification of the most potent strains

Cryptic carbapenem antibiotic production genes are widespread in Erwinia carotovora: facile trans activation by the carR transcriptional regulator

Bacterial predation of a fungal wheat pathogen: Prelude to experimental evolution of enhanced biocontrol agents

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