Comparison of effects of sublethal microwave radiation and conventional heating on the metabolic activity of Staphylococcus aureus.

Applied and environmental microbiology · 1980 · Mixed · Low evidence

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MixedLow evidencePaper 6060

Study snapshot

PublicationApplied and environmental microbiology · 1980

Study typeother

Reported directionMixed

Evidence ratingLow

Abstract

This study was conducted in an attempt to characterize some of the effects of sublethal microwave radiation on cells of Staphylococcus aureus. Cultures were exposed to microwave radiation for 10, 20, 30, and 40 s. The effects of a conventional heat treatment were also compared by placing flasks containing cultures in a boiling water bath for the amount of time required to reach temperatures equivalent to those found in cultures exposed to microwave radiation. Control, microwave-treated, and conventionally heat-treated cultures were centrifuged, pellets were resuspended in distilled water, and the resulting suspensions were passed through a French pressure cell. Cell lysates and walls were then isolated and assayed for enzymatic activity. Thermonuclease production was also determined at various levels of exposure of cells to microwave radiation. Activities of malate and alpha-ketoglutarate dehydrogenases, cytochrome oxidase, and cytoplasmic adenosine triphosphatase were higher in microwave-treated cells than in control cells. Membrane adenosine triphosphatase, alkaline phosphatase, and lactate dehydrogenase activities were unaffected when cells were exposed to microwave radiation. The activity of glucose-6-phosphate dehydrogenase was decreased by exposure of cells to microwave radiation. In conventionally heated cells, activities of glucose-6-phosphate and malate dehydrogenases and cytoplasmic adenosine triphosphatase increased activities of alpha-ketoglutarate and lactate dehydrogenases decreased, and alkaline phosphatase activity remained unaffected. Increased levels of thermonuclease activity were observed when cells were exposed to microwave radiation for 10 or 20 s. Data indicate that microwave radiation affects S. aureus in a manner which cannot be explained solely by thermal effects.

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AI evidence extraction

Structured fields below were generated from the paper’s abstract and metadata to make the evidence easier to inspect. Automated extraction may be incomplete or incorrect; verify important details against the original paper.

Study typeother

Effect directionmixed

PopulationStaphylococcus aureus cultures

Sample sizeNot supplied

Exposuremicrowave · 10, 20, 30, and 40 s

Evidence strengthLowConfidence: 74% · Peer reviewed: yes

Main findings

Compared with controls, microwave-exposed S. aureus showed higher activities of malate and alpha-ketoglutarate dehydrogenases, cytochrome oxidase, and cytoplasmic ATPase; membrane ATPase, alkaline phosphatase, and lactate dehydrogenase were unaffected; and glucose-6-phosphate dehydrogenase activity decreased. Conventional heating to equivalent temperatures produced a different pattern of enzyme activity changes. Thermonuclease activity increased after 10 or 20 s microwave exposure, and the authors state the effects could not be explained solely by thermal effects.

Outcomes measured

Enzymatic activity in cell lysates/walls (malate dehydrogenase, alpha-ketoglutarate dehydrogenase, cytochrome oxidase, cytoplasmic ATPase, membrane ATPase, alkaline phosphatase, lactate dehydrogenase, glucose-6-phosphate dehydrogenase)
Thermonuclease production/activity

Limitations

Frequency and dosimetry (e.g., SAR/power density) not reported in abstract
Sample size and replication not reported in abstract
Short exposure durations only (seconds)
In vitro bacterial culture model; generalizability to other organisms/conditions unclear from abstract

View raw extracted JSON

{
  "study_type": "other",
  "exposure": {
    "band": "microwave",
    "source": null,
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": "10, 20, 30, and 40 s"
  },
  "population": "Staphylococcus aureus cultures",
  "sample_size": null,
  "outcomes": [
    "Enzymatic activity in cell lysates/walls (malate dehydrogenase, alpha-ketoglutarate dehydrogenase, cytochrome oxidase, cytoplasmic ATPase, membrane ATPase, alkaline phosphatase, lactate dehydrogenase, glucose-6-phosphate dehydrogenase)",
    "Thermonuclease production/activity"
  ],
  "main_findings": "Compared with controls, microwave-exposed S. aureus showed higher activities of malate and alpha-ketoglutarate dehydrogenases, cytochrome oxidase, and cytoplasmic ATPase; membrane ATPase, alkaline phosphatase, and lactate dehydrogenase were unaffected; and glucose-6-phosphate dehydrogenase activity decreased. Conventional heating to equivalent temperatures produced a different pattern of enzyme activity changes. Thermonuclease activity increased after 10 or 20 s microwave exposure, and the authors state the effects could not be explained solely by thermal effects.",
  "effect_direction": "mixed",
  "limitations": [
    "Frequency and dosimetry (e.g., SAR/power density) not reported in abstract",
    "Sample size and replication not reported in abstract",
    "Short exposure durations only (seconds)",
    "In vitro bacterial culture model; generalizability to other organisms/conditions unclear from abstract"
  ],
  "evidence_strength": "low",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "microwave radiation",
    "sublethal exposure",
    "conventional heating",
    "thermal vs non-thermal effects",
    "Staphylococcus aureus",
    "metabolic activity",
    "enzyme activity",
    "thermonuclease"
  ],
  "suggested_hubs": []
}

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AI-extracted fields are generated from the abstract and metadata and may be incomplete or incorrect. This material is for informational purposes and is not medical advice.

Identifiers and source

DOI: 10.1128/aem.39.1.13-16.1980
PubMed: 6444504

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