Quantitative detection of asbestos fiber in gravelly sand using elastic body-exposure method

Our plain-English summary of Quantitative detection of asbestos fiber in gravelly sand using elastic body-exposure method, by N. Yoshida, K. Takebe (Journal of Industrial Microbiology & Biotechnology, 2006).

The study

• Authors: N. Yoshida, K. Takebe
• Journal: Journal of Industrial Microbiology & Biotechnology
• Published: 2006;33(10):827-33
• Cited by: 2 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Chrysotile or crocidolite colloidal solution containing donor plasmid DNA and Escherichia coli cells was subjected to elastic body friction. These acicular clay minerals mediated E. coli antibiotic resistance plasmid transformation. Other clay minerals had no effect on E. coli transformation. The number of E. coli transformants was counted after elastic body exposure with various crocidolite concentrations. There was a correlation between the number of E. coli transformants and crocidolite concentration (between 40 and 1,000 ng/ml). A mixture consisting of sea sand and crocidolite was utilized as a model for quantitative detection of asbestos in gravelly sand. With sea sand containing 0.15-15 mg of crocidolite, a correlation between crocidolite concentration and the number of colonies derived from E. coli transformants was observed. This indicates that measurement of asbestos is possible even when the asbestos sample includes gravelly sand. Fluorescence microscopic observation of crocidolite colloidal solution indicated that crocidolite was present as spherical aggregates having diameters of 6-9 microm. Thus, the number of transformants correlated with that of 6-9 microm crocidolite aggregates.

In plain English

In this Japanese laboratory study, the authors tested whether bacteria could measure asbestos in sand. They mixed Escherichia coli bacteria, an antibiotic-resistance plasmid (a small piece of DNA) and suspensions of different minerals, then rubbed it across an agar plate. Chrysotile and crocidolite enabled the bacteria to take up the plasmid, giving 200 plus or minus 12 and 210 plus or minus 10 resistant colonies per plate respectively. Bentonite, kaolinite and talc gave none; glass wool, rock wool and magnesium oxide were listed as not detected, though the text says their effects could not be examined. Colony numbers rose with crocidolite concentration between 40 and 1,000 ng/ml. In a model of 1 gram of sea sand containing 0.15 to 15 mg of crocidolite, colony numbers also tracked crocidolite content. The authors concluded that asbestos can be measured this way despite large amounts of other clay minerals, with a detection limit of about 100 micrograms per gram of sea sand. They stated the method is not suitable below that level. They proposed a protocol for building waste but reported no results from real samples.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory experiment developing a detection method (bacterial transformation by 'elastic body exposure'), using a sea sand and crocidolite mixture as a model
• Who was studied: Escherichia coli JM109 bacterial cells with pUC18 plasmid DNA. The model samples were 1-gram portions of washed, sieved sea sand mixed with crocidolite. The work was done at the University of Miyazaki, Japan; the article was received 2005 and published 2006. No human subjects.
• Exposure: Commercial chrysotile and crocidolite reagents. For comparison, bentonite, kaolinite, talc, glass wool, rock wool (from architectural waste) and magnesium oxide were tested. Crocidolite was added to sea sand at 0.15 to 15 mg per gram.
• Main results:
  • Chrysotile gave 200 plus or minus 12 transformant colonies per plate, and crocidolite gave 210 plus or minus 10.
  • Bentonite, kaolinite and talc did not mediate transformation (no colonies detected in Table 1).
  • Glass wool, rock wool and magnesium oxide are listed as not detected in Table 1, but the text states that their effects on gene introduction could not be examined.
  • In water suspensions, the number of transformant colonies correlated with crocidolite concentration between 40 and 1,000 ng/ml. The regression line was y = 0.585x + 49.33, with R2 = 0.926.
  • In the sea sand model (0.15 to 15 mg crocidolite per gram of sand), colony numbers correlated with crocidolite content. The regression line was y = 33.75x + 14.34, with R2 = 0.919.
  • The detection limit was about 100 micrograms of asbestos per gram of sea sand.
  • Scanning electron microscopy showed crocidolite fibers in the suspension measuring 0.05 to 0.12 micrometres in diameter and 0.5 to 3.0 micrometres in length.
  • Under fluorescence microscopy, individual crocidolite particles could not be identified; only large aggregates of 5 to 10 micrometres were seen.
• The authors' conclusion: The authors concluded that quantitative determination of asbestos by the elastic body-exposure method is possible even in the presence of large quantities of other clay minerals.
• Limitations the authors state:
  • The authors stated the method is not suitable for asbestos levels below 100 micrograms per gram.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Chrysotile, Crocidolite.

Medical terms in this study, explained in our Lexicon: Chrysotile, Crocidolite, Acicular.

Related studies

• Earthquakes promote bacterial genetic exchange in serpentinite crevices — N. Yoshida, N. Fujiura (2009)
• Chrysotile asbestos fibers mediate transformation of Escherichia coli by exogenous plasmid DNA — N. Yoshida, T. Ikeda, et al. (2001)
• Escherichia coli cells penetrated by chrysotile fibers are transformed to antibiotic resistance by incorporation of exogenous plasmid DNA — N. Yoshida, K. Kodama, et al. (2002)
• Chestnut bur-shaped aggregates of chrysotile particles enable inoculation of Escherichia coli cells with plasmid DNA — N. Yoshida, Y. Saeki (2004)
• Discovery and application of the Yoshida effect: nano-sized acicular materials enable penetration of bacterial cells by sliding friction force — N. Yoshida (2007)
• Plasmid DNA is released from nanosized acicular material surface by low molecular weight oligonucleotides: exogenous plasmid acquisition mechanism for penetration intermediates based on the Yoshida effect — N. Yoshida, K. Ide (2008)

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