Development of limiting dilution viability pcr method to assess the effectiveness of selected biocides to treat indoor fungi growth
Indoor fungal contamination should be treated with cost-effective and green methods. Biocides have direct biological effect on living organisms but the evidence on their control of indoor fungal contamination is scarce. Using conventional cultivation to evaluate their effectiveness is time consum...
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| Format: | Thesis |
| Language: | English English English |
| Published: |
2019
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| Subjects: | |
| Online Access: | http://eprints.uthm.edu.my/60/1/24p%20ER%20CHING%20MING.pdf http://eprints.uthm.edu.my/60/2/ER%20CHING%20MING%20COPYRIGHT%20DECLARATION.pdf http://eprints.uthm.edu.my/60/3/ER%20CHING%20MING%20WATERMARK.pdf http://eprints.uthm.edu.my/60/ |
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| Summary: | Indoor fungal contamination should be treated with cost-effective and green methods.
Biocides have direct biological effect on living organisms but the evidence on their
control of indoor fungal contamination is scarce. Using conventional cultivation to
evaluate their effectiveness is time consuming while polymerase chain reaction (PCR)
provides a fast and reliable alternative. The incorporation of serial dilution technique
and viability information in PCR has made it suitable to evaluate the effectiveness of
biocides. Thus, this study aimed to assess the antifungal ability of biocides, zinc
salicylate (ZS), calcium benzoate (CB) and potassium sorbate (KS) to treat indoor
fungal contamination through developing limiting dilution viability PCR (vPCR).
These biocides were selected as they successfully controlled the growth of indoor
waterborne fungi previously. Indoor air sampling revealed that higher educational
building of computer studies (Building A) and of civil engineering studies (Building
B) were contaminated by 509 CFU/m3 and 805.7 CFU/m3 of indoor airborne fungi,
respectively. Two indoor fungi, Talaromyces spp. and Aspergillus niger were
identified. They were subjected to biocides-treatment and subsequent conventional
cultivation and limiting dilution vPCR due to their potential risks against humans’
health. The limiting dilution vPCR was developed by incorporating the pre-treatment
of propidium monoazide (PMA) before deoxyribonucleic acid (DNA) extraction and
the serial dilution of the DNA template in PCR. This approach was proven to
effectively enumerate the effectiveness of biocides to treat indoor fungi. KS was
shown to have the best effectiveness (100%) to prevent the growth of Talaromyces
spp, followed by ZS (80.8%) and CB (no effect). KS also showed the best
effectiveness against A. niger (100%) at the early stage of the study but its effect
reduced with time. ZS showed durable effect (66.67%) against A. niger Day 9
cultures. Inconstant results were indicated by cultivation method. This study has
provided a cheaper, more accurate and suitable approach to determine the
effectiveness of treatment of indoor fungi than cultivation methods. |
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