Analysis of Microbial Volatile Organic Compounds (MVOCs)

“Sick Building Syndrome” (SBS) occurs frequently in airtight buildings, but there are also a wide variety of factors that triggers the health problems. Numerous investigations have shown that micro-organisms may play an important role. Studies have shown that there was a high correlation between home dampness indicators and respiratory health problems. There were also indications that volatile organics from microbial cultures has an impact on cilial cells in respiratory airways.

Typically, a musty and earthy odour is the first sign of microbial activity. The microbial activities usually result in the decomposition of complex organic compounds into simpler compounds, and, in so doing, producing a wide range of by-products including the MVOCs. Some of these compounds are unique to micro-organisms; some can be the natural components of building materials that they grow on; and others are the same as common indoor air pollutants. The microbial volatile organics are so diverse that they encompass many chemical classes. In addition, there is no fixed MVOC pattern as the microbial emissions are different depending on the specific species, the substrates and the environment.

Determination of MVOCs is a useful way to check for the presence of mold. In many situations where spores of the micro-organisms are absent, the presence of unique MVOCs can be used to indicate the microbial activities.

Although many MVOCs have been reported in the literature, a lot of them are also known from indoor sources such as furnishings and building materials. In order to distinguish microbial volatiles from other sources, it is of utmost importance to choose compounds that are unique to microbial origin to determine the presence of microbial activities. Currently, other laboratories have used a list of VOCs as markers of the microbial activities, however, more often only a few of them were found in the air sample and the results are not conclusive. When MVOCs are present, there are often a number of higher molecular weight microbial compounds present. The detection of these compounds (listed in Table 2) in conjunction with some of the compounds in the target list will give a clear indication of microbial growth.

Normally, the concentrations of MVOCs in indoor air are very low. The use of a solvent extraction technique will often lead to false negative results. The thermal desorption GC/MS technique offers full scan capability with a thousand-fold increase in sensitivity. Not only can MVOCs be detected, but sesquiterpenes from micro-organisms activities can also be identified. Below is a summary of the method used and the MVOCs/Sesquiterpenes that are targeted for:

Microbial Volatile Organic Compounds Method

• Analytical Method – Thermal desorption/ gas chromatography/mass spectrometry
• Mode – full scan

Data Analysis

• Quantitative analysis of target MVOCs – Table 1
• Qualitative list – Table 2

Table 1 Target MVOC List

Table 2 Qualitative List

References for Microbial Volatile Organic Compounds

1. Sunessn, A. et al. Identification of Volatile Metabolites from Five Fungal Species Cultivated on Two Media. Applied and Environmental Microbiology, Aug 1995 p 2911-2918
2. Karahadian, C. et al. Volatile Compounds from Penicillium sp. Contributing Musty-Earthy Notes to Brie and Camembert Cheese Flavors. J. Agric. Food Chem. 1985, 33, 339-343
3. Vice, A.J., Indentification of Mold Growth in Indoor Environments”, M.Sc. Thesis, Virginia Tech. 2000
4. Halim, A. F. et al. Odorous Constituents of Penicillium decumbens. Mycologia 1975, Vol 67, 1158-1165
5. Bjurman, J., Kristensson, J. Volatile Production by Aspergillus versicolor as a possible cause of odor in houses affected by fungi. Mycopathologia, 1992, 118, 173-178
6. Ezeonu, M., et al. Fungal Production of Volatiles during Growth on Fiberglass. Nov 1994, Vol. 60, 11, 4172-4173
7. Norrman, J. The Influence of Different Nigrogen Sources on the Production of Volatile Compounds by Dipodascus aggregatus. Arch. Mikrobial. 1971, 80, 338-350
8. Seifert, R. M., King, A. D. Identification of Some Volatile Constituents of Aspergillus clavatus. J. Agric. And Food. 1982, 30, 786-790
9. Fischer, G. et al. Exposure to Airborne Fungi, MVOC and Mycotoxins in Biowaste-handling Facilities. Int. J. Hyg. Environ. Health. 2000, 203, 97-104
10. Borjesson, T. et al. Volatile Metabolites Produced by Six Fungal Species Compared with Other Indicators of Fungal Growth on Cereal Grains. Applied and Environmental Microbiology. Aug. 1992, Vol. 58, 8, 2599-2605
11. Korpi, A. et al. Volatile Metabolites of Serpula lacrymans, Coniophora puteana, Poria placenta, Stachybotrys chartarum and Chaetomium globsum. Building and Environment. 1999, 34, 205-211
12. Borjesson, T. et al. Volatile Metabolites and Other Indicators of Penicillium aurantiogriseum Growth on Different Substrates. Applied and Environmental Microbiology. Dec. 1990, Vol. 56, 12, 3705-3710
13. Mattheis, J. P., Roberts, R. G. Identification of Geosmin as a Volatile Metabolite of Penicillium examsum. Applied and Environmental Microbiology. Sept. 1992, Vol. 58, 9, 3170-3172
14. Kaminski, E. et al. Identification of the Predominant Volatile Compounds Produced by Aspergillus flavus. Applied Microbiology. Nov. 1972, Vol. 24, 3, 721-726
15. Kaminski, E. et al. Volatile Flavor Compounds Produced by Molds or Aspergillus, Penicillium, and Fungi imperfecti. Applied Microbiology. June 1974, Vol. 27, 6 1001-1004
16. Norrman, J. A Gas Chromatographic Investigation of the Influence of Different Carbon Sources on the Production of Volitile Comounds by Dipodascus aggregatus. Arch. Mikrobiol. 1971,Vol. 28, 75, 145-162
17. Bjurman, J., Release of MVOCs from Microorganisms in Organic Indoor Air Pollutants: Occurrence –measurement – evaluation T. Saithammer, Ediditor, Wiley-VCH: Weinheim, 1999, p. 259-273
18. Gao, P. et al. Determination of Unique Microbial Volatile Organic Compounds Produced by Five Aspergillus Species Commonly Found in Problem Buildings, AIHA Journ. (63), 2002, p. 135 – 140
19. Wessen, B and Schoeps, K., Microbial Volatile Organic Compounds – What Substances Can Be Found in Sick Buildings? Analyst, 1996 121 1203-1205
20. Karahadian, C. et al. Volatile Compounds from Pencillium sp. Contributing Musty-Earthy Notes to Brie and Camembert Cheese Flavors, J. Agric Food Chem. 1985, 33 339-343
21. Bjurman, J, Kristensson, J., Volatile Production by Aspergillus Versicolor as a Possible Cause of Odor in Houses Affected by Fungi, Mycopathlogia, 1992, 118:173-178