Biodeterioration

All kinds of microbes, including Aspergillus, contribute actively to geological phenomena. Central to many such geomicrobial processes are transformations of metals and minerals. Biodeterioration is the branch of science which focuses upon microbial transformations of compounds, especially the undesirable changes of man-made materials via processes including mineral formation, dissolution or deterioration. Aspergillus spp. can colonise and damage multiple materials, including: woods, metals, polymers, stone and fuels. This fungus has been associated with a reduction in both stability and durability of man-made structures and materials e.g.

  • Concrete housing of nuclear waste disposal units
  • Structural components of bridges
  • Building materials
  • Glass
  • Paper
  • Fuels

Perhaps most worryingly novel research by Fomina et al (2007) has demonstrated that prolonged fungal biochemical activity promotes adverse environmental affects through consequential damage of nuclear waste disposal units. This deterioration occurs despite the high radioactivity, as fungi are able to successfully colonise concrete and induce deterioration both biochemically and biomechanically in these conditions (Zhdanova et al. 2000, Fomina et al. 2007). Fungal hyphae may directly induce damage by physical perforation and tunneling in decaying rock formations (Formina et al. 2007). Fungi may excrete organic compounds which degrade materials, referred to as (bio)chemical dissimilatory biodeterioration (Allsopp et al. 2004). Therefore, one of the primary concerns is that without adequate maintenance or treatment to waste disposal units, environmental leakage of highly radioactive substances may result. A recent study of the inner concrete of the Chernobyl reactor found that Aspergillus species to be one of the most prevalent fungal species (Zhadanova et al. 2016). Turick and Berry (2016) stated that

‘the microbial contribution to degradation of the concrete structures containing radioactive waste is a constant possibility. The rate and degree of concrete biodegradation is dependent on numerous physical, chemical and biological parameters’.

Further supporting Aspergillus’ involvement in biodeterioration , Zlobenko (2013) highlighted that Aspergillus niger had the greatest capacity for the biodeterioration of concrete nuclear waste containment units.

Colonisation and biogradation of concrete is seen on many modern building materials, bridges, buildings and monuments (Lugauskas and Jaskelevicus. 2007, Geweely. 2010, Piotrowska et al. 2014, Farooq et al. 2015) with similar potential for disastrous consequences and loss of heritage.

Aspergillus and other fungi have been identified on the orbiting International Space Station (ISS). With over thirty seven strains of fungi isolated, one of the most prevalent was found to be Aspergillus (Satoh et al. 2016). These fungi are strongly associated with the degradation of polymers (Lugauskas et al. 2004) and other materials on which the structure of the ISS depends and therefore may be a real danger to system failure through biodeterioration.

Biocorrosion is defined as the enhanced degradation of substances through microbial interactions. Aspergillus has been demonstrated to mediate biocorrosion in metal, wood, oil and clay containing structures (GADD. 2010). One of the primary enabling mechanisms through which biodeterioration occurs is via fungal biofilm formation. This is defined by the clustering of surface-bound microbial cells that are encapsulated in an extra-cellular macromolecular matrix (Donlann. 2002). Biofilm formation involves the production of acidic substances and pigments, which can directly damage the integrity of structures and is associated with the degradation of hydrocarbon containing compounds (Morton and Surman. 1994). The extent to which this happens is varied and may be unclear for given sites. Uniquely differing environmental conditions, diversity and concentrations of organisms on structures, makes it  increasingly difficult to determine the extent to which deterioration occurs on untested sites (Saiz-Jimenez, 2000).

Prevention of biodeterioration

Numerous protective compounds have been developed to aid in both the prevention and the treatment of biodeterioration. Rajkowska et al (2016) indicated that quaternary ammonium biocides (QAC’s) may be highly beneficial in protecting both wood and brick from 6 different moulds, including Aspergillus. Other preventative measures include the use of antifungals in cement mortars, ozone application on concrete and ZnO-based nanocomposites, specifically designed to mitigate fungal induced corrosion (Do. 2005; Ditaranto. 2015). Thus, the use of these compounds may negate or slow biodegradation by inhibiting biofilm formation on structural materials.

Bioremediation

Bioremediation is the deliberate application of microorganisms for reclamation, immobilization or detoxification of metallic and radionuclide pollutants. Santos et al (2014) demonstrated the bioremediatory effects of Aspergillus awamori and its ability to degrade the toxic components of cyanide-containing wastewater. The innate capacity of Aspergillus terreus to degrade contaminants such as Endosulfan – a known insecticide – has also been identified (Mukherjee et al. 2005). Furthermore, the bioremediatory potential of A. niger has been established in the removal of cadmium – a toxic heavy metal – from soil (Srivastava and Thakur, 2006). Impacts on human & animal health Fungal spores & other hyphal debris are known to cause respiratory health problems when inhaled. The growth of Aspergillus and other fungi on building materials in the home and offices is often noted as a source of airborne spores – see Air Quality section for more details. The prevention of growth of fungi within our homes, places of work & recreation may be highly beneficial in reducing these respiratory health effects (Benndorf et al. 2008).

Biocides are chemical agents with the capability of destroying living organisms – pathogenic and non-pathogenic (Block. 2001). Thus they have numerous applications: Sterilizer, Tuberculicide, Disinfectant, Fungicide, Virucide, Sanitiser (Rossmore. 2012). Tortarano et al (2005) demonstrated Aspergillus fumigatus to be susceptible to biocidal activity of commonly used biocides within a hospital setting. However, it has also been indicated that biocides may enhance growth of some toxigenic species – Aspergillus westerdijkiae – and be a threat to human health when used in buildings (Mikkola. 2015) and have been applied in certain settings, with limited impact on reducing Aspergillus and other fungal growth. According to the PAN – pesticide action network – estimate at least 10% of all biocides used are known endocrine disruptors and potentially carcinogenic (PAN, 2016).

Silver nanoparticles (AgNP’s) have been developed as an alternate antifungal to biocides and are effective in reducing common indoor mould load (Ogar et al. 2015). Furthermore, the neurotoxic capacity of AGNP’s has been under scrutiny in recent years. Xu et al (2013) produced data that ‘clearly demonstrates the potential detrimental effects of AgNPs on neuronal development and physiological functions and warns against its prolific usage’ in homes and public buildings.

Moulds present within buildings propose a clear health risk to those with asthma and respiratory Allergies, with Aspergillus being one of the most prevalent fungi (Twaroch et al, 2015). Thus, it is clear that precautionary measures need to be adhered to in order to mitigate potential health risks caused by Aspergillus and in doing so, preventing biodeterioration of future constructions. A study evaluating several common antifungals, demonstrated that tea tree oil had the greatest growth inhibitory capacity against A. fumigatus and P. chrysogenum (Rogawansamy et al. 2015). Furthermore, Inouye et al (2000) observed the antifungal potential of several essential oils, showing promising antifungal ability, indicating a possible non- toxic alternative to conventional antifungal solutions for use in enclosed environments.

Reviews

Showing 9 posts of 9 posts found.
  • Title

    Author

    Year

  • Charles E. Turick, Christopher J. Berry

    2016

  • R.P.George, Vinita Vishwakarma, S.S. Samal and U Kamachi Mudali

    2019

  • Little B, Ray R

    2011

  • Gaylardea CC, Morton LHG

    1999

  • G. M. GADD

    1993

  • Burgstaller W, Schinner F

    1993

  • Beech IB, Gaylarde CC

    1999

  • Adeyemi AO, Gadd GM.

    2005

  • Wei, SP. Jiang, ZL. Liu, H. Zhou, DS. Sanchez-Silva, M.

    2013

Reviews (external sources)

Diercks, M., Sand, W. and Bock, E. (1991) ‘Microbial corrosion of concrete’, Experientia, 47(6), pp. 514–516. doi:10.1007/bf01949869. Springer

Bibliography

Showing 10 posts of 26 posts found.
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  • Xu F, Piett C, Farkas S, Qazzaz M, Syed NI.

    2013

  • Shaili Srivastava & Indu Shekhar Thakurb

    2006

  • Charles E. Turick, Christopher J. Berry

    2016

  • L.H.G. Morton, S.B. Surman

    1994

  • Mikkola R, Andersson MA, Hautaniemi M, Salkinoja-Salonen MS.

    2015

  • Inouye S, Tsuruoka T, Watanabe M, Takeo K, Akao M, Nishiyama Y, Yamaguchi H.

    2000

  • M. Fomina , V. S. Podgorsky , S. V. Olishevska , V. M. Kadoshnikov, I. R. Pisanska , S. Hillier & G. M. Gadd

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  • Donlan RM.

    2002

  • Farooq M, Hassan M, Gull F

    2015

  • Lugauskas A, Prosychevas I, Levinskaite L, Jaskelevicius B.

    2004

Bibliography (external sources)

Allsopp, D., Seal, K.J. and Gaylarde, C.C. (2004) Introduction to Biodeterioration. United Kingdom: Cambridge University Press. Available at Amazon

Block, S.S. (2001) Disinfection, sterilization, and preservation. Available at Amazon  (Accessed: 10 August 2016).

PAN Germany – Pesticide Action Network Germany, The draft biocide regulation is not enough to adequately protect human and the environment, Flyer, 2010, pp.1-2 Available here (Accessed: 10 August 2016).

Rossmoore, H.W. (2012) Handbook of Biocide and preservative use. Available here (Accessed: 10 August 2016).

Slideshow

Zlobenko, B.P. (2013). ‘Assessment of the Biodegradability of Containers for Low and Intermediate Level Nuclear Waste’ (IAEA-TECDOC- CD– 1701(Companion CD)). International Atomic Energy Agency (IAEA) Website


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