Biopolymers fighting mould

Only few people know that mould not only affects the appearance of furniture and walls, but also damages very strong materials. Moreover, mould can cause allergy and chronic diseases, including oncological ones.

The hazard of mould is aggravated by its ubiquity. Neither cold, nor heat, nor high atmospheric pressure, nor increased radiation level can damage mould fungi Mould fungi can be found in all regions of the Earth. Following men, mould even managed to get to the outer space.

Fungi in the orbit

Mould fungi were first discovered in 1980 in the inhabited modules of the Salut-6 orbiting station. Five years later mould fungi were found in the Salut-7 orbiting station, this time they penetrated the cables in the working module.

In several places mycelium covered as much as 50 % of the surface. Some of the materials were partly damaged by the microorganisms. During the 5th mission to the Mir orbiting station the ultra-strong glass in the navigation porthole of the Soyuz transport spaceship connected to the Mir station was permeated with mould. During the 24th expedition to the Mir station the control unit of the communication equipment went out of order: mould fungi damaged the isolation tubes and terminal blocks. This, in turn, caused oxidation of the copper wires. Nowadays microorganism colonies continue their destructive activity at the International space station.

Aspergillus and penicillium are advancing

Researchers have identified about 250 microorganisms of terrestrial origin living in manned orbiting spacecraft.

Mould fungi favour the locations with high humidity: balconies, window lattices, and wooden structures. Recently several cases of large-scale damage of walls and floors of different buildings caused by mould fungi have been found.

Fungi of the Aspergillus and Penicillium genuses are the most common reason for the decay of materials. They damage all natural materials and most of the artificial ones, even steel and reinforced concrete structures. Some of the materials loose strength, in others relative deformation at the breaking point, as well as module of elasticity and stress vs. deformation ratio decreases. In some cases dielectric properties degrade.

Fungi damage relatively new constructions (built only several years ago) as well as old buildings. In some cases more than 40 types of fungi have been found on the concrete surfaces.

The hazard is greatest for the materials containing substances, which fungi can feed upon, namely, fabrics made of natural fibres, wooden filling materials, protein glues, hydrocarbons, photo and cinema films, paper documents, and, of course, foodstuffs. However, the materials inedible for the fungi are not safe, either. The chemically aggressive metabolites of the fungi can destroy them, too.

Another implication is that mould increases materials humidity. This, in turn, can cause intensive multiplication of bacteria including pathogenic ones (apart from the mould fungi themselves). Therefore foodstuff contamination with mould not only causes degradation of outward appearance and gustatory quality of the products but can also cause food poisoning, disbacteriosis, and metabolism derangement.

According to the data of the World Health Organisation, more than 10 % of the food and fodder becomes unusable due to mould fungi contamination.

Fungi themselves also pose a direct hazard to human health. Spores and fragment of fungi introduced into respiratory tracts can cause allergic diseases such as rhinitis and bronchial asthma (in case of the organisms susceptibility to such diseases). Allergy to the mould fungi occurs among 57 % of rhinitis patients and among 78 % of bronchial asthma patients.

The number of men susceptible to allergy caused by mould increases every year. Allergenic properties have been established in fungi belonging to ca. 300 genuses. However, this number can be obviously much greater. Fungi of genus Aspergillus are the most dangerous ones.

Reduced immunity makes people susceptible to pulmonary aspergillosis, an allergic bronchopulmonary disease caused by the spores of Aspergillus fungi. The spores of such fungi also contain aflatoxin, highly toxic compound that can cause hepatic cancer.

Perfect weapon

The principal way to prevent mass propagation of bacteria and fungi in construction materials is to provide conditions unfavourable for their reproduction. Nowadays one of the techniques for prevention of fungus microflora in engineering structures and for enhancement of sanitary and hygienic state of the premises is ensuring the biocidal properties of the structural materials.

The Institute of Ecotechnologies (IET) has developed chemicals based on biocidal polymers (Biopag, Phosphopag) which were proven to be effective disinfectants for suppression of fungi development both on various surfaces and in air.

These chemicals have a wide range of antimicrobial activity: bactericidal, virucidal, algaecidal, and fungicidal. They have a remarkable set of consumer-friendly features: they are not toxic, have no odour, cause no allergy, and retain their properties at temperatures up to 200? C.

Due to their polymeric structure, these chemicals have a long-term activity. They form a thin impalpable film on the surface of the treated objects that ensures a long-term biocidal protection.

The experts believe the new generation disinfectants to be the most effective means against mould fungi.

Biocidal chemicals Biopag and Phosphopag are certified for application as bactericidal and fungicidal additives in production of concretes, and also for use as independent agents for protection and disinfection of surfaces of engineering structures, buildings, etc., contaminated with mould fungi.

Organosoluble varnish Septopag developed by the IET forms a waterproof biocidal film on the treated surface that suppresses mould fungi growth within the material. This varnish coating is able to provide a long-term antimould and antibacterial protection.

Logosept Company has performed comprehensive studies of fungicidal activity of polymeric disinfectants developed by the IET. The tests have been performed in collaboration with the experts from the A.N. Sysin Institute for Human Ecology and Environmental Hygiene, Research institute of Concrete and Reinforced Concrete, 26th Central Research institute of the Russian Ministry of Defence, and Moscow university for applied biotechnology.

One of the outcomes of these studies is the creation of the Centre for mould prevention based on the Logosept private company.

Concern for human health, quality of products, safekeeping of raw materials, and protection of buildings and engineering structures from biodestruction are the basic components of the Centres activities.

The Centres experts are engaged in a wide range of activities including laboratory analysis of air and surface probe samples, conducting research and organising seminars, distribution of fungicides, organisation of antifungal treatment, and development of specific recommendations for solving the mould problem at various facilities.

The Centre uses in its activities and distributes polymeric bactericidal and fungicidal chemicals created by the IET, including bactericidal paints with a long-term bactericidal effect.

These polymeric chemicals are used in a series of institutions of the Moscow Committee for health care, in the Moscow underground (Metro), in food industry and housing and communal facilities, child-care and educational institutions in Moscow and in Moscow region. Unique results have been obtained during the application of these polymers, thus proving their high efficiency and safety.

Alexander DITYUK, Ph.D (physics).

Deputy Director,

Institute of Ecotechnologies

Andrey MIKHIN

Director,

Private Company Logosept (Moscow)

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