Screening of Microorganisms for Biodegradation of Simazine Pollution (Obsolete Pesticide Azotop 50 WP)
Magdalena Baszak
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Robert Peech
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Paulina Graczyk
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R. Peech Institute of Chemical Organic Technology, West Pomeranian University of Technology in Szczecin
, Puaskiego 10, 70-322 Szczecin,
Poland
The capability of environmental microorganisms to biodegrade simazinean active substance of 2-chloro-s-triazine herbicides (pesticide waste since 2007)was assessed. An enormous metabolic potential of microorganisms impels to explore the possibilities of using them as an alternative way for thermal and chemical methods of utilization. First, the biotope rich in microorganisms resistant to simazine was examined. Only the higher dose of simazine (100 mg/l) had an actual influence on quantity of bacteria and environmental fungi incubated on substrate with simazine. Most simazine-resistant bacteria populated activated sludge and biohumus (vermicompost); the biggest strain of resistant fungi was found in floral soil and risosphere soil of maize. Compost and biohumus were the sources of microorganisms which biodegraded simazine, though either of them was the dominant considering the quantity of simazine-resistant microorganisms. In both cases of periodic culture (microorganisms from biohumus and compost), nearly 100% of simazine (50 mg/l) was degraded (within 8 days). After the repeated enrichment culture with simazine, the rate of its degradation highly accelerated, and just after 24 h, the significant decrease of simazine (20% in compost and 80% in biohumus) was noted. Although a dozen attempts of isolating various strains responsible for biodegradation of simazine from compost and biohumus were performed, only the strain identified as Arthrobacter urefaciens (NC) was obtained, and it biodegraded simazine with almost 100% efficiency (within 4 days).
1 Introduction
1.1 Obsolete Pesticides
If microorganisms are used to biodegrade sustained,
toxic pollutants (persistent organic pollutants) to live
organisms (Alexander 1999; Kulkarni and Chaudhari
2006; Nishino and Spain 1993; Oh et al. 2003), it is
also possible to exploit them to neutralize organic
obsolete pesticides. Nowadays, the use of
microorganisms to biodegrade this kind of waste is almost
imperceptible, as the most popular way of managing
with them is thermal utilization (Martnez 2004).
There is, in fact, no alternative for high-temperature
incineration as it is a popular and fast way of
discarding toxic load from the environment, but this
technology also bears many drawbacks. Not only the
pyrotechnical installations can cause local
communities protests but also the high costs of special
shipment and, of course, the incineration itself can
be an obstacle.
Obsolete pesticides can be shortly defined as
stocked pesticides that can no longer be used for
their original purpose or any other purpose and
therefore require disposal. Such pesticides can no
longer be used because their use has been banned,
because they have deteriorated, or because they are
not suitable for the use originally intended and cannot
be used for another purpose, nor can they easily be
modified to become usable (FAO 1995). Obsolete
pesticides, as well as their preceding utilitarian
versions, consist of active substances, that is,
chemical compounds or substances which, while
penetrating natural environment (waters, soil, food web),
modify and harm it, often becoming an ecological
time bomb (Egenhofer and Vijgen 2009).
1.2 Scale of the Problem
Spreading obsolete pesticides in the environment is a
global problem. The scale of the problem varies
depending, of course, on economic situation and
social awareness. In Western Europe countries
(Germany, The Netherlands, Belgium, France) as well as
in the Scandinavian countries, pesticide trade and its
waste management are strictly under control for years
now. In the countries of Central and Eastern Europe
and some countries of Latin America (Chile,
Venezuela, Nicaragua), the efforts to resolve the pesticide
problem legally and effectively seem to bring first
results (Egenhofer and Vijgen 2009). Despite the
efforts, there are places in these countries particularly
burdened with the toxic load, for instance,
postproduction pesticides stock Rudna Gra Poland
about 160,000 tons of waste on 20 ha, are placed on
the list of Hot Spots created by Helsinki
Commission working on protection of the marine environment
of the Baltic Sea (89th place on the list). There are yet
places in developing countries where agricultural
crops are considerably contaminated with pesticide
waste (Ethiopia, Tanzania, Botswana, Mali,
Madagascar) (Dalvie et al. 2006; Martnez 2004; Naidoo and
Buckley 2003). Since Poland joined European Union
in 2004, the plans of hazardous waste management
under European standards have been introduced. The
2010 National Waste Management Plan (Resolution
of the Council of Ministers No. 233 from 29
December 2006) establishes, by 2010, elimination of
burial grounds and stocks of obsolete pesticides as
well as initiation of elimination of hazards (...truncated)