Phosphatase Activity Index Research Articles

Potential of phosphatases for express assessment of self-purification at different types of pollution in running waters

Abstract The potential of an express enzymological indicator – phosphatase activity index (PAI) – for assessment of different types of pollution and self-purification potential in running waters was evaluated for three river subcatchments, representative for different ecological situations and impacts. According to the values of correlation coefficients, a significant positive correlation existed among PAI and total microbial count, organic loading and phosphate concentrations. The enzyme activity is useful tool for early identification of risks from point discharge of different wastewaters (treated or non-treated). The role of PAI as an indicator is significant at case of disinfection after treatment of wastewaters in treatment plant – the aquatic microbial community at the discharge point is suppressed but not at a functional level. The results allow classical microbiological and chemical parameters (state variables) to be related directly to the dynamics of the transformation processes by functional variable – PAI.

Risk Modelling of Organic Pollution in Lake Sediments

A risk situation of organic pollutants accumulation in the sediments of the dams from Cascade “Middle Iskar” (NW Bulgaria) is simulated in the present study. The aim is risk modelling of organic pollution in lake sediments and on base of the investigated key chemical and enzymological parameters to risk assessment. A model process in lab scale with addition of whey as a source of organic pollutants was simulated. Two situations near to real conditions were studied: 1) at a decreased concentration of organic pollutants (chemical oxygen demand was 0.265 gO2.kg-1) in the case of discharge of sediments downstream of the river (control situation); 2) at an accumulation of organic pollutants (chemical oxygen demand was 1.463 gO2.kg-1) in the sediments (risk event). The dynamics of chemical oxygen demand (COD), concentration of proteins and lactose as well as of the key enzymological indicators (phosphatase activity index—PAI, anaerobic dehydrogenase activity, protease and ?-galactosidase activities) were investigated. The data from Risk Assessment showed that there is a hazard from higher protein concentration at the end of the process in comparison with the control situation. The risk about COD and lactose concentration during the risk modelling was acceptable. The obtained results showed that the PAI can be used as an indicator for early warning of the organic pollution with protein nature.

A Large-Scale Identification of Sediment-Associated Risks of Contamination with Heavy Metals and Organics: Indicators and Algorithms

As mediators in key biotransformation processes, the complex enzyme activities (measured as a total of extracellular and intracellular activity on sub-organism, organism and supra-organism level) have a high potential to be used as reliable indicators for risk identification in co-contaminated sediments with organics and heavy metals. Two enzyme activities—dehydrogenase activity (TTC-DHA) and phosphatase activity index (PAI) were measured by use of methods with tetrazolium chloride and p-nitrophenyl phosphate in polluted sediments of Middle Iskar River part, Bulgaria. The environmental state of river sector has been strongly influenced by the organics, nutrients, xenobiotics pollutants and by the intensive hydrotechnical activity for construction of 9 micro-hydro power plants. The change of hydrological regime was a factor for intensive sediment accumulation and concentration of pollutants in the area of the cascade. Data for total activities of dehydrogenases and phosphatases in sediments were compared with total count of culturable sediment bacteria and pollutants concentrations. The results showed that the enzyme activities correlated positively with bacterial abundance in sediments and organics content in sediments and negatively with concentrations of xenobiotic pollutants (heavy metals). This approves a high potential of enzyme indicators for regulation of ecosystem self-purification capacity and for early assessment of sediment-associated risks of co-contamination. The correlative relations allow dividing the mathematical algorithms for control and management of processes in technologically influenced hydroecosystem.

CYANOBACTERIAL BLOOMS AND THEIR TOXICITY IN VOJVODINA LAKES, SERBIA

The presence of cyanobacteria (blue-green algae) is a significant indicator of water quality,having in mind that several genera have the quality of producing cyanotoxins, which are harmful to animals,plants and humans. Seven lakes in Vojvodina (Republic of Serbia) were examined in May and September 2007 for cyanobacterial presence and cyanotoxins content, Chl a concentration and index of phosphatase activity as the indicators of water quality. In the spring period, cyanobacteria species were not dominant in only 2 of 14 water samples. Microcystins were detected in all of the lakes examined. The concentrations of microcystins ranged from 6.66 μg/L (Provala Lake) to 199.9 and 238 μg/L (Palic and Ludas Lake respectively).The investigations conducted on 7 water ecosystems in Vojvodina, regarding the basic parameters of eutrophication, Chl a concentration and phosphatase activity index, have rendered the examined ecosystems immensely endangered due to significant water quality deterioration. It was determined that the intensification of eutrophication processes has been linked to the increased presence and abundance of cyanobacteria as well as significant toxin production.

Seasonal variations of microbiological parameters of water quality of the Velika Morava river Serbia

In this study, we investigated the level of sanitary pollution and organic contamination of the Velika Morava River, the largest river in central Serbia. Samples of water for microbiological analysis were collected at 5 sites, monthly, from April 2010 to February 2011. Sanitary analysis, i.e. enumeration of total and fecal coliforms and intestinal enterococci, indicated moderate to critical fecal contamination, while organic load assessment (oligotroph to heterotroph ratio, index of phosphatase activity) revealed the category of moderately polluted water. We also investigated seasonal variations of these groups of bacteria and the factors that could contribute to these differences. Our results showed that the micro- biological quality of the water in the Velika Morava River during different seasons is affected by numerous factors such as unequal loading of wastewaters, solar irradiation, and relations of flow/dilution and rainfall/runoff.

The anthropogenic impact on water quality of the river Danube in Serbia: Microbiological analysis and genotoxicity monitoring

The aim of this work was to examine the impact of urban wastewaters on the water quality of the Danube River in Serbia. Samples of water and sediments for microbiological analysis and genotoxicity monitoring were collected from 6 sites during spring and/or autumn 2010. Sanitary analysis, i.e. enumeration of total and fecal coliforms and intestinal enterococci, indicated moderate to critical fecal contamination, while organic load assessment (oligotroph to heterotroph ratio, index of phosphatase activity) revealed the category of moderately polluted water. Mercury-resistant bacteria were detected in all water samples, with high numbers at locations positioned downstream of Belgrade. There was no correlation of the microbiological parameters of the sediment and water samples. Genotoxicity monitoring, performed by the comet assay on hemocytes of mussels Sinanodonta woodiana, indicated a significant increase of DNA damage in mussels collected from the studied sites compared with the control group.

Geographical and biological analysis of the water quality of Bovan Lake, Serbia

In this work we performed a complex geographical analysis of the Bovan Lake basin, Serbia, as well as an analysis of the physical, chemical and biological parameters of water reservoir during a one-year period. The basic sanitary characteristics and physical, chemical and biological parameters, necessary for understanding locality conditions, were studied, and the saprobity index, class of quality, index O/H, degree of saprobity, degree of trophicity and category based on the phosphatase activity index (PAI), were determined. Our results classify the ecosystem as polytrophic. The degree of saprobity is oligosaprobic - beta mesosaprobic, with a catarobic degree in winter, classifying the water as III - IV class of quality. Due to the presence of organic residues, a domination of heterotrophic bacteria in comparison to oligotrophic bacteria is evident. The ability of autopurification is weak. The results indicate the need for continual monitoring of the water quality and environmental protection of Bovan Lake.

Microbial Response to Accidental Organic Pollution in Selected Part of Iskar River

ABSTRACTThe assessment and control of water quality changes in upper part of Iskar River are important elements for application of complex strategy for management of Iskar Reservoir—the main drinking water source of Sofia city. The most critical factor with potential high risk level for formation of water quality in this river sector is the discharge of ineffectively treated wastewaters from Samokov WWTP and untreated sewages from the small villages. The adequate ecosystem response to this organic pollution is based on the self-purification capacity of the river and the advisable functional structure, activity and metabolism of the microbial communities. During the study period one significant deterioration in water quality has been registered in February 2004. The analyses of hydrochemical parameters showed an organic pollution in river waters below the WWTP influx. This impact activated the self-purification capacity of river ecosystem and the key microbial communities responded with changes on structural and functional levels. The six-fold increase in the number of heterotrophic and coliform bacteria was observed in river channel but at some distance downstream. In the discharge point, the first reaction of the biocenoses was presented on enzymatic level by the significant enhancement in the values of total dehydrogenase activity and the phosphatase activity index. The obtained results for functional microbial response to accidental organic pollution are a good base to formulate bioalgorithms for control and management of water quality and self-purification capacity of Iskar River ecosystem in similar risk situations.

Structural and Functional Changes in River Microbial Communities After Dairy Wastewater Discharge

ABSTRACTThe introduction of an integration approach for management of the water basins, including assessment and control of stream water quality and sediment quality, as well as regulation of the pollutant influx in the water receiver, is necessary. The changes in the microbial communities, as a response to the chronic discharge of untreated dairy wastewater, were followed in river and in depth, in three river components “stream water—sediment water—sediments”. The water quality of Leva River decreased after dairy wastewater discharge as the microbial communities reacted with structural and functional changes, related with enhancement of aerobic heterotrophs and the values of total dehydrogenase activity and phosphatase activity index. The result was a decrease of organic matter and nutrients in the stream water in Station 4. However, an improvement of river water quality was not ascertained according to the Bulgarian State Standard. The applied ecological theory for r/K- strategists showed that in the stream water the microbial community is presented with fast growing populations, while in the sediment water and sediments prevailed slow growing bacteria. In the sediments aerobic heterotrophs were with higher density and showed higher activities of total dehydrogenase, phosphatase and protease. The obtained results confirmed that microbial community in the sediment zone is an important factor for the regulation of the transformation processes of organic matter and nutrients in water and sediments, as well as for the formation of river water quality in water receiver.

MESURE DE L’ENDURCISSEMENT AU FROID ET DE LA VIABILITE DES PLANTES EXPOSEES AU GEL PAR LE DOSAGE DES PHOSPHATASES ACIDES LIBRES

Cellular freezing induces leaking of non-specific acid phosphatase enzymes (EC. 3.1.3.2) from the cell walls of wheat crowns into the liquid medium surrounding the plant tissues. Those free enzymes leak both in the disorganized cytoplasm and in the external medium surrounding the tissues. The phosphastase activity index, measured in the external medium of the frozen plants as compared with the one of the non-frozen plants, decreases proportionally with the temperature of the freezing test until a minimum plateau is reached corresponding to the killing temperature of the plants. The determination of this phosphatase activity index can be used therefore as a quantitative method for the estimation of the viability of plants exposed to freezing. The initial drop of the phosphatase activity index precedes the viability loss as measured with the regrowth tests. The solubilization of those acid phosphatases previously bonded to the cell walls is one cause of the plant death rather than its consequence. The differentiating degrees of cold hardiness can be calculated from the changes in the phosphatase activity during a programmed freezing test among cultivars or species, immediately after running the test. Kharkov (Triticum aestivum L.) sampled in the fall shows + 13 °C differential of cold hardiness as compared with the one sampled in summer while Champlein (Triticum aestivum L.) has developed + 5 °C differential of cold hardiness. In the same conditions, another species (Medicago sativa L. cv. Saranac) shows − 9 °C differential of cold hardiness as compared with Kharkov. Temperatures near the freezing point stabilize instantly the attachment of enzymes to cell walls. This molecular rearrangement, at the enzymatic level, is related to the initial metabolism of cold hardening.