Periodic Reporting for period 1 - PHYCOCYP (PHYtoplankton responses to organic COntaminants: the role of CYtochrome P450)
Reporting period: 2021-09-01 to 2024-08-31
Chemical pollution of natural waters has become a major public concern. Millions of tons of synthetic organic chemicals (OCs) are used annually for industrial, agricultural and consumer’s purposes. These compounds partially find their way to the aquatic environment affecting water quality with consequences for aquatic life. Adverse outcomes of OCs on the biota are directly linked to the ability of the organism to face the toxic insult. Organisms dispose of different defense strategies to deal with OCs and to detoxify those accumulated within their body. Among the multiple detoxification strategies, biotransformation plays a prominent role. Investigation of biotransformation activities has now reached recognized importance in ecotoxicology, providing mechanistic information on the toxic action that OCs may have on the biota. Furthermore, biotransformation studies indicate to what extent organisms may contribute to the fate of OCs in the ecosystems. Transformation products (TPs) generated by organism’s metabolism can be released in the natural environment or enter the food chain, multiplying the number of molecules with anthropic origin in natural ecosystems. Today, the scientific community and policy makers agree on the necessity to include TPs in chemical pollution monitoring and risk assessment for proper environmental protection. Finally, deeper knowledge on biotransformation pathways is required for optimization of pollution removal during waste water treatment processes.
In line with the scientific and societal needs, the general aim of the PHYCOCYP project was to get a mechanistic understanding of the biotransformation processes and their role in phytoplankton tolerance to organic contaminants.
The project focused its research on a group of enzymes, the Cytochrome P450 (CYP), that play a prominent role in biotransformation in higher organisms but that were underexplored in phytoplankton. Phytoplankton are aquatic photosynthetic microorganisms that play a key role in the water food chain and global nutrient cycling, contributing to about half of global primary productivity and being a major sink of carbon dioxide in oceans. Chemical pollution due to anthropogenic activities may considerably affect phytoplankton with consequences on biogeochemical cycling and food chain dynamics. Investigations of OCs biotransformation in phytoplankton is of fundamental importance to improve our understanding of phytoplankton stress responses to contaminant pollution and better assess OCs impact on aquatic environments.
The objectives of the proposed research were i) to investigate the possible role of CYPs as biomarker of OC exposure in phytoplankton, ii) to gain a mechanistic insight in CYP mediated stress responses and biotransformation processes.
To reach this goal the work was organized in three work packages (WPs) that included research and training activities. An integrated multidisciplinary approach was adopted thanks to multiple collaborations with ecotoxicologists, analytical chemists, ecophysiologists and phytoplankton biologists.
The research activities conducted in the PHYCOCYP project indicated that CYPs in phytoplankton are involved in contaminants biotransformation processes. The concentration and composition of diclofenac transformation products were altered in cells treated with CYP inhibitors indicating that CYPs are involved in diclofenac biotransformation pathways. However, CYP genes expression was not directly regulated by OC exposure. CYP activity, besides being important for detoxification via biotransformation processes, resulted to have a role in other stress response pathways (e.g. oxidative stress responses). As a consequence, CYP genes expression cannot be used as a robust biomarker of contaminants exposure in phytoplankton.
In line with the scientific and societal needs, the general aim of the PHYCOCYP project was to get a mechanistic understanding of the biotransformation processes and their role in phytoplankton tolerance to organic contaminants.
The project focused its research on a group of enzymes, the Cytochrome P450 (CYP), that play a prominent role in biotransformation in higher organisms but that were underexplored in phytoplankton. Phytoplankton are aquatic photosynthetic microorganisms that play a key role in the water food chain and global nutrient cycling, contributing to about half of global primary productivity and being a major sink of carbon dioxide in oceans. Chemical pollution due to anthropogenic activities may considerably affect phytoplankton with consequences on biogeochemical cycling and food chain dynamics. Investigations of OCs biotransformation in phytoplankton is of fundamental importance to improve our understanding of phytoplankton stress responses to contaminant pollution and better assess OCs impact on aquatic environments.
The objectives of the proposed research were i) to investigate the possible role of CYPs as biomarker of OC exposure in phytoplankton, ii) to gain a mechanistic insight in CYP mediated stress responses and biotransformation processes.
To reach this goal the work was organized in three work packages (WPs) that included research and training activities. An integrated multidisciplinary approach was adopted thanks to multiple collaborations with ecotoxicologists, analytical chemists, ecophysiologists and phytoplankton biologists.
The research activities conducted in the PHYCOCYP project indicated that CYPs in phytoplankton are involved in contaminants biotransformation processes. The concentration and composition of diclofenac transformation products were altered in cells treated with CYP inhibitors indicating that CYPs are involved in diclofenac biotransformation pathways. However, CYP genes expression was not directly regulated by OC exposure. CYP activity, besides being important for detoxification via biotransformation processes, resulted to have a role in other stress response pathways (e.g. oxidative stress responses). As a consequence, CYP genes expression cannot be used as a robust biomarker of contaminants exposure in phytoplankton.
The toxicology of 3 different organic contaminants (the herbicide diuron and two pharmaceutical products, diclofenac and ethynil estradiol) were tested on phytoplankton species. Research activity particularly focused on the model diatom specie Phaeodactylum tricornutum. CYP genes expression was investigated in parallel to effects on cell physiology and cellular stress responses (transcriptomic via RNA-seq). Role of CYPs in OC metabolism was investigated using state of the art mass spectrometric (MS) methods and the comparative analysis of OC biotransformation was conducted in control cultures and CYP inhibited cultures.
Results obtained in PHYCOCYP project indicated that diatoms may use different detoxification pathways to respond to different organic contaminants exposure. Transcriptomic analysis provided interesting information with respect to the stress response strategies operated by the diatom to deal with the three different organic contaminants. Detoxification via sequestration seemed to be the main response associated to Ethynil Estradiol exposure. On the other hand, biotransformation processes were identified in the Diclofenac exposed cultures and CYP enzymes were resulted to be involved in these processes.
These results were presented to the academic community, policy makers and industry sector via participation to international conferences, workshops, seminars and working groups.
Multiple dissemination activities targeting the general public and society were conducted during the project in order to raise awareness about the impact of organic contaminants on marine environments and the possible actions that can be implemented in order to cope with chemical pollution.
Results obtained in PHYCOCYP project indicated that diatoms may use different detoxification pathways to respond to different organic contaminants exposure. Transcriptomic analysis provided interesting information with respect to the stress response strategies operated by the diatom to deal with the three different organic contaminants. Detoxification via sequestration seemed to be the main response associated to Ethynil Estradiol exposure. On the other hand, biotransformation processes were identified in the Diclofenac exposed cultures and CYP enzymes were resulted to be involved in these processes.
These results were presented to the academic community, policy makers and industry sector via participation to international conferences, workshops, seminars and working groups.
Multiple dissemination activities targeting the general public and society were conducted during the project in order to raise awareness about the impact of organic contaminants on marine environments and the possible actions that can be implemented in order to cope with chemical pollution.
PHYCOCYP research activity started to uncover an underexplored field of research related biotransformation processes in phytoplankton. Generated results represent an important source of information for the scientific community and for future research directions in the field of phytoplankton stress biology and detoxification strategies.
In a biotechnological context, biotransformation rates observed in the model diatom P. tricornutum, were not competitive with respect to those reported for other microorganisms. However, it cannot be excluded that other phytoplankton species that evolved a larger CYP gene diversity, may be more efficient in contaminants biotransformation. The work carried out in the PHYCOCYP action is not expected to have direct impact on industrial applications for contaminants detoxification processes, but it represents a starting point for deeper investigation in the biotechnological field.
In an ecotoxicological context, results obtained are relevant to address environmental issues related to pollution associated to organic contaminants released with anthropic activities. Results from this action will have a long-term impact on the scientific community and will help policy makers define strategies for environmental protection.
In a biotechnological context, biotransformation rates observed in the model diatom P. tricornutum, were not competitive with respect to those reported for other microorganisms. However, it cannot be excluded that other phytoplankton species that evolved a larger CYP gene diversity, may be more efficient in contaminants biotransformation. The work carried out in the PHYCOCYP action is not expected to have direct impact on industrial applications for contaminants detoxification processes, but it represents a starting point for deeper investigation in the biotechnological field.
In an ecotoxicological context, results obtained are relevant to address environmental issues related to pollution associated to organic contaminants released with anthropic activities. Results from this action will have a long-term impact on the scientific community and will help policy makers define strategies for environmental protection.