Application of different enzyme assays and biomarkers for pollution monitoring of the marine environment

MCDA-DEA approach to construct a composite indicator for effluents from WWTPs considering the influence of PPCPs

Considering current water situation, reuse is an effective solution to meet water demand and reduce pressure on conventional water sources. However, pharmaceutical and personal care products (PPCPs) in effluents from wastewater treatment plants (WWTPs) decrease their quality and suitability. With the aim of identifying and monitoring both the influence of PPCPs and the suitability of effluents to be reused, this study proposes the development of a composite indicator (CI) related to PPCP presence in WWTPs, through the common weight multi-criteria decision analysis (MCDA)-data envelopment analysis (DEA) model. Obtaining a CI for PPCPs is a novel approach in the published literature, showing a new perspective in PPCP management and their influence in wastewater treatment. Furthermore, this study proposes an improvement on MCDA-DEA model which maintains the initial hierarchy obtained for the units analyzed. The development of CI is based on information about the technological, environmental, social, and biological issues of WWTPs. Results show that 4 of the 33 WWTPs analysed had the best CI values, meaning that their effluents have lower environmental impact. The development of a CI related to PPCPs in WWTPs suggests that further steps are needed to manage the WWTP effluents. Hence, the need to implement preventive measures in WWTPs has been shown, even though the removal of PPCPs is not yet part of European law. This work highlights the importance of considering PPCPs as priority pollutants in wastewater management and reuse frameworks, to guarantee low environmental impact and adapt wastewater reuse based on a circular economy approach. HIGHLIGHTS: Emerging contaminants (PPCPs) are used as effluent quality indicators. A composite indicator for PPCPs performance has been developed through MCDA-DEA model. Indicator obtained allow decision makers implementing concrete actions to assess effluent quality. Results show the improvement capacity of the effluents quality through PPCPs removing.

A Novel, Highly Potent NADPH-Dependent Cytochrome P450 Reductase from Waste Liza klunzingeri Liver

The use of marine enzymes as catalysts for biotechnological applications is a topical subject. Marine enzymes usually display better operational properties than their animal, plant or bacterial counterparts, enlarging the range of possible biotechnological applications. Due to the fact that cytochrome P450 enzymes can degrade many different toxic environmental compounds, these enzymes have emerged as valuable tools in bioremediation processes. The present work describes the isolation, purification and biochemical characterization of a liver NADPH-dependent cytochrome P450 reductase (CPR) from the marine fish Liza klunzingeri (LkCPR). Experimental results revealed that LkCPR is a monomer of approximately 75 kDa that is active in a wide range of pH values (6-9) and temperatures (40-60 °C), showing the highest catalytic activity at pH 8 and 50 °C. The activation energy of the enzyme reaction was 16.3 kcal mol^-1 K^-1. The K_M values for cytochrome C and NADPH were 8.83 μM and 7.26 μM, and the k_cat values were 206.79 s^-1 and 202.93 s^-1, respectively. LkCPR displayed a specific activity versus cytochrome C of 402.07 µmol min^-1 mg¹, the highest activity value described for a CPR up to date (3.2-4.7 times higher than the most active reported CPRs) and showed the highest thermostability described for a CPR. Taking into account all these remarkable catalytic features, LkCPR offers great potential to be used as a suitable biocatalyst.

Enzyme Sensing Using 2-Mercaptopyridine-Carbonitrile Reporters and Surface-Enhanced Raman Scattering

The high sensitivity and functional group selectivity of surface-enhanced Raman scattering (SERS) make it an attractive method for enzyme sensing, but there is currently a severe lack of enzyme substrates that release SERS reporter molecules with favorable detection properties. We find that 2-mercaptopyridine-3-carbonitrile ( o-MPN) and 2-mercaptopyridine-5-carbonitrile ( p-MPN) are highly effective as SERS reporter molecules that can be captured by silver or gold nanoparticles to give intense SERS spectra, each with a distinctive nitrile peak at 2230 cm^-1. p-MPN is a more sensitive reporter and can be detected at low nanomolar concentrations. An assay validation study synthesized two novel substrate molecules, Glc-o-MPN and Glc-p-MPN, and showed that they can be cleaved efficiently by β-glucosidase (K _m = 228 and 162 μM, respectively), an enzyme with broad industrial and biomedical utility. Moreover, SERS detection of the released reporters ( o-MPN or p-MPN) enabled sensing of β-glucosidase activity and β-glucosidase inhibition. Comparative experiments using a crude almond flour extract showed that the presence of β-glucosidase activity could be confirmed by SERS detection in a much shorter time period (>10 time shorter) than by UV-vis absorption detection. It is likely that a wide range of enzyme assays and diagnostic tests can be developed using 2-mercaptopyridine-carbonitriles as SERS reporter molecules.

Humoral responses during wound healing in Holothuria tubulosa (Gmelin, 1788)

Wounds in living organisms trigger tissue-repair mechanisms. The sea cucumber (Holoturia tubulosa) is an excellent model species for achieving a better understanding of the humoral and cellular aspects involved in such healing processes. Consequently, this study assesses data on its morphometric, physiological and humoral responses 1, 2, 6, 24 and 48h after wound induction. In particular, morphometric data on the weight, width, length and coelomic-fluid volume of the species were estimated at different times during our experiments. In addition, the humoral aspects related to the enzymatic activity of esterase, alkaline phosphatase and peroxidase, as well as the cytotoxic activity of cell lysates (CL) and cell-free coelomic fluids (CfCf) are evaluated for the first time. Our results reveal a significant decrease in body length and weight, along with time-dependent, significant changes in the esterase, alkaline phosphatase, peroxidase and cytotoxic activity in both the CL and CfCf. The data obtained lead to the pioneering finding that there is an important time-dependent involvement of morphometric (changes in weight and length) and humoral (enzymatic and cytotoxic) responses in wound healing.

Underwater high frequency noise: Biological responses in sea urchin Arbacia lixula (Linnaeus, 1758)

Marine life is extremely sensitive to the effects of environmental noise due to its reliance on underwater sounds for basic life functions, such as searching for food and mating. However, the effects on invertebrate species are not yet fully understood. The aim of this study was to determine the biochemical responses of Arbacia lixula exposed to high-frequency noise. Protein concentration, enzyme activity (esterase, phosphatase and peroxidase) and cytotoxicity in coelomic fluid were compared in individuals exposed for three hours to consecutive linear sweeps of 100 to 200 kHz lasting 1 s, and control specimens. Sound pressure levels ranged between 145 and 160 dB re 1μPa. Coelomic fluid was extracted and the gene and protein expression of HSP70 with RT-PCR was evaluated on coelomocytes. A significant change was found in enzyme activity and in the expression of the HSP70 gene and protein compared to the control. These results suggested that high-frequency stimuli elicit a noise-induced physiological stress response in A. lixula, confirming the vulnerability of this species to acoustic exposure. Furthermore, these findings provide the first evidence that cell-free coelomic fluid can be used as a signal to evaluate noise exposure in marine invertebrates.