Olive oil mill wastewater toxicity in the marine environment: alterations of stress indices in tissues of mussel Mytilus galloprovincialis

This study investigated the impact of olive mill wastewater (OMW) as a pollutant of the marine environment, via the detection of stress indice alterations in mussels Mytilus galloprovincialis. Due to the absence of data concerning the levels of OMW in the receiving waters, mortality test (96 h) was first performed in order to estimate the range of OMW concentration where no mortality occurs. OMW concentrations ranging from 0.01 to 0.1% (v/v) showed no increased mortality and thus were used for the determination of pre-pathological alterations in tissues of mussels. In particular, mussels exposed to either 0.1 or 0.01% (v/v) OMW for 5 days showed significant alterations of stress indices in their tissues. Specifically, decreased neutral red retention (NRR) assay time values, inhibition of acetylcholinesterase (AChE) activity, as well as a significant increase of micronucleus (MN) frequency and DNA damage were detected in haemolymph/haemocytes and gills, compared with values measured in tissues of control mussels. The results of the present study showed that OMW disposal into the marine environment could induce pre-pathological alterations in marine organisms, before severe disturbances, such as disease, mortality, or population changes occur.     

Feed supplemented with polyphenolic byproduct from olive mill wastewater processing improves the redox status in blood and tissues of piglets

In the present study, a polyphenolic byproduct from olive mill wastewater (OMWW) was used for making piglet feed with antioxidant activity. For examining the antioxidant capacity of the feed, 30 piglets of 20 d old were divided into two groups receiving basal or experimental feed for 30 d. Blood and tissue samples were drawn at days 2, 20, 35 and 50 post-birth. The tissues collected were brain, heart, kidney, liver, lung, quadriceps muscle, pancreas, spleen and stomach. The antioxidant effects of the experimental feed were assessed by measuring oxidative stress biomarkers in blood and tissues. The oxidative stress markers were total antioxidant capacity (TAC), glutathione (GSH), catalase activity (CAT), protein carbonyls (CARB) and thiobarbituric acid reactive species (TBARS). The results showed that piglets fed with diet supplemented with OMWW polyphenols had significantly increased antioxidant mechanisms in blood and the majority of the tested tissues as shown by increases in TAC, CAT and GSH compared to control group. Moreover, piglets fed with the experimental feed exhibited decreased oxidative stress-induced damage to lipids and proteins as shown by decreases in TBARS and CARB respectively. This is the first study in which OMWW polyphenols were used for making pig feed with antioxidant activity.