فصلنامه فیزیولوژی و بیوتکنولوژی آبزیان
سال یازدهم شماره 1 (بهار 1402)

The purpose of this study was to evaluate the potential of deep aquifer well water located in Sistan region (southeastern of Iran) for growing Dunaliella tertiolecta. For this purpose, 5 treatments including deep aquifer well water with salinities of 20 and 35ppt, deep aquifer well water and salt of Urmia Lake (35 ppt) and tap water with salinities of 20 and 35ppt were considered and  D. tertiolecta microalgae was reared for 24 days under standard conditions (temperature 26±1ºC, light 2000 lux, 16 hours light and 8 hours darkness). The results showed that the pH value in all treatments increased slightly until day 6 but then decreased and had a steady trend from day 12 to 24. The highest amount of growth, chlorophyll a and carotenoid production, specific growth rate, the least doubling time and the highest rate of division were observed in deep aquifer well water treatment (salinity 20 ppt), although the lowest amount of biomass production was in this treatment. Based on these results, it can be said that if salt is added to deep aquifer well water, by changing the composition and increasing salinity, the amount of biomass produced will increase. In general, D. tertiolecta can be grown in deep aquifer well water (No. 1) extracted in Sistan region

Monitoring of the pollutant effects in the biological environment requires the identification of a suitable biomarker. In this study, the efficacy of the expression of the CYP1 gene and the antioxidant enzymes in the Scatophagus argus were studied as biomarker of oil pollutants at three stations (Bandargah, Solhabad and Jofreh) and the control samples. CYP1A gene expression in liver was significantly different from control samples in all regions. The highest CYP1 gene expression was measured in Solhabad station. CYP1A gene expression in the gills of green scat fish showed a significant increase compared to control samples. The highest and lowest CYP1A gene expression was observed in the gills in Solhabad and Bandargah samples, respectively. The amount of superoxide dismutase and catalase of liver tissue in Jofrah and Solhabad stations were significantly lower than the control (P<0.05). In contrast, the rate of lipid peroxidation and GST were directly correlated with the amount of polycyclic aromatic hydrocarbons (P<0.05, R=0.96). Due to the relationship between CYP1A gene expression and antioxidant markers and the level of contamination, CYP1A gene expression and antioxidant markers can be used as a suitable biomarker for PAH contaminants in this species.

Microbial proteases have a large portion of the market of industrial enzymes, because of their wide application in detergents, drug enzymes and animal feed processing. Bacillus strains potentially produce a significant quantity of proteases, due to their physiological properties. In this study, first, the gene encoding carboxypeptidase from Bacillus persicus was isolated by PCR and using primers with NdeI and XhoI restriction sites. After digestion of the PCR product, it was cloned into the appropriate site at PET28a+ vector, then recombinant plasmids transformed into E. coli BL21)DE3( strain. Plasmids with positive colony PCR result were sent for sequencing for final confirmation, then, recombinant enzyme expression was optimized at different temperature and time conditions, then purified with nickel embedded agarose affinity chromatography.  IPTG concentration of 0.4mM at 32°C and incubation time of 20 hours provided the maximum amount of enzyme expression. Molecular weight of the carboxypeptidase was estimated approximately 58KDa. Considering the high amount of expression of the soluble protein and the easy optimization of its expression and purification in laboratory conditions, if the enzyme activity in the presence of standard substrates is adequate, and also if additional studies show the possibility of optimal and cost-effective production of a high amount of this enzyme in a large volume and pilot conditions, it can be hoped that this enzyme is a suitable option for industrial purposes.

In this study, the effect of dietary butyrate monoglyceride and probiotic (Bacillus subtilis and Bacillus licheniformis) supplementation were evaluated on growth performance and the enzymatic antioxidant activity of Nile tilapia (Oreochromis niloticus). Fish were divided into 4 treatments with 3 replications including control, 10g/kg butyrate monoglyceride (AB1), 5g/kg probiotic Bacillus (AB2), 10g/kg butyrate monoglyceride and 5g/kg probiotic Bacillus (AB3). 144 fish with an average weight of 12±0.58g were fed for 8 weeks. This study showed that applying butyrate monoglyceride and probiotic Bacillus in the feeding of Nile tilapia significantly improved the growth indices of final weight gain (FWG), daily weight gain (DWG), protein efficiency ratio (PER), and FCR compared to control (P<0.05). All experimental diets had higher levels of catalase, glutathione peroxidase and superoxide dismutase activity compared to control (P<0.05). However, the highest levels of superoxide dismutase activity were measured in treatment AB3. The present study indicated that singular and combined dietary administration of butyrate monoglyceride and probiotic Bacillus had a significant impact on growth performance, and liver and serum enzymatic antioxidant activity of Nile tilapia.