Bioaugmentation as a green technology for hydrocarbon pollution remediation. Problems and prospects.

Environmental pollution mitigation measure involving bioremediation technology is a sustainable intervention for a greener ecosystem biorecovery, especially the obnoxious hydrocarbons, xenobiotics, and other environmental pollutants induced by anthropogenic stressors. Several successful case studies have provided evidence to this paradigm including the putative adoption that the technology is eco-friendly, cost-effective, and shows a high tendency for total contaminants mineralization into innocuous bye-products. The present review reports advances in bioremediation, types, and strategies conventionally adopted in contaminant clean-up. It identified that natural attenuation and biostimulation are faced with notable limitations including the poor remedial outcome under the natural attenuation system and the residual contamination occasion following a biostimulation operation. It remarks that the use of genetically engineered microorganisms shows a potentially promising insight as a prudent remedial approach but is currently challenged by few ethical restrictions and the rural unavailability of the technology. It underscores that bioaugmentation, particularly the use of high cell density assemblages referred to as microbial consortia possess promising remedial prospects thus offers a more sustainable environmental security. The authors, therefore, recommend bioaugmentation for large scale contaminated sites in regions where environmental degradation is commonplace.

Dynamics of mitochondrial adaptation and energy metabolism in rainbow trout (Oncorhynchus mykiss) in response to sustainable diet and temperature.

Impacts of plant-based ingredients and temperatures on energy metabolism in rainbow trout was investigated. A total of 288 fish (mean body weight: 45.6 g) were fed four isocaloric, isolipidic, and isonitrogenous diets containing 40% protein and 20% lipid and formulated as 100% animal-based protein (AP) and a blend of 50% fish oil (FO) and 50% camelina oil (CO); 100% AP and100% CO; 100% plant-based protein (PP) and a blend of 50% FO and 50% CO or 100% PP and 100% CO at 14 or 18 °C for 150 d. Diet did not significantly affect weight gain (WG) (P = 0.1902), condition factor (CF) (P = 0.0833) or specific growth rate (SGR) (P = 0.1511), but diet significantly impacted both feed efficiency (FE) (P = 0.0076) and feed intake (FI) (P = 0.0076). Temperature did not significantly affect WG (P = 0.1231), FE (P = 0.0634), FI (P = 0.0879), CF (P = 0.8277), or SGR (P = 0.1232). The diet × temperature interaction did not significantly affect WG (P = 0.7203), FE (P = 0.4799), FI (P = 0.2783), CF (P = 0.5071), or SGR (P = 0.7429). Furthermore, temperature did not influence protein efficiency ratio (P = 0.0633), lipid efficiency ratio (P = 0.0630), protein productive value (P = 0.0756), energy productive value (P = 0.1048), and lipid productive value (P = 0.1386); however, diet had significant main effects on PER (P = 0.0076), LPV (P = 0.0075), and PPV (P = 0.0138). Temperature regimens induced increased activities of mitochondrial complexes I (P = 0.0120), II (P = 0.0008), III (P = 0.0010), IV (P < 0.0001), V (P < 0.0001), and citrate synthase (CS) (P < 0.0001) in the intestine; complexes I (P < 0.0001), II (P < 0.0001), and CS (P = 0.0122) in the muscle; and complexes I (P < 0.0001), II (P < 0.0001), and III (P < 0.0001) in the liver. Similarly, dietary composition significantly affected complexes I (P < 0.0001), II (P < 0.0001), IV (P < 0.0001), V (P < 0.0001), and CS (P < 0.0001) in the intestine; complexes I (P < 0.0001), II (P < 0.0001), III (P = 0.0002), IV (P < 0.0001), V (P = 0.0060), and CS (P < 0.0001) in the muscle; and complexes I (P < 0.0001), II (P < 0.0001), IV (P < 0.0001), V (P < 0.0001), and CS (P < 0.0001) in the liver activities except complex III activities in intestine (P = 0.0817) and liver (P = 0.4662). The diet × temperature interaction impacted CS activity in the intestine (P = 0.0010), complex II in the muscle (P = 0.0079), and complexes I (P = 0.0009) and II (P = 0.0348) in the liver. Overall, comparing partial to full dietary substitution of FO with CO, partial dietary replacement showed similar effects on complex activities.

Diets are one of the most important consideration in aquaculture production as more than 50% of production costs are incurred in raising cultured fish to market size. As the price of FM and FO continues to increase, it is necessary to seek alternative sources of proteins and oils for sustainable aquaculture development. Plant-based ingredient sources have appeared as sustainable alternatives; however, it is uncertain whether the uses of plant-based alternatives will be appropriate in securing the production of carnivorous aquaculture species in the context of global warming, with studies postulating on the potential effects of climate change on fish growth and health. A study was conducted to examine how the replacement of FM and FO with sustainable plant-based protein and camelina oil (CO) as ingredient sources at 14 or 18 °C would affect the growth performance, nutrient utilization efficiencies, and mitochondrial enzyme activity in rainbow trout. Based on the results, mitochondrial enzyme activities were generally higher at 18 °C and CO could replace 50% dietary FO without negative effects on rainbow trout. Overall, our study demonstrated that animal-based protein with CO is as good as animal-based with FO for growth and health, thus providing potentially sustainable diet options for aquaculture.