Biomonitoring of aquatic environments requires new tools to characterize the effects of pollutants on living organisms. Zebra mussels (Dreissena polymorpha) from the same site in north-eastern France were caged for two months, upstream and downstream of three wastewater treatment plants (WWTPs) in the international watershed of the Meuse (Charleville-Mézières “CM” in France, Namur “Nam” and Charleroi “Cr” in Belgium). The aim was to test ¹H-NMR metabolomics for the assessment of water bodies’ quality. The metabolomic approach was combined with a more “classical” one, i.e., the measurement of a range of energy biomarkers: lactate dehydrogenase (LDH), lipase, acid phosphatase (ACP) and amylase activities, condition index (CI), total reserves, electron transport system (ETS) activity and cellular energy allocation (CEA). Five of the eight energy biomarkers were significantly impacted (LDH, ACP, lipase, total reserves and ETS), without a clear pattern between sites (Up and Down) and stations (CM, Nam and Cr). The metabolomic approach revealed variations among the three stations, and also between the upstream and downstream of Nam and CM WWTPs. A total of 28 known metabolites was detected, among which four (lactate, glycine, maltose and glutamate) explained the observed metabolome variations between sites and stations, in accordance with chemical exposure levels. Metabolome changes suggest that zebra mussel exposure to field contamination could alter their osmoregulation and anaerobic metabolism capacities. This study reveals that lactate is a potential biomarker of interest, and ¹H-NMR metabolomics can be an efficient approach to assess the health status of zebra mussels in the biomonitoring of aquatic environments.

Heavy metals have been found in increasing concentrations in the aquatic environment. Fishes exposed to such metals have altered gene expression, serum profiles, tissue histology and bioindices that serve as overall health biomarkers. The heavy metals (Ni, Cd, and Cr) accumulated in water and fish tissues, were beyond the permissible limits defined by the Central Pollution Control Board/World Health Organization. Metallothionein (MT) and glutathione peroxidase (GPX) genes expression patterns highlighted the metal-specific exposure of fish. An increased fold change of genes against beta-actin serves as a potential feature for toxicity. Metal toxicity is also reflected by an increased level of digestive enzymes (amylase and lipase) in the serum and alterations in values of reproductive hormones (11-Ketotestosterone and progesterone). Total serum bilirubin attribute to the liver and biliary tract disease in fishes. Histopathological studies show cellular degeneration, breakage, vacuolization signifying the chronic stress.

The aim of the present study was to verify the antimicrobial susceptibility profile and virulence factors of Vibrio parahaemolyticus isolated from water and bivalve mollusks. A high percentage of V. parahaemolyticus was isolated in natura, processed bivalves tissues, and surrounding water (75%, 20%, and 59%, respectively). The most potential virulence phenotype in V. parahaemolyticus isolates was amylase production (97%) followed by DNase (83%), phospholipase (70%), β-hemolytic activity (57%). The tdh and trh genes were not detected. Besides, a high antimicrobial resistance was observed for ampicillin (97%), minimum inhibitory concentration [MIC] = 400 μg and cephalothin (93%, MIC ≤ 100 μg). The absence of expression of tdh and trh virulence genes excluded the toxigenic potential of V. parahaemolyticus isolates; however, the high prevalence of antimicrobial resistance among the environmental strains is a risk to human health.

The information about toxic effects of thiamethoxam on non-target aquatic organisms is still incomplete. The semi-static toxicity test method was used to investigate the acute toxic effects of thiamethoxam on Eriocheir sinensis. The results showed that the median lethal concentration (LC50) of thiamethoxam to E. sinensis at 96 h was 510 μg/L, and the safety concentration (SC) was 51 μg/L. After 96 h exposure to thiamethoxam, the survival rates of crabs at concentrations of 0, 151.11, 226.67, 340, and 510 μg/L were 100%, 76.19%, 64.29%, 61.91%, and 46.43%, respectively. A significant (P < 0.05) decrease of the number of hemocytes was observed in thiamethoxam groups. With the increase of thiamethoxam concentration, the phagocytic activity of hemocytes, the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), total antioxidant capacity (T-AOC), and the activities of protease, amylase, and lipase of crabs increased firstly and then decreased, and the above indexes reached the maximum in 151.11 μg/L thiamethoxam group. Collectively, a high concentration of thiamethoxam (510 μg/L) had a great effect on the gene expression of immune metabolism-related factors in hepatopancreas and gill of crabs. These findings indicated that thiamethoxam exposure had the ability to impair immune and metabolic systems and resulted in the reduction of survival rate of crabs.

Lead is a metal capable of affecting physiology and metabolism in fish, including Nile tilapia (Oreochromis niloticus). However, few studies have evaluated the effects of lead on digestive enzyme activities in fry. At that stage, independent feeding begins, and there is increased demand and consumption of food, so chronic exposure to metal during this stage of development would cause null or minimal growth in organisms. In this study, fry from Nile tilapia was used to evaluate the effects of lead acetate by chronic exposure on the growth and the activities of the digestive enzymes after 30 and 60 days exposures. Four treatment groups 0.025, 0.050, 0.075 and 0.100 mg/L of lead acetate and a lead-free control were established. The activity of enzymes decreased, in the case of acidic proteases after 30 days and lipases after 60 days of exposure, from 0.025 and 0.050 mg/L of lead acetate, respectively. The amylase activity increased in metal-treated, while the chymotrypsin decreased partially at 60 days. Lipases decreasing activity might be causing an increase of triglycerides (lipids) and body mass observed during the first 30 days of exposure. Concentrations, equal to or above 0.075 mg Pb/L, cause significant effects on size and weight of fry, with nearly 54% lower than controls. At chronic exposure and early stage of development, the enzymatic activity is partially reduced along with body weight gain, which would affect subsequent growing and aquaculture production. The digestive enzyme response is discussed as a possible limited biomarker of exposure, to be used in biomonitoring.

A bioenhancement strategy for improving the anaerobic degradation efficiency of ship domestic sewage under microaerobic conditions was proposed in this study. Strains Stenotrophomonas sp. MSPP05 and Prevotella sp. MSPP07 with high organic-degrading efficiency and extracellular hydrolase yield were used for the bioenhancement of activated sludge. In batch experiments, the removal rates of chemical oxygen demand and total nitrogen reached 94.5% and 66.9% after 72 h of degradation. The activities of dehydrogenase, extracellular amylase, and protease in the treatment group were 1.2, 1.4, and 2.0 times higher than those in the control group. Microbial community analysis showed that exogenous enhanced strains competed with original microorganisms and became dominant. One-stage continuous stirred tank reactor with bioenhanced activated sludge ran steadily for 90 days with average effluent COD and TN concentrations of 87.5 and 14.6 mg/L. The feasibility of improving organic-degrading efficiency through bioenhancement by using exogenous hydrolase-producing strains was confirmed under microaerobic conditions. This work provided a theoretical basis for improving treatment effects and developing a new technique for ship domestic sewage treatment.

High toxicity of dimethoate requires efficient ways for detoxification and removal of its residues in contaminated environments. Microbial remediation is a process that utilizes the degradation potential of microbes to provide a cost-effective and reliable approach for pesticide abatement. For this purpose, a dimethoate-degrading bacterium Brucella sp. was isolated from a contaminated agricultural soil sample in Multan, Pakistan. This isolate was found to tolerate up to 100 ppm of dimethoate in minimal salt medium and was further evaluated for plant growth-promoting traits. The strain gave positive results for amylase, ammonia, and catalase production, while other traits such as indole acetic acid production and potassium solubilization were also confirmed. Thus, the strain could play an important role for plant nutrient transmission in the plant rhizosphere. Optimization of growth parameters (i.e., pH and temperature) depicted the potential of PS4 to be best tolerating dimethoate, with maximum cell density at λ 600 nm. Optimum pH and temperature for growth were found to be 6 and 35 °C, respectively. Based on optimization results as well as different attributes, the rhizospheric bacterial isolate PS4 was further subjected to a batch degradation experiment under different concentrations of dimethoate (25, 50, 75, and 100 ppm). This promising dimethoate-degrading isolate was found to degrade 83% of dimethoate (at 100 ppm) within a period of 7 days. In addition, it degraded 88% of dimethoate at 50 ppm, indicating that the bacterial isolate utilized dimethoate solely as a source of energy. The strain followed the first order reaction kinetics, depicting its dependence on dimethoate as energy and carbon source. Molecular profiling further supported its role in plant growth promotion and multi-stress tolerance. This research showed that Brucella sp. is capable of degrading dimethoate, and therefore, it would be useful in the investigation of novel bioremediation techniques at pesticide-polluted sites.

The phytoremediation potential and enzymatic defense of a medicinal herb Leucas aspera was studied in the crude oil contaminated soil. The productivity, antioxidants, and phytochemical and functional group profiles of the plant species in stress conditions were investigated. Besides, changes in enzymes, beneficial bacterial population, and physico-chemical and total oil and grease (TOG) profiles in the contaminated soil were also studied. The results showed improvement in physico-chemical conditions, increase in beneficial bacterial population (4.1–5.4 folds), and decrease in TOG (31.3%) level of the contaminated soil by end of the experimental trials. The L. aspera treated contaminated soil showed enhancement in dehydrogenase (32.3%), urease (102.8%), alkaline phosphatase (174.4%), catalase (68.5%), amylase (76.16%), and cellulase (23.6%) activities by end of the experimental trials. Furthermore, there were significant variations in leaf area index, chlorophyll, and biomass contents of the experimental plant as against the initial level and control. Besides, the significant reduction in IC₅₀ values (24–27.4%) of L. aspera samples grown in contaminated soil confirms the strong antioxidant enzymatic defense of the plant species against the crude oil associated abiotic stress. The Fourier-transform infrared (FT-IR) analysis confirmed the uptake and metabolism of aliphatic hydrocarbons, aldehydes, alkyl halides, and nitro compounds by the experimental plant from the contaminated soil.

High costs of conventional protein feed sources including soybean meal (SBM) generated the need for finding other alternatives. Thus, the present study was designed to evaluate the impact of graded replacements of SBM by sunflower seed meal (SFM) with or without enzyme supplementation on growth performance, digestive enzymes, carcass traits, and blood profile of broiler chickens. A total of 240 unsexed 1-week-old broiler chicks (Hubbard) were randomly divided into eight treatment groups of 30 chicks each in five replicates each of six chicks in a factorial design (4 × 2) arrangement, including four levels of SFM (0, 25, 50, and 75% replacing SBM) and two levels of enzyme (0- or 0.1-g/kg diet) supplementation. Performance traits including feed conversion ratio, body weight, and weight gain were significantly (P < 0.01) improved with increasing SFM up to 50% substitution for SBM or with enzyme supplementation in broiler diet during the experiment. However, feed intake of broiler chicks was decreased with enzyme supplementation (P < 0.05). The activities of digestive enzymes (protease and amylase) were significantly (P < 0.05) influenced and enhanced by SFM and enzyme inclusion in diets, respectively. The activities of protease and amylase were improved with SFM diet supplemented with 0.1 g/kg enzyme in comparison with those with the un-supplemented diet. The evaluated carcass traits were not statistically (P > 0.05) influenced by feeding SFM meal or enzyme addition. Biochemical blood parameters were significantly (P < 0.01) affected by SFM, enzyme, or their interaction in broiler diets, except for globulin that was not affected by dietary enzyme. It is concluded that increasing SFM level in the diet up to 50% replacing SBM with the supplementation of enzyme improved the growth performance and enhanced positively carcass traits as well as the activity of digestive enzymes in broiler chickens.