AQUATIC PHYSIOLOGY AND BIOTECHNOLOGY
Year:2020 | Volume:8 | Issue:1|Papers Count:8

This study aimed to investigate the phenotypic and genotypic patterns of antibiotic resistance in two potential probiotic lactic acid bacteria, Lactococcus lactis subsp. cremoris (NABRII64 and NABRII66) isolated from the rainbow trout intestine. The phenotypic susceptibility pattern of the strains was studied based on the Minimum Inhibitory Concentration (MIC) of eight most commonly used antibiotics in medicine and veterinary including ampicillin, kanamycin, gentamicin, streptomycin, erythromycin, clindamycin, tetracycline and chloramphenicol. After comparing the MICs with standard values recommended by European Food Safety Authority (EFSA), the nature of the phenotypic resistance observed in bacterial strains was investigated by polymerase chain reaction (PCR) through plasmid DNA extraction. The results of phenotypic evaluation indicated the tetracycline resistance in both bacterial strains (MIC<4mg/L). Genotyping of antibiotic resistance genes including tet (S), tet (L), tet (M), tet (O), tet (W) and tet (K) indicated the presence of tet (S) and tet (M) resistance genes in plasmid DNA of both bacterial strains. These results exhibited the acquired resistance and the presence of two tetracycline resistance genes in the plasmid DNA of two bacterial strains, NABRII64 and NABRII66. However, further studies are required to understand the nature of the acquired resistance mechanism in the future.

Water samples were collected from Gheynarjeh hot water spring, around Sabalan Mountain in Ardebil province. One isolate (Gh1), isolated from the hot water spring was chosen for further studies. This selection was based on the isolates ability to grow faster and within the temperature limits chosen. Isolate characteristics were determined by culture on various selective aerobic and anaerobic media, biochemical assays, identification of typical lipids, 16S rDNA sequencing and drawing the phylogenetic tree. Isolate Gh1 was 1μ m wide and 3-4μ m in length and an endosporeforming non-motile Gram positive bacillus with rectangular terminal spores. The optimal growth temperature was 58-60° C, with Tmin and Tmax at 30° C and 72° C, respectively. The optimal pH for growth was 8. 0 and it grew between pH 6 and 10. NaCl concentrations of 0. 5– 1. 0% encouraged growth, but at 2% NaCl, growth was inhibited. The only carbohydrate source with a positive effect on bacterial growth was starch. The isolate exhibited amylolytic as well as gelatinolytic, catalase and oxidase activities. The isolate was aerobic and no growth was observed on anaerobic medium. Cell wall fatty acid analysis showed the presence of phosphatidyl ethanolamine, diphosphatidyl glycerol, phosphatidyl glycerol and several unidentified lipids and phospholipids. Diaminopimelic acid could not be detected in the peptidoglycan. The 16S rDNA sequence analysis exhibited 99. 72% identity with Aeribacillus pallidus. Other important characteristics, such as movement and anaerobiosis were different from those previously reported isolates. In addition, the results showed that the presence/absence of phosphatidyl ethanolamine cannot be used as a variable for differentiating between Geobacillus and Aeribacillus.

This study was aimed to investigate the effects of different concentrations of Lactobacillus casei on some serum biochemicals and antioxidant factors in rainbow trout exposed to foodborne lead toxicity. For this purpose, 375 juvenile fish (15± 4. 6g) were randomly divided into five groups in three replications. Group 1, 2 and 3 were respectively fed with a diet containing 5×10 6, 5×10 7 and 5×10 8 CFU/g Lactobacillus casei throughout the experiment. Group 4 (negative control) was fed with a basal diet (no probiotic and lead) during all experiment period. Group 5 (positive control) was fed with the basal diet for 45 days and was subsequently fed with diets containing 500 µ g/kg lead nitrate similar to the probiotic groups for 21 days. Blood sampling was performed to measure the parameters on days of 0, 45, 52, 59 and 66. The results showed that LDH, cholesterol and triglyceride levels were significantly reduced in most probiotic treatments after probiotic consumption for 45 days compared to a negative control group (P<0. 05). After exposure to lead, serum ALP and LDH values in group 2 were significantly lower than group 5 (P<0. 05). In group 2, GSH enzyme levels significantly increased compared to group 5 on day 52 (P<0. 05). The findings of this study showed that supplementing diet with Lactobacillus casei in rainbow trout can be effective in preventing the chronic effects of lead poisoning by improving the biochemical and antioxidant indices. It seems that level of 5×10 7 CFU/g of probiotic bacteria had an ameliorative effect on improving the biomarkers.

Industrial usage of different macroalgae has grown exponentially during the last decade. Nutritional applications for human feeding and multiple therapeutic are their main important exploitation. This study aimed to investigate the biological activities of the organic, water and ethyl acetate fractions of two brown algae Polycladia myrica and Padina sp., collected from the coast of Qeshm Island. In this experimental study, for identification of the superior species, the tested biological activities included antioxidant assay at gradient concentrations by ferric reducing power assay, FRAP, inhibition free radicals DPPH and ABTS, total phenolic and phlorotannins content, and antibacterial assay by disk diffusion. The more effective algal fractions by maximum antioxidant capacity in all tested methods were recorded for ethyl acetate fractions in both macroalgae. Only ethyl acetate fraction of Padina sp. had an antibacterial effect on all studied strains. Both brown algae, Polycladia myrica and Padina sp., had antioxidant and antibacterial activities, but Padina sp. due to the high amount of phenol and phlorotannins and high antioxidant and antibacterial power can be introduced as a priority species for biological properties.

This study was performed to improve the physiological responses of rainbow trout to chronic stress of ammonia, as an inhibiting factor in recirculating aquaculture system, by using dietary antioxidant. 150 fish (initial mean weight of 8. 4± 0. 84 g) were investigated in five treatments, each with three replicates for 60 days including fish fed with no supplemented food without ammonia exposure (C-), without supplemented food but with ammonia exposure (C + ), with supplementation of vitamin E and ammonia exposure, with supplementation of nano-selenium and ammonia exposure (Se) and with supplementation of combined vitamin E and nanoselenium with ammonia exposure (E+Se). After 30 days of feeding with supplements, the fish were exposed to the ammonia (NH4OH: 0. 2 ppm) for 30 days. Growth and hematological parameters were studied at days of 44 and 60. Results showed that feeding fishes with E+Se increased the growth parameters and reduced plasma ammonia compared to other treatments. Fish fed with E+Se had the highest RBC, hemoglobin and hematocrit levels while WBC was not significant compared to C- group. These results indicated the synergistic effects of dietary E+Se supplement in rainbow trout fish, it could compensate the imposed damaged by ammonia pollutions.

In this study the effect of streptococosis/lactococosis bacterin administrated via oral, bath and intraperitoneal routes on the expression of two immune related genes (IgM and IL-6) was investigated. 600 fish (14± 2. 1g) were randomly divided into 4 groups in triplicates. Group 1 was vaccinated via oral route using 10 8 CFU bacterial cell (Streptococcus iniae and Lactococcus garvieae) in each gram of food. Group 2 was injected with 0. 1mL of 10 9 CFU/mL bacterin. Group 3 was vaccinated via immersion route for 2 minutes in 10 9 CFU/mL. Group 4 was none immunized group without vaccination. Fish were reared for two months in a similar situation. At days of 0, 20, 40 and 60, antibody titer against both bacteria was performed by ELISA method and expression of IL-6 and IgM genes were evaluated through qRT-PCR method. Then fishes were exposed to S. iniae and L. garvieae separately at the end of the experiment and the rate of mortality was compared among the groups. The results showed that the rate of mortality in exposed fish to S. iniae in injection, oral, immersion and unvaccinated routs were 20± 10, 56. 3± 10, 50± 5. 67 and 90± 3. 67 whereas in exposed fish to L. garvieae were 26. 67± 5. 77, 57. 7± 10, 43. 33± 5. 67 and 90± 4. 63 respectively. The antibody titer in the vaccine injection group was increased compared to the control (P<0. 05). Expression of IL-6 and IgM in vaccinated groups was significantly increased compared to control group (P<0. 05) with the highest rate in the injection group. It can be concluded that although injection route causes the best protection, antibody titer and expression of immune genes, oral and immersion routes could also induce relative protection and immunogenicity in rainbow trout and each route possesses some priority over other routes then further research on efficacy improvement of each route can be recommended.

In the present study, the effects of magnetized water on total protein, albumin, red blood cells (RBC), white blood cells (WBC), hemoglobin and hematocrit level in sterlet (Acipenser ruthenus) were examined. Fish (40 individuals, 100. 46± 4. 51g, 31. 73± 0. 80cm) were exposed to magnetized water with different intensities (5, 15, 25 mT), with a control group. Each treatment consisted of two repeats and each repeat contained 5 individuals. A sampling of exposed and control fishes were done at 30 and 60 days. Based on the results, there were not any significant differences between the control group and treated fishes with different intensities in red and white blood cells, hematocrit, and hemoglobin after 30 and 60 days (P>0. 05). Also, there were not any significant differences between the control group and treated fishes with different intensities in total protein and albumin levels after 30 and 60 days (P>0. 05). This study is the first research about the effects of magnetized water on Acipenser ruthenus in a relatively long period that could be future studies basis.

Today, due to the high consumption of biodegradable resistant polymers, there is a huge problem of the accumulation of polymer waste in nature. Polyhydroxyalkonoates are biodegradable compounds that are very much considered for replacement with synthetic plastics. In this study, the effects of salt concentration changes on the production of polyhydroxybutyrate by cyanobacteria Spirulina sp. were investigated. Spirulina was cultured in Zarrouk medium containing half (1/2X), equal (X, as control), double (2X) and triple (3X) salt concentrations for 20 days. Quality and quantity of polyhydroxybutyrate were analyzed by measuring growth, protein content and lipid peroxidation. The growth rate of Spirulina sp. in the medium containing increased and decreased concentrations of salts did not change significantly. However, lipid peroxidation and protein increased and decreased, respectively, by increasing salt concentration to 3 times as compared to control. The amount of polyhydroxybutyrate under salt concentrations of 1/2X, X, 2X and 3X were 0. 011, 0. 014, 0. 019 and 0. 006 (g/g dcw) respectively. As a result, treatment with 2X salt concentration is more suitable for polyhydroxybutyrate producing than other treatments.