Investigation on Indigenous Bacillus Isolates With Bioremediation Properties for Improving Water Quality and Shrimp Health in Malaysian Aquaculture

Indigenous marine bacteria of the genus Bacillus were selected to study their properties as potential use for bioremediation owing to their inherent versatility. Bacteria were isolated from water and sediment samples collected along the west coast of Peninsular Malaysia in brackishwater environment. Selected isolates were identified to species level using biochemical and API CH kit and three suitable isolates, Bacillus pumilus AB58, B. subtilis AB65 and B. lichenifonnis AB69 were selected for the study. Optimum growth requirements of temperature, NaCI and pH were 30°C, 1.5% and 7.5 respectively, determined for the isolates by measuring the optical density and corresponding cell number. The growth curves of the isolates were plotted and all of them reached maximum cell number during a 16-20 h incubation. The cell density in overnight cultures of B. pumilus AB58, B. subtilis AB65 and B. licheniformis AB69 were 5.7xl09 (± 0.8), 3.7xl08 (± 0.6), 5.0x109 (± 0.6) cfu/ml respectively. They had the ability to tolerate ammonia levels of up to 20 mg/l without a considerable change in cell numbers for 48 h. However, the growth was suppressed completely at 25 mg/l of ammonia. At 40 ppt salinity, all the isolates survived for 4 days without significant change in initial cell numbers (108 cfu/ml). The selected isolates were found to secrete extracellular enzymes viz., protease, gelatinase, amylase and lipase as detected by clear zone formation on substrate based agar plates. Bacillus pumilus AB58 and B. subtilis AB65 produced significantly (P < 0.05) bigger protease clear zones (19.0 ± 2.0 and 23.0 ± 4.0 diameter in mm respectively) than B. licheniformis AB69. However, B. subtiUs AB65 secreted significantly (P < 0.05) more amylase (31.0 ± 5.0 diameter in mm) than the other two isolates. All the isolates were sensitive to most of the antibiotics tested on MHA plates. These isolates were compatible with each other in mixed culture conditions. They inhibited as well as excluded all the pathogenic vibrios (Vibrio algillolyticus MIl, V. alginolyticus M12, V. parahaemolyticus MI, V. parahaemolyticus M3, V. parahaemolyticus M6, V. alginolyticus T, V. parahaemolyticus T, V. harveyi I and V. parahaemolyticus I) tested by diffusion disc, streak plate and common broth methods. Synergistic effect of isolates had significantly higher (P < 0.05) inhibition of all vibrios than the individual isolates. The isolates were confirmed for their non-pathogenicity to shrimp postlarvae (PL 29). All three isolates were tested for their effect on ammonia in simulated pond conditions. All non-aerated treatment tanks had significantly lower ammonia levels (P < 0.05) than the non-aerated control tanks, which were not treated with bacterial isolates both in case of single and combination treatments. Synergistic effect of isolates reduced the ammonia levels at a faster rate than the treatments with single isolate. Sediment properties were not significantly different between treated and control groups except for the total and available phosphorous levels, which were significantly higher in tanks treated with B. licheniformis AB69 (P < 0.05) compared to the others. The selected Bacillus isolates satisfied the criteria to qualifY them for bioremediation in aquaculture

Comparison of four antibiotics with indigenous marine Bacillus spp. in controlling pathogenic bacteria from shrimp and Artemia

Use of antibiotics for the control of bacterial diseases in shrimp culture has caused several adverse impacts to the industry. This has resulted in the search for alternative environment friendly approaches to overcome bacterial infections. This study was conducted to investigate the use of beneficial bacteria as an alternative to antibiotics. Ten pathogenic bacterial species isolated from shrimp, Penaeus monodon, and Artemia cysts were tested for susceptibility to indigenous marine Bacillus subtilis AB65, Bacillus pumilus AB58,Bacillus licheniformis AB69 and compared with oxytetracycline, chloramphenicol, gentamicin and bacitracin, which are common antibiotics used in Asian aquaculture. The Bacillus spp. were isolated from the local marine environment for bioremediation use in shrimp hatcheries and were proven to reduce total ammonium nitrogen. The pathogenic bacterial isolates were 90% susceptible to B. subtilis AB65, 70% susceptible to B. pumilus AB58 and B. licheniformis AB69 and 100% susceptible to oxytetracycline, chloramphenicol and gentamicin but only 40% to bacitracin. Two representative isolates of the vibrio group, Vibrio alginolyticus VaM11 and Vibrio parahaemolyticus VpM1, when tested for competitive exclusion by a common broth method using the marine Bacillus spp., showed decreased viable counts from 108 to 102 cfu mL)1.The results suggest that the action of the marine bacteria appears to be significant in protecting the host shrimp against pathogenic bacteria. In addition to the alternative use of antibiotics, the selected marine bacteria had additional bioremediation properties of reducing ammonia

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Prompt neutron emission in the spontaneous fission of

An experiment on the study of the $$^{246}$$Fm spontaneous fission was conducted using the SHELS separator. The isotope was synthesized in the complete fusion reaction of $$^{40}$$Ar beam ions and $$^{208}$$Pb target nuclei. The neutron yields of $$^{246}$$Fm spontaneous fission ($${\overline{\nu }} = 3.79\pm 0.30$$, $$\sigma ^{2}_{\nu } = 2.1$$) were obtained using the SFiNx detector system. The multiplicity distribution of emitted prompt neutrons was restored using the Tikhonov method of statistical regularisation ($${\overline{\nu }}_{r} = 3.79\pm 0.20$$, $$\sigma ^{2}_{\nu r} = 2.8$$). The spontaneous fission branching ratio ($$b_{SF} = 0.061\pm 0.005$$) and the half-life ($$T_{1/2} = 1.50^{+0.08}_{-0.07}$$ s) of the isotope were determined. The experimental data were compared with scission point model predictions. An agreement was observed in the average number of neutrons per spontaneous fission process. However, the forms of the experimental and model prompt neutron multiplicity distributions differ significantly

Demographic and clinical profiles of Plasmodium falciparum and Plasmodium vivax patients at a tertiary care centre in southwestern India

Background: Malaria remains an important cause of morbidity and mortality in India. Though many comprehensive studies have been carried out in Africa and Southeast Asia to characterize and examine determinants of Plasmodium falciparum and Plasmodium vivax malaria pathogenesis, fewer have been conducted in India. Methods: A prospective study of malaria-positive individuals was conducted at Goa Medical College and Hospital (GMC) from 2012 to 2015 to identify demographic, diagnostic and clinical indicators associated with P. falciparum and P. vivax infection on univariate analysis. Results: Between 2012 and 2015, 74,571 febrile individuals, 6287 (8.4%) of whom were malaria positive, presented to GMC. The total number of malaria cases at GMC increased more than two-fold over four years, with both P. vivax and P. falciparum cases present year-round. Some 1116 malaria-positive individuals (mean age = 27, 91% male), 88.2% of whom were born outside of Goa and 51% of whom were construction workers, were enroled in the study. Of 1088 confirmed malaria-positive patients, 77.0% had P. vivax, 21.0% had P. falciparum and 2.0% had mixed malaria. Patients over 40 years of age and with P. falciparum infection were significantly (p < 0.001) more likely to be hospitalised than younger and P. vivax patients, respectively. While approximately equal percentages of hospitalised P. falciparum (76.6%) and P. vivax (78.9%) cases presented with at least one WHO severity indicator, a greater percentage of P. falciparum inpatients presented with at least two (43.9%, p < 0.05) and at least three (29.9%, p < 0.01) severity features. There were six deaths among the 182 hospitalised malaria positive patients, all of whom had P. falciparum. Conclusion: During the four year study period at GMC, the number of malaria cases increased substantially and the greatest burden of severe disease was contributed by P. falciparum