3 research outputs found
Antimicrobial activity of mesophilic and psychrotropic microfungi isolates from: king george island and greenwich island, maritime antarctica / Wessam Mansour Filfilan
This research was made to study the antimicrobial activity of fungal isolates from different regions of maritime, Antarctica, namely, King George Island and Greenwich Island (Barrientos Island, Dee Island and Ambato point). A total of 17 isolates composed of 7 mesophilic and 10 psychrotrophic fungi were tested in-vitro against Gram-positive, Gram-negative bacteria and yeast human pathogens. Initial antimicrobial activity screening of Antarctic isolates was made using plug assay method. Five test-microorganisms namely Candida albicans, Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa were used. Only five (out of 17) fungal isolates showed inhibition potency against the test-microorganisms and majority showed antibacterial activity rather than antifungal activity. Of these five species, three were psychrotrophic and two were mesophilic fungi. It should be pointed out that only two of the screened isolates inhibited the growth of Candida albicans despite the clearing zone diameter was smaller than 20mm. Based on these result, the five fungal isolates with good inhibition potency were selected for further studies. These species were then tested against large number of test-microorganisms by disc diffusion method. That showed only two fungal strains Penicillium sp. 20 and Deuteromycete sp. 25 have antibacterial activity against P. aeruginosa and B. cereus. Later, quantification assay using broth microdilution method was performed to determine the minimum inhibitory concentration (MIC) that showed from 12.5-25 mg/ml, minimum bactericidal concentration (MBC) showed between 25–1.56 mg/ml and minimum fungicidal concentration (MFC). The break point of minimum inhibitory concentration (MIC) was confirmed using indicator dye and both minimum bactericidal concentration (MBC) and
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minimum fungicidal concentration (MFC) were confirmed by sub-culturing from the different dilutions of crude extract
Histological Changes in the Gills of Marine Cultured Tilapia (Oreochromis spilurus) at Larvae Stage Treated by Phenanthrene
Background and Objective: Phenanthrene (PHE) is a constituent of polycyclic aromatic hydrocarbon (PAH), considered as one of the most abundant marine pollutants. It is mainly derived from pyrogenic and petrogenic sources. The aim of this study was to investigate the histological changes in gill’s structure of marine cultured tilapia fish larvae (Oreochromis spilurus).
Methodology: The larvae of the tilapia were fed phenanthrene contaminated feed twice a day for 14 days; the experiment was terminated on Day 14. The effect of phenanthrene on the gill’s structure was noticed and compared to the control group.
Results: There were noticeable histological changes on gills after treatment including; hypertrophy and fusion of the secondary lamellae. The mucus cell numbers in gill’s sections increased in the group treated with 100 mg L-1 of phenanthrene until the termination of the experiment. Conclusion: The deleterious effect of phenanthrene on gills histology was evidence at 100 mg L-1 and further studies are recommended on the histological effects of phenanthrene on other tissues of the tilapia fish.
Retraction Notice: This paper has been retracted from the journal after receipt of written complains. This journal is determined to promote integrity in research publication. This retraction is in spirit of the same. After formal procedures editor(s) and publisher have retracted this paper on 27th June-2019. Related policy is available here: http://goo.gl/lI77N
Whole Genome Sequence of the Newly Prescribed Subspecies Oreochromis spilurus saudii: A Valuable Genetic Resource for Aquaculture in Saudi Arabia
Tilapia (Oreochromis spp.) have significant potential for aquaculture production around the world. There is an increasing demand among tilapia producers for strains with higher yields and for fish that can survive in highly saline water. Novel strains and consistent seedstock are critically important objectives for sustainable aquaculture, but for these required targets there is still not enough progress. Therefore, this study describes the genome sequence of Oreochromis spilurus to support the seawater culture of tilapia. The draft genome is 0.768 Gb (gigabases), with a scaffold N50 (the genome (50%) is in fragments of this length) of 0.22 Mb (megabases). The GC content is 40.4%, the heterozygosity rate is 0.35%, and the repeat content is 47.97%. The predicted protein-coding peptide encoded 51,642 and predicted 10,641 protein-coding genes in the O. spilurus genome. The predicted antimicrobial peptides were 262, bringing new hope for further research. This whole genome sequence provides new insights for biomedical and molecular research and will also improve the breeding of tilapia for high yields, resistance to disease, and adaptation to salt water