Identification of multi-antibiotic resistant bacteria isolated from Vietnamese climbing perch (Anabas testudineus) on fish farms in Ho Chi Minh City, Vietnam

Climbing perch (Anabas testudineus) is considered a cultured species with high economic value and is widely distributed in several Asian countries, including Vietnam. In climbing perch aquaculture, antibiotic and antibacterial agents have been overused, leading to the emergence of antibiotic-resistant bacteria or genes in the aquatic environment as well as in the seafood products. These antibiotic-resistant bacteria and/or genes can then be spread to human through the food chain, generating detrimental consequences for public health and environment. In this study, 14 bacterial strains were isolated from Vietnamese climbing perch collected from various fish farms in Ho Chi Minh City which possess abnormal symptoms on the outside and in their organs. These bacterial strains were then subjected to several biochemical tests to characterize their colony morphologies. Besides, gene sequencing was performed and as compared to the 16S rRNA, 4 bacterial strains were identified with a high percentage in similarity, including Pseudomonas aeruginosa (99.7%), Aeromonas caviae (99.93%), Kosakonia sacchari (100%), and Edwardsiella ictaluri (99.44%). Additionally, these bacteria showed high levels of antibiotic resistance against beta-lactam, tetracycline, and others. Taken together, these results showed that the four identified bacterial strains isolated from Vietnamese climbing perch circulated in fish farms in Ho Chi Minh City. Their current status of multi-antibiotic resistance indicates further alternative sources of antimicrobial agents, for example, natural compounds, to overcome antibiotic resistance. It is then crucial to identify fish diseases, the associated pathogens, and the new alternatives for antibiotics to protect aquatic ecosystems and water resources.

Anti-breast cancer synthetic peptides derived from the Anabas testudineus skin mucus fractions

Previous study has shown the antimicrobial activities of mucus protein extracted from Anabastestudineus. In this study, we are interested in characterizing the anticancer activity of the A.testudineus antimicrobial peptides (AMPs). The mucus was extracted, fractioned, and subjected to antibacterial activity testing to confirm the fish's AMPs production. The cytotoxic activity of each fraction was also identified. Fraction 2 (F2), which shows toxicity against MCF7 and MDA-MB-231 were sent for peptide sequencing to identify the bioactive peptide. The two peptides were then synthetically produced and subjected to cytotoxic assay to prove their efficacy against cancer cell lines. The IC50 for AtMP1 against MCF7 and MDA-MB-231 were 8.25 ± 0.14 μg/ml and 9.35 ± 0.25 μg/ml respectively, while for AtMP2 it is 5.89 ± 0.14 μg/ml and 6.97 ± 0.24 μg/ml respectively. AtMP1 and AtMP2 treatment for 48 h induced breast cancer cell cycle arrest and apoptosis by upregulating the p53, which lead to upregulate pro-apoptotic BAX gene and downregulate the anti-apoptotic BCL-2 gene, consequently, trigger the activation of the caspase-3. This interaction was supported by docking analysis (QuickDBD, HPEPDOCK, and ZDOCK) and immunoprecipitation. This study provided new prospects in the development of highly effective and selective cancer therapeutics based on antimicrobial peptides.

ACETYLCHOLINESTERASE, AS A POTENTIAL BIOMARKER OF NAPHTHALENE TOXICITY IN DIFFERENT TISSUES OF FRESHWATER TELEOST, ANABAS TESTUDINEUS

Naphthalene, a Polycyclic Aromatic Hydrocarbon is widely used as a fumigant and disinfectant despite its toxic effect and is ranked as the ninth most threatening compound. The present study was carried out to determine the in vivo effect of naphthalene at different concentrations on acetylcholinesterase (AChE) enzyme activity in different tissues of Anabas testudineus. The fishes were exposed to varying concentrations of naphthalene (4.2 mgL–1, 4.4 mgL–1, 4.6 mgL–1, 4.8 mgL–1 and 5 mgL–1) for a period of 72 hours. Acetylcholinesterase enzyme activity was found to be significantly inhibited, in a dose-response manner. The inhibition percentage of AChE activity varied from 9.34–43.95% in brain tissue, 2.56–35.81% in liver tissue, 5.94–34.15% in muscle tissue and 3.92–33.75% in gills in comparison to the tissues of the control group. Maximum inhibition of acetylcholinesterase enzyme activity in treated fish was observed in the brain followed by liver, muscles, and gills. This study highlights the significance and role of acetylcholinesterase as a potential stress biomarker of naphthalene toxicity.

Taxonomical Accounts of Protozoan Parasites of Climbing Perch, Anabas Testudineus in Bangladesh

The study was conducted to identify the protozoan parasites in a freshwater indigenous air breathing fish, Anabas testudineus. The host fish was collected during mid of the April 2018 to end of the March 2019 from freshwater bodies of Mymensingh, Kishoregonj, Faridpur, Jashore, Manikganj and Bogura districts of Bangladesh. Five species of phylum myxozoa namely Henneguya gigas, Henneguya mystusia, Henneguyaa cerinae, Henneguya periophthalmusi and Myxidium sp., three species of phylum ciliophora namely Amphileptus disciformis, Epistylisl woffi and Trichodina anabasi and one species of phylum mastigophora namely Trypanosoma anabasi were identified in A. testudineus. Myxozoans (97.55%) were clearly dominant group than chiliophorans (2.45%). Bangladesh J. Zool. 49 (2): 331-345, 2021

Interactive effects of dietary protein and lipid on growth of Indian climbing perch, Anabas testudineus fry

Aim: To assess the optimum protein and lipid requirement of Anabas testudineus at its fry stage, based on the growth performance, feed efficiency and nutrient gain efficiency. Methodology: Eight experimental diets were prepared with four protein (35, 40, 45 and 50 %) and two lipid (9 and 13%) levels. The diets were designated as D1 (35 P/9L), D2 (35 P/13 L), D3 (40 P/9 L), D4 (40 P/13 L), D5 (45 P/9 L), D6 (45 P/13 L), D7 (50 P/9 L) and D8 (50 P/13 L). Each of the experimental diets was fed to triplicate groups of 10 fishes with an average individual body weight of 1.23 g in 24 glass aquaria. The diets were fed at about 4 % body weight per day in two equal rations for a period of 60 days. Results: Significantly (p<0.05) higher weight gain (428 %), specific growth rate (2.77 % day-1), feed efficiency ratio (0.69) and protein efficiency ratio (2.34) and lower (p > 0.05) food conversion ratio (1.45) was observed in fish fed with diet D5 (45% protein and 9% lipid). The nutrient retention parameters like protein retention, protein productive value, lipid productive value and apparent net protein utilization were also significantly (p < 0.05) high in the treatment group D-5 fed with diet containing 45% protein and 9% lipid. Significantly (P<0.05) higher whole body protein content was observed in the treatment group D5 (45% protein / 9% lipid) along with D4 and D6. Interpretation: The present findings on optimum protein and lipid requirement of 45% and 9%, respectively will help in formulating the cost-effective practical diets for Anabas testudineus fry, which is essentially required for quality seed production and grow out culture of this species in a commercial scale.