During last decades there has been a continuous growth of aquaculture industries all over the world and taking into
consideration the spurt in freshwater ornamental fish aquaculture and trade in Kerala, the present study was aimed to assess the
prevalence of various motile Aeromonas spp. in fresh water ornamental fishes and associated carriage water. The extracellular
virulence factors and the antibiogram of the isolates were also elucidated. Various species of motile aeromonads such as Aeromonas
caviae, A. hydrophila, A. jandaei, A. schubertii, A. sobria, A. trota and A. veronii were detected. Aeromonas sobria predominated
both fish and water samples. Extracellular enzymes and toxins produced by motile aeromonds are important elements of bacterial
virulence. The production of extracellular virulence factors - proteases, lipase, DNase and haemolysin by the isolates were studied.
All the isolates from both fish and water samples produced gelatinase and nuclease but the ability to produce lipase, caseinase and
haemolysins was found to vary among isolates from different sources. Among the 15 antibiotics to which the isolates were tested, all
the isolates were found to be sensitive to chloramphenicol, ciprofloxacin and gentamicin and resistant to amoxycillin. Local aquarists
maintain the fish in crowded stressful conditions, which could trigger infections by the obligate/ opportunistic pathogenic members
among motile aeromonads
Description:
International Journal of Aquaculture, 2013, Vol.3, No.17, 92-100
Hatha, A A M; Jabir, T; Dhanya, V; Jesmi, Y; Prabhakaran, M P; Saravanane, N; Gupta, G V M(Hindawi Publishing Corporation, July 12, 2013)
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Abstract:
Symbiotic diatom-diazotrophic cyanobacteria association (DDA) of Rhizosolenia hebetata and Rhizosolenia formosa with
endosymbiotic cyanobacteria Richelia intracellularis was noticed and documented for the first time during a bloom of the
cyanobacterium Trichodesmium erythraeum in the oligotrophic shelf waters along Kochi and Mangalore transects, southeastern
Arabian Sea (SEAS), during spring intermonsoon (April 2012). Although the host is frequently seen, the symbiont is rarely reported
in the Indian EEZ. The presence of nitrogen-fixing symbiotic association of Rhizosolenia-Richelia along with Trichodesmium
erythraeum highlights the significance of DDAs on the nutrient and energy budgets of phytoplankton in the oligotrophic
environments of the Arabian Sea during spring intermonsoon
Description:
International Journal of Oceanography
Volume 2013, Article ID 350594, 6 pages
Hatha, A A M; Mujeeb Rahiman, K M; Jasmine, B; Suresh Kumar,S(International Journal of current microbiology and applied sciences, 2014)
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Abstract:
In natural systems phytoplankton interact with planktonic (free living) and attached
epiphytic bacteria both synergistically and antagonistically. The specificity of the
association with micro algae and bacteria differs in terms of adhesion mechanisms
and metabolic cooperation. Present research was carried out to study the effect of
bacterial isolates namely Bacillus sp. and Pseudomonas sp. from algal culture
systems on the growth of micro algae such as Chaetoceros calcitrans and
Nannochloropsis oculata. C. calcitrans (F= 15.34; P<0.05) and N. oculata
(F=12.52; P<0.05) showed significantly higher growth, in treatments with Bacillus
sp. and Pseudomonas sp when compared to control.
Hatha, A A M; Shubhankar Ghosh; Einar, RingØ2; Deborah Gnana Selvam, A; Mujeeb Rahiman, K M; Naveen, Sathyan; Nifty, John(Sophia, January 22, 2014)
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Abstract:
In the present study we address the issue on gut associated lactic acid bacteria (LAB) isolated from the intestine of
estuarine fish Mugil cephalus using de Man Rogossa and Sharpe (MRS) agar. LAB isolates were identified biochemically and
screened for their ability to inhibit in vitro growth of various fish, shrimp and human pathogens. Most of the LAB isolates displayed
an improved antagonism against fish pathogens compared to shrimp and human pathogens. Selected representative strains displaying
high antibacterial activity were identified using 16S rRNA gene sequence analysis. Of the selected strains Lactobacillus brevis was
the most predominant. Four other species of Lactobacillus, Enterobacter hormaechei and Enterobacter ludwigii were also identified.
It was also observed that even among same species, considerable diversity with respect to substrate utilization persisted. Considering
the euryhaline nature of grey mullet (Mugil cephalus), the LAB isolated from the gut possessed good tolerance to varying salt
concentrations. This finding merits further investigation to evaluate whether the isolated LAB could be used as probiotics in various
fresh and sea water aquaculture
Description:
International Journal of Aquaculture, 2014, Vol.4, No.01