Streptococcus iniae infection in cultured Asian sea bass (Lates calcarifer) and red tilapia (Oreochromis sp.) in southern Thailand

Streptococcal infections are becoming an increasing problem in aquaculture and have been reported worldwide in avariety of fish species. Here we describe the isolation and characterization of Streptococcus iniae from Asian sea bass (Latescalcarifer) and red tilapia (Oreochromis sp.) cultured in southern Thailand. Conventional and rapid identification systems,as well as the polymerase chain reaction (PCR), were used to determine that the isolate was S. iniae. The virulence of thisS. iniae was higher in Asian sea bass than in red tilapia, as shown by the 10 day-LD50 in Asian sea bass and red tilapia, being1.08x104 and 1.14x107 CFU, respectively. Histopathological changes in Asian sea bass are more severe than those observedin red tilapia. The changes can be found in several organs including liver, pancreas, heart, eye and brain. Histopathologicalfindings included cellular necrosis, infiltration of lymphocytes and granuloma formation in the infected organs

Isolation and production of prodigiosin and cycloprodigiosin from marine sponges-associated bacteria of the Andaman coast of Thailand

During October 2015 to December 2016, eight marine sponge-associated bacteria (PSU-KSAAHRC MS1-8) with red, reddish orange, yellow, reddish pink, and dark red pigments were isolated from five species of marine sponge, namely Callyspongia sp., Callyspongia diffusa, Haliclona sp., Dysidea sp. and Stylissa carteri, sampled from Satun and Phang-Nga provinces on the Andaman coast of Thailand. These bacteria produced pigments in the range 55.65-5,619.67 µg/g. The highest pigment content was found in the dark red-pigmented bacterial isolate PSU-KSAAHRC MS2 isolated from Haliclona sp. sampled in Satun province. Thin layer chromatography of a red amorphous pigment extract from the bacterial isolate PSUKSAAHRC MS2 revealed two fractions with respective Rf value of 0.65 and maximum absorbance at 535, and Rf value of 0.57 and maximum absorbance at 539 nm. Analyses of each TLC fraction by liquid chromatograph quadrupole time of flight mass spectrometer revealed the molecular weights of 323 (m/z 324, [M+H]+ ) and 321 (m/z 322, [M+H]+ ), in the same order. Comparing to published data, the compound with maximum absorbance at 535 and molecular weight of 323 (m/z 324, [M+H]+ ) was identified as prodigiosin while the compound with maximum absorbance at 539 nm and molecular weight of 321 (m/z 322, [M+H]+ ) was identified as cycloprodigiosin. Based on morphological and biochemical characteristics as well as phylogenetic analysis obtained from the present study, the bacterial isolate PSU-KSAAHRC MS2 was identified as Zooshikella sp. To our knowledge, this is a first report on identification of prodigiosin and cycloprodigiosin from Zooshikella sp. isolated from marine sponge, Haliclona sp., in Thailand

Multiplex PCR for simultaneous detection of Streptococcus agalactiae, Streptococcus iniae and Lactococcus garvieae: a case of S. agalactiae infection in cultured Nile tilapia (Oreochromis niloticus) and red tilapia (Oreochromis niloticus x Oreochromis mossambicus)

A multiplex PCR (m-PCR) technique was developed for simultaneous detection of the causative agents responsible forstreptococcosis of cultured fish in Thailand i.e., Streptococcus agalactiae, Streptococcus iniae, and Lactococcus garvieae.The study on the sensitivity of the technique indicated that the minimum detected DNA concentration was 9.76, 39.06, and19.53 pg for S. agalactiae, S. iniae and L. garvieae, respectively. Detection of streptococcosis in healthy and diseased Niletilapia (Oreochromis niloticus) and red tilapia (Oreochromis niloticus x Oreochromis mossambicus) cultured in Paphayomand Bangkaew District, Phatthalung Province and Sichon and Hua Sai District, Nakhon Si Thammarat Province, Thailand, bym-PCR technique showed positive results for S. agalactiae from tilapia cultured in Bangkaew and Hua Sai and negativeresults for samples from Paphayom and Sichon. The m-PCR results were in accordance with microbiological culture techniques,which detected S. agalactiae from tilapia cultured in Bangkaew and Hua Sai indicating that our m-PCR assay is a sensitiveand specific diagnostic tool for simultaneous detection of streptococcosis caused by S. agalactiae, S. iniae and L. garvieaein cultured fish in Thailand