Disease outbreak is increasingly recognized as a significant constraint to aquaculture production and trade. Bacterial
infections are part of the causes of mortality in fish. Use of antibiotics resulted in resistant strain of bacteria in fish. The use of
lactobacillus as probiotics is now being investigated as alternative. Studies were carried out to isolate and identify probiotics from
the guts of Sphyraena Sphyraena (Marine water), Chrysisthys nigrodigitatus (brackish water) and Clarias gariepinus (freshwater).
Guts removed from dissected fishes were divided into 3 regions: foregut, midgut and hindgut. These samples were mixed
homogeneously in sterilized phosphate buffer saline (PBS) separately and allowed to pour in MRS broth and agar medium.
Lactobacillus was isolated from fish guts using MRS agar and broth. There was subsequent culture and subculture of lactobacillus
to obtain discrete colonies. Single colony of lactobacillus was isolated using colony morphology and some biochemical tests. The
identity of the culture was determined by using Bergey?s manual of Determinative bacteriology, (API- 50 CHL, BioM?rieux).
Bacteria isolated from the foregut, midgut and hindgut were identified as Lactobacillus brevis and Lactobacillus plantarum
from Sphyraena Sphyraena (Marine water), Lactobacillus plantarum and Lactobacillus pentosus from Chrysisthys nigrodigitatus
(brackish water) and Lactobacillus plantarum, Lactobacillus pentosus and Lactococcus lactis ssp lactis 1 from Clarias gariepinus
(freshwater). Population level of bacteria was higher in the midgut and hindgut region than observed in the foregut region.
Microscopically they were Gram-positive, rod shaped, non- motile, catalase negative and absence of Endospore. The isolates
would be evaluated for fish feed supplement as probiotics.
Caroline Ayo-Olalusi is a research scientist at the Department of fish technology, Nigerian Institute for Oceanography and Marine Research Lagos,
Nigeria. She is a fish Nutritionist specializes in fish feed production from locally available fish feed ingredients. She has published extensively
in reputable journals. She is currently a PhD student at the University of Ibadan, Ibadan. Nigeria. She has recently won a research grants from
Agricultural research council of Nigeria on the ?Potential benefits of probiotics on the immune response and growth of some culturable fish species?
where she is the Principal Investigator. She has attended many conferences and workshops.
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