WWW.WAS.ORG • WORLD AQUACULTURE • SEPTEMBER 2016 37 Scylla and P. pelagicus (Parenrengi et al. 1993). Luminescent V. harveyi (CLM3) are pathogenic to zoea (Z1) of S. serrata, inducing mortality of 63-64 percent at an initial dose of 102 and 103 cfu/mL, compared to 40 percent mortality in the control (Lavilla-Pitogo et al. 2002). Infected larvae had plagues of bacteria on the mouth and feeding apparatus, implying an oral route of entry for the pathogen. The sources of luminescent V. harveyi were determined from different hatchery components (Lavilla-Pitogo et al. 1992). The bacterial flora of the midgut of broodstock contained 16-17 percent luminescent Vibrio populations and broodstock were significant sources of luminescent Vibrio. Broodstock crabs release large amounts of fecal material during spawning, thus facilitating bacterial colonization of newly spawned eggs. A second pathway for pathogenic bacteria to enter the culture environment of Scylla zoea is through live planktonic food as bacteria enter the digestive tract of larvae orally. Furthermore, the bacterial ecology of Scylla larval cultures are unstable between and within culture cycles, including changes in sucrose negative and positive Vibrio ratios. Constant high numbers of green (sucrose negative) Vibrio colonies on TCBS agar is regarded as a sign that high mortality is imminent. Lactobacillus used in aquaculture synthesizes proteases and amylases. In P. pelagicus, increased digestive enzyme activity of larvae in tanks receiving probiotics results in reductions of Vibrio in the gut of larvae and culture water, providing favorable conditions that contribute to improved larval survival and enzyme activities. Supplementation of Lactobacillus has an influence on the swimming behaviour of larvae, especially during the first days after hatching. Thalassobacter utilis (strain PM4) has been used to control V. harveyi and improve survival of larval swimming crab Portunus trituberculatus. Vibrio alginolyticus is an environmental probiotic that protects against vibriosis in Scylla. The strain V. alginolyticus LLB2 has been isolated and tested against a control in larval S. serrata, both challenged with V. harveyii (LLD1, pathogenic strain), with the treatment group giving a higher survival rate. The use of Bacillus and Lactobacillus as probiotics is an ideal alternative to antibiotics in crab hatcheries to provide a consistent, commercially feasible production of seedlings. Acknowledgements We acknowledge the staff and students of CEMACS, USM, including the staff of the Mud Crab Research Project, CEMACS. This work was funded by the APEX Delivering Excellence (1002/PPANTAI/910331, USM), Short Term Grant (304/ PPANTAI/6312131, USM), and the Post Graduate Research Grant Scheme (USM). The financial support of MyBrain15 (Ministry of Higher Education), and Graduate Assistant (USM) are equally acknowledged. Notes Kwong Kok Onn, Md. Arif Chowdury and Wan Mustaffa Wan Din, Center for Marine and Coastal Studies, Universiti Sains Malaysia, USM, 11800. Khairun Yahya, School of Biological Science, Universiti Sains Malaysia, USM, 11800. Anita Talib*, School of Distance Education, Universiti Sains Malaysia, USM, 11800. *Corresponding author: School of Distance Education, Universiti Sains Malaysia (USM), Pulau Pinang, Malaysia. Phone: +6046534574. FAX: +604-6576000. Email: anita@usm.my References Douilett, P.A. 1998. Disinfection of rotifer cysts leading to bacteriafree populations. Journal of Experimental Marine Biology and Ecology 224:183-192. Lavilla-Pitogo, C.R., L.J. Albright, M.G. Paner and N.A. Sunazm. 1992. Studies on the sources of luminescent Vibrio harveyi in Penaeus monodon hatcheries. Pages 157-164 In I. M. Shariff, R. P. Subasinghe and J. R. Arthur, editors. Diseases in Asian Aquaculture I, Proceedings of the First Symposium on Diseases in Asian Aquaculture, 26-29 November 1990, Bali, Indonesia. Manila: Asian Fisheries Society. Lavilla-Pitogo, C.R., D.D. Catedral, S.A.G. Pedrajas and L.D. De la Peña. 2002. Selection of probiotics for shrimp and crab hatcheries. Pages 136-150 In: Y. Inui and E.R. Cruz-Lacierda, editors. Disease Control in Fish and Shrimp Aquaculture in Southeast Asia – Diagnosis and Husbandry Techniques: Proceedings of the SEAFDEC-OIE Seminar- Workshop on Disease Control in Fish and Shrimp Aquaculture in Southeast Asia – Diagnosis and Husbandry Techniques, 4-6 December 2001, Iloilo City, Philippines. Iloilo: SEAFDEC Aquaculture Department. Parenrengi, A., Zafran, D.R. Boer and I. Rusdi. 1993. Identification and pathogenicity of various vibrios on the mangrove crab, Scylla serrata, larvae. Journal of Coastal Aquaculture 9(3):125-129. Talpur, A.D., A.J. Memon, M.I. Khan, M. Ikhwanuddin, M.M. Danish Daniel and A.B. Abol-Munafi. 2012. Isolation and screening of lactic acid bacteria from the gut of blue swimming crab, P. pelagicus, an in vitro inhibition assay and small scale in vivo model for validation of isolates as probiotics. Journal of Fisheries and Aquatic Sciences 7(1):1-28. Zokaeifar, H., J.L. Balcázar, M.S. Kamarudin, K. Sijam, A. Arshad and C.R. Saad. 2012. Selection and identification of non-pathogenic bacteria isolated from fermented pickles with antagonic properties against two shrimp pathogens. Journal of Antibiotics 65:289-294. FIGURE 6. Laboratory-cultured, Gram-stained Lactobacillus plantarum probiotic (100 x magnification).
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