The Effects Of Bacillus And Lactobacillus As Probiotics On Mud Crab Scylla Paramamosain (Estampador, 1949) Zoea Larval Culture Performance

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Date
2016-03
Authors
Kwong, Kok Onn
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Universiti Sains Malaysia
Abstract
Mud crabs (Scylla spp.) are commercially important crustaceans. One of the major obstacles to the growth of Scylla aquaculture is the low supply of hatchery produced seed due to bacterial diseases and high rates of mortalities. Currently, antibiotics are used extensively in Scylla larval culture to improve survival, but its use poses numerous risks including the development of resistance in bacteria to antibiotics, higher levels of virulence, and detection of restricted chemicals in the flesh of farmed animals. The aim of this study was to determine the culture performance of Scylla paramamosain larvae with the use of three different types of probiotics, namely a multispecies Bacillus, Lactobacillus casei (Shirota), and Lactobacillus plantarum, at various concentrations. There were higher average larval survivals in treatments with a multispecies Bacillus probiotics added compared with the control, especially at concentrations of 5.00 × 108 (12.33 - 18.33 ± 1.76 - 3.76 % compared to 1.67 - 3.67 ± 1.67 - 1.76 %; P < 0.05) and 1.00 × 109 cfu/ml. The best concentration of the multispecies Bacillus probiotic that gave lower Vibrio parahaemolyticus counts in this study was at a concentration of 1.00 × 109 cfu/ml. This was significantly lower than the control (1.33 ± 1.33 cfu/ml compared to 32.67 ± 11.05 cfu/ml) during the later days post hatching (DPH). Vibrio parahaemolyticus is known to be pathogenic to Scylla larvae, thus lower numbers are desirable in culture. On average, there were no obvious differences in water qualities and Larval Stage Indexes (LSIs) between the multispecies Bacillus treatments and controls, although larvae appeared healthier in the multispecies Bacillus treatments. Water qualities were within tolerable ranges for Scylla larvae. The fastest larval developmental stage was seen in the multispecies Bacillus treatment at 1.00 × 109 cfu/ml. Lactobacillus casei treatments at concentrations of 1.88 × 108 and 3.75 × 108 cfu/ml gave significantly higher survival rates compared to the control during the early to mid DPHs (49.70 - 99.30 ± 11.90 - 29.20 and 70.70 ± 13.03 % compared to 2.30 - 5.70 ± 1.20 - 5.70 %, respectively; P = 0.022 and 0.029). There were significantly higher survival rates in the Lactobacillus plantarum treatments compared to the control during the early DPH (74.33 - 90.67 ± 7.26 - 6.57 % compared to 47.67 ± 2.19 %; P = 0.040 and 0.005), at concentrations of 1.00 × 102 and 5.00 × 102 cfu/ml in the culture water. In terms of water qualities and LSIs, there were no obvious differences between the Lactobacillus treatments and controls, and this could be due to the relatively low concentration of Lactobacillus added. Based on the concentrations used in this study, the multispecies Bacillus probiotic was more effective than single species Lactobacillus for improving the survival rate and lowering V. parahaemolyticus counts of S. paramamosain larvae. The recommended concentration of the multispecies Bacillus to be added into S. paramamosain larvae was therefore 5.00 × 108 and 1.00 × 109 cfu/ml, and for Lactobacillus it was 3.75 × 108 cfu/ml. The use of Bacillus and Lactobacillus as probiotics is an ideal alternative to antibiotics in Scylla hatcheries to provide a consistent, commercially feasible production of seedlings.
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Mud crabs
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