A feeding experiment was conducted to investigate the effect of Bacillus subtilis bacterium, on larval growth and development rate of Macrobrachium rosenbergii (de Man) during February 28 to April 8, 2005 in University Putra Malaysia hatchery. Newly hatched larvae of M. rosenbergii were reared with two dietary treatments consisting of newly hatched Artemia salina nauplii with B. subtilis (108 cells ml−1), and newly hatched A. salina nauplii without B. subtilis carried out in triplicate in 60‐L aquarium (50 L−1). After trial, the larvae that fed B. subtilis‐treated Artemia naupli were found to have higher survival and a faster rate of metamorphosis than larvae that were fed with nontreated Artemia naupli. There were significant differences between B. subtilis‐treated Artemia naupli and nontreated Artemia diet in larval growth and development rate of metamorphosis (P < 0.05). Larval survival after 40 days was significantly greater (P < 0.05) in the B. subtilis‐treated groups (55.3 ± 1.02) compared with the nontreated groups (36.2 ± 5.02%).

This experiment was carried out to investigate the potential probiotic properties of Bacillus subtilis and suitable methods of administration to the commercial feed in juvenile Macrobrachium rosenbergii (de Man) from 25 August to 25 November 2008. Putative Bacillus subtilis bacterium isolated from juvenile M. rosenbergii intestine was added to commercial prawn feed as a probiotic. Five types of diets were prepared by mixing B. subtilis at level of 108 cells g -1 with commercial feed using different methods consisting mixing, soaking, spraying and bathing. After 60 days, the prawns fed diets at soaking method treated group, showed a higher mean weight gain (2.09) or 328.84% increase in growth over control. There were significant differences (P \ 0.05) in weight gain, feed intake and FCR among soaking method and other treated and control groups. There was significant difference (P \ 0.05) in survival among treated and control groups, but no significant difference (P [ 0.05) in water quality and biochemical composition among treated and control groups. Clearly, B. subtilis-treated diets appeared to enhance growth and survival of juveniles M. rosenbergii. It was concluded that the tested strain may be a promising probiotic for M. rosenbergii under soaking method of administration to the prawn commercial feed.

This experiment was carried out to investigate the potential probiotics properties of Bacillus subtilis in protecting of juvenile freshwater prawn, Macrobrachium rosenbergii against Aeromonas hydrophila infection. A B. subtilis bacterium isolated from gut of juvenile prawns was added to the prawns feed at 10 8 cells g -1 feed. There were significant differences (P \ 0.05) between B. subtilis-treated and control groups in growth and survival enhancement of juvenile prawns after 60 days of feeding trial. Sixty days after B. subtilis feeding trial, the prawns were challenged by bath exposure to A. hydrophila (10 7 cells mL -1 ) for 28 days. Four weeks after challenge, there was significant difference in the survival of prawns between B. subtilis-treated groups (88.33 %) and control groups (20.81 %; P \ 0.05). In addition, the control groups had an unhealthy external appearance, while the treated groups, appeared healthy and normal. From this, it was concluded that the selected B. subtilis may be a promising probiotics for protection of prawns from A. hydrophila infection.

No abstract