Journal of Pure and Applied MicrobiologyVol. 8 No. May 2014 Special Edition

Algicidal Activities against Scrippsiella trochoidea and Prorocentrum micans by Bacillus sp. Strain N29 Isolated from Mirs Bay, China

Ming Dai1, Rongjun Shi1,2, Honghui Huang1*, Zhanhui Qi1, Weian Hu1,2 and Ziyang Tian1,2

1 Key Laboratory of Fishery Ecology and the Environment, Guangdong Province; Key Laboratory of South China Sea Fishery Resources Exploitation & Utilization, Ministry of Agriculture, P. R. China; South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510300, China. 2College of Marine Science, Shanghai Ocean University, Shanghai 201306, China.

Received on 12 April 2014 and accepted on 09 May 2014

 

ABSTRACT

A bacterial strain N29 was isolated from the sediment of Mirs Bay during Scrippsiella trochoidea bloom. By analysis of its morphology and biochemistry, as well as homology screening using 16S rRNA gene sequences, strain N29 was identified as Bacillus anthracis CEB95-0033. Strain N29 showed algicidal activities against S. trochoidea and Prorocentrum micans but had no effect on Skeletonema costatum and Phaeodactylum tricornutum. Moreover, the algicidal activity correlated with bacterial concentration, algal species and incubation period. More specifically, strain N29 had little algicidal effect at low volume fraction of 0.1% and 1% for S. trochoidea and P. micans, because of the densities of S. trochoidea and P. micans increased substantially just like the controls in the incubation period. However, after incubation of strain N29 with S. trochoideaat volume fraction of 1% and 2%, 100% of S. trochoidea cells were killed within 120 h and 96 h. Further, algicidal effect of strain N29 on P. micans required higher bacterial concentrations. For example, at 5% volume fraction, 85% of P. micans cells were killed within 120 h; at 10% volume fraction, 100% of P. micans were killed within 72 h. It showed that strain N29 had algicidal effect on S. trochoidea and P. micans in shorter incubation time with higher bacterial concentration. In addition, algicidal effects were checked with bacterial culture filtrates and heated filtrates of strain N29 on S. trochoidea or P. micans, which showed that they lysed P. micans but been ineffective on S. trochoidea. It implied that strain N29 killed P. micans by releasing some heat-tolerant algicide, but killed S. trochoidea via direct attack or competition for nutrients.

Keywords : Algicidal bacterium, Scrippsiella trochoidea, Prorocentrum micans, Mirs Bay.