Instrumental use of Marine Bacteria to Stimulate Growth in Seaweed

Abstract

Edible seaweed - Caulerpa lentillifera is being cultivated along the coast of Khanh Hoa province, Vietnam, and makes a relatively large contribution to the economic development of this region. Bacterial strains originating from marine sources such as those associated with seaweed and hard coral were screened for properties of promote plant growth with the capacity of indole-3-acetic acid (IAA) - a phytohormone belonging to auxin group, the phosphate solubilization ability and antibacterial activity of IAA-producing strains were also performed in this study. Robust strains were identified by morphological methods with biochemical tests and analysis of 16s RNA sequences. Isolate RN06 produced high amounts of IAA, utilized inorganic phosphate, and inhibited Bacillus subtilis ATCC6633, Escherichia coli 0157, and Serratia marcescens PDL100. The IAA producer HRA5 isolated from hard coral demonstrated the ability to solubilize phosphate and exhibited antibacterial activity against B. subtilis. Morphological analysis and 16sRNA sequencing showed that isolate RN06 was the closest strain to Bacillus amyloliquefaciens and HRA5 was linked to Pseudomonas sp. This is the first report of isolated bacteria from seaweed and corals from the Vietnamese sea served as potential strains for further research of the application of biological inoculants specifically for seaweed farming.