Predatory bacteria in the haemolymph of the cultured spiny lobster .

and like organisms (BALOs) are Gram-negative obligate predators of other bacteria in a range of environments. The recent discovery of BALOs in the circulatory system of cultured spiny lobster warrants more investigation. We used a combination of co-culture agar and broth assays and transmission electron microscopy to show a sp. strain Hbv preyed upon the model prey bacterium sp. strain Vib. The haemolymph microbiome of juvenile was characterised following injection of phosphate buffered saline (control) or prey and/or predator bacteria for 3 d. The predator Hbv had no effect on survival compared to the control after 3 d. However, when compared to the prey only treatment group, lobsters injected with both prey and predator showed significantly lower abundance of genus in the haemolymph bacterial community composition. This study indicates that predatory bacteria are not pathogenic and may assist in controlling microbial population growth in the haemolymph of lobsters.