Abalone are known to have a very slow growth rate that results in significant financial constraints for its cultivation. Commercially farmed abalone which are given formulated feed consisting of soy flour and seaweed still require 4 to 5 years to attain a market size of (80-100 mm) for shell length.

To improve growth in farmed New Zealand abalone (paua), Haliotis iris, potential probiotic isolates were isolated from healthy adult abalone obtained from OceaNZ Blue (Bream Bay, New Zealand) and from farm tanks. The isolates were screened qualitatively according to their ability to hydrolyze feed nutrients (such as proteins, starch, and alginate), produce lactic acid, and resist bile salts. Phenotypic and 16s rRNA techniques were used to identify the potential probiotic isolates. Biochemical analyses to determine which isolate exerted the strongest proteolytic, amylolytic, and alginolytic activities were carried out.

This study has developed a multi-strain conglomerate of 2- and 3- probiotic bacterial strains that have been supplemented into a commercial abalone feed to determine if probiotic microorganisms can increase the growth rate of farmed H. iris. The 2-probiotic conglomerate consisted of Exiguobacterium JHEb1 and Vibrio JH1, the 3-probiotic conglomerate consisted of Enterococcus JHLDc in addition to Exiguobacterium JHEb1 and Vibrio JH1.

The probiotic feeds were used in a laboratory feeding trial involving abalone juveniles (sized 20-30 mm) to determine if probiotic microorganisms can increase the growth rate of farmed H. iris. Two groups of abalone (in 3 replicates) were fed 2- probiotic supplemented, and 3- probiotic supplemented feed were compared with the control group (3 replicates) administered with un-supplemented feed. Proximate analysis of abalone faeces were performed to determine differences in proteins, carbohydrate, and lipid in all abalone groups and determine if these nutrients were more efficiently metabolized in the presence of probiotic bacteria.

A significant growth improvement was obtained with the 3-probiotic supplemented feed that produced a significant shell length increase of 20.9%, wet weight gain of 19.8% and reduced mortality (3.33%) (p<0.05). The 2-probiotic supplemented feed also resulted in significant increase in shell length and survival (p<0.05) but not in weight gain.

This study is the first to report of the application of Exiguobacterium JHEb1in abalone. This species was incorporated in both the 2-probiotic and the 3-probiotic feeds. This study is also the first to report that a combination of three probiotic species supplemented into the commercial feed of farmed H. iris increased growth measured by shell length and wet weight.