Large-scale production of an abalone probiotic, Vibrio midae, isolated from a South African abalone, Halitotis midae for use in aquaculture

Abstract

The South African abalone industry is under severe pressure due to illegal harvesting and poaching of this seafood delicacy. These abalone are harvested excessively and consequently, these animals do not have a chance to replace themselves, ensuing in a drastic decrease in natural abalone stocks. Abalone, has an extremely slow growth rate, and takes approximately four years to reach a size that is marketable. Probiotics offer a viable treatment solution to improve the growth, health and vigour of these animals. Two microorganisms, a yeast isolate Debaryomyces hansenii and a bacterial isolate Vibrio midae, from the gut of the South African abalone were characterised for their probiotic abilities. This work resulted in an internationally competitive concept technology that was patented. Thereafter research was focussed on developing a suitable bioprocess to enable commercial production of one the isolates, V. midae. During this development, production parameters such as temperature and pH, as well as alternative medium additives, such as the use of corn steep liquor (CSL) and high test molasses (HTM) was assessed. Once a high efficiency production process was developed at laboratory scale, this up- and downstream production technology was scaled up to manufacturing scale, which resulted in a final market ready probiotic product. The optimization of the key variables resulted in a 180% increase in cell concentration and a 5716-fold increase in cell productivity, in comparison to conventional growth conditions and parameters used at the beginning of the study.