Silvia Blanco1, Cecilia Pascelli1, Scott Cummins1, Nicholas Paul1 & Alex Campbell1
1 UniSC Seaweed Research Group, University of the Sunshine Coast, 90 Sippy Downs drive, QLD, Australia
Asparagopsis farming is set for major global expansion because of the effect of its halogenated compounds on methanogens when fed to cattle. However, some of the earliest work on this genus involved basic research into how these antimicrobial compounds benefit the seaweed itself by controlling the microbiome. In a systematic review, we show that after this brief window of research, which produced 35 papers on culture, microbes, and chemistry in the 1950-70s, most of the recent work has focussed on the addition of Asparagopsis to cattle feed and its cultivation for the same application (130 publications and counting). None of the current cultivation work has linked production constraints to the control of the microbiome and/or the importance of morphogenesis-promoting factors. These could be crucial for the healthy development of Asparagopsis in nature and in culture. In this study, we demonstrate that domesticated sporophytes have very specific microbiomes when compared to wild ones, and we explored the effects of microbiome manipulation using antibiotics on the growth rates of fast-growing seaweed cultures (weekly SGR 5%, >3 months). 16S rRNA gene sequencing and fluorescence microscopy were used to quantify the microbiome impacts. Different bacteria from the surface of the seaweed were identified by Sanger sequencing, including strains from Alteromonas and Roseobacter genera. We present the growth effects of various bacterial strains when reinoculated onto A. taxiformis, as well as their impact on the production of the halogenated compounds. These are discussed in the context of the future success of farming enterprises.