Dynamic shifts and functional insights into bacterial communities during the aplanospore stage of Haematococcus lacustris

Abstract

Haematococcus lacustris is an important natural source of astaxanthin for the pharmaceutical and nutraceutical industries. However, its slow growth and susceptibility to contamination by other microalgae pose challenges for commercial astaxanthin production. The bacterial communities associated with microalgae can affect biomass yield and the production of value-added compounds. This study explored the dynamic shifts and functional characteristics in the microbial communities associated with H. lacustris during the aplanospore stage using 16S rRNA metabarcoding. As H. lacustris reached the aplanospore stage, the bacterial communities underwent significant shifts. At the genus level, Massilia dominated the early stages but was later replaced by Sphingomonas in both the microalgae-attached and particle-attached bacterial communities. In contrast, Sphingomonas dominated free-living bacterial communities. Functional predictions suggest that these bacterial communities may support the cultivation of H. lacustris by potentially supplying essential growth factors, including auxins, vitamins, and heme. Network analysis identified that Sphingomonas species can be a key regulator of the microbiome of H. lacustris culture, facilitating the development of H. lacustris during the inductive stage. Overall, these findings highlighted the potential role of the microbiome in supporting the development of H. lacustris at this stage.