Prochlorococcus is a significant marine cyanobacterium. Credit: Luke Thompson (Chisholm Lab), Nikki Watson (Whitehead), MIT
Synechococcus in the coastal waters of the Andaman archipelago have more photosynthetic pigment-related genes than in the open ocean Prochlorococcus, the other most prolific photosynthetic cyanobacteria. This shows that Synechocuccus have adapted to light stress, according to new research1.
Single-celled Synechococcus and Prochlorococcus are responsible for a significant fraction of photosynthesis in oceans. An ability to cope with changing light quality is crucial for their survival.
Scientists at the Indian Institute of Science Education and Research Bhopal in Madhya Pradesh explored the islands’ coastal water microbiome using 16S rRNA gene amplicon and metagenomic shotgun sequencing. They compared the coastal samples with select open ocean samples collected by the Tara Oceans Consortium, the largest marine microbe genetic sequencing project.
The Synechococcus species was significantly more abundant in Andaman coastal water compared with open ocean samples, while Prochlorococcus genomes were more abundant in open ocean.
Coastal waters had more of the psbA gene, which makes the D1 protein in the Synechococcus light-harvesting unit. This gene is highly expressed in Synechococcus sp. WH7803 under changing light, indicating its light-stress resilience. Fewer light-harvesting genes in Prochlorococcus suggest that it is adapted to the more stable light conditions of the open ocean.
The waters around the islands are also teeming with genes that confer resistance to aminoglycoside, beta-lactam and tetracycline antibiotics.
The scientists have added 93,172 unique genes from the Andaman region to the Ocean Microbial Reference Gene Catalog. These could potentially be used in biotechnology and to monitor antibiotic resistance risks.
