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News — SYRACUSE, N.Y. – Oct. 18, 2024 – Scientists at the SUNY College of Environmental Science and Forestry (ESF) have developed genetic engineering tools to better understand the role of actinobacteria in freshwater environments.

Their findings are published in the paper “Genome Editing in Ubiquitous Freshwater Actinobacteria,” featured in Applied and Environmental Microbiology (AEM).

Dr. Julia Maresca described actinobacteria as tiny, elbow macaroni-shaped organisms. “They're very cute, and they are found in every type of freshwater environment on Earth,” Maresca, associate professor in ESF’s Department of Chemistry said. “We see them in pristine mountain lakes, rivers, bogs, and ponds—freshwater environments are incredibly diverse.”

Actinobacteria are predominantly found in freshwater, not saltwater, suggesting a unique adaptation to freshwater ecosystems. Despite their small genome (1,500–1,800 genes compared to the 3,000 genes typical in most bacteria), they are globally successful, always thriving near the surface where sunlight is abundant.

Maresca believes that this surface-level presence may be tied to their ability to use sunlight. While the bacteria's photosystem does not function in the same way as typical photosynthesis, they grow faster in light than in darkness, hinting at a complex relationship with sunlight.

“Many of them have a simple photosystem that can convert light energy into chemical energy,” Maresca explained. “It’s similar to the one we have in our eyes. 

The newly developed genetic tools allow researchers to manipulate the bacteria’s genes, either by inactivating or replacing them. This advancement enables scientists to study how specific genes influence the bacteria’s adaptation to different environments and interactions with other microorganisms.

Maresca’s team is also investigating whether these bacteria have a circadian rhythm, similar to the day-night cycle seen in animals. The bacteria possess a gene called cryptochrome, which regulates circadian rhythms in other organisms. Current experiments aim to determine what happens if this gene is removed.

Actinobacteria play a crucial role in the carbon cycle of freshwater ecosystems by processing organic carbon produced by algae. This relationship makes them vital to the health and balance of these environments.

The genetic tools now allow researchers to study these bacteria directly, rather than relying on expressing their genes in model organisms like E. coli, which do not fully replicate the functions of actinobacteria.