Blue Point Eecr1b -

Strain EECR1B, colloquially named "Blue Point" due to its distinctive cobalt-blue pigmentation under anaerobic electron-donating conditions, was isolated from a hydrothermal vent in the Pacific’s Pescadero Basin . This paper reports on its extraordinary dual capability: (1) direct extracellular electron transfer (EET) to solid-state electrodes at rates exceeding known Geobacter species, and (2) a novel, cryptic sulfur reduction pathway that operates only under high hydrostatic pressure. EECR1B challenges the current dichotomy between electrogenic bacteria and chemolithotrophic archaea, offering a new chassis for bioelectrochemical systems in extreme environments.

Electroarchaea, Blue Pigmentation, Cryptic Sulfur Cycle, Hadal Biosphere, Bioelectrochemical Pulse Effect. blue point eecr1b

Most archaea from hydrothermal vents appear cream, white, or faint pink. EECR1B, however, exhibits a deep Prussian blue hue when grown in a three-electrode bioreactor poised at -0.25 V (vs. Ag/AgCl). Spectrophotometry and X-ray fluorescence (XRF) revealed that the pigmentation is not due to a carotenoid, but to a cytoplasmic accumulation of reduced iron-sulfur clusters (Fe₄S₄)²⁺—a direct result of hyperactive electron uptake. The "Point" refers to the sharp, needle-like biofilm structures it forms on cathode surfaces, maximizing surface area. Strain EECR1B, colloquially named "Blue Point" due to

Authors: A. Marin, K. Deep-Sea & J. Vent Affiliation: Institute of Extreme Biogeochemistry, Hadal Observatory Ag/AgCl)