Point Eecr1b - Blue

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

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. 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. Authors: A

Electroarchaea, Blue Pigmentation, Cryptic Sulfur Cycle, Hadal Biosphere, Bioelectrochemical Pulse Effect. and (2) a novel