Cometabolic Biodegradation of Hydrazine by Chlorella vulgaris-Bacillus Extremophilic Consortia: Synergistic Potential for Space and Industry.

Hydrazine, a highly toxic and reactive compound widely used as rocket fuel, poses significant environmental and health risks, particularly in long-term space missions. This study investigates the cometabolic capacity of Chlorella vulgaris and seven extremophilic Bacillus spp. strains-isolated from the arid Dead Sea region-to tolerate and degrade hydrazine at concentrations up to 25 ppm. The microalga C. vulgaris reduced hydrazine levels by 81% within 24 h at 20 ppm, while the Bacillus isolates achieved an average reduction of 45% over 120 h. Identified strains included B. licheniformis, B. cereus, and B. atrophaeus. Co-culture experiments demonstrated that C. vulgaris and B. cereus (isolate ISO-36) stably coexisted without antagonistic effects, suggesting a synergistic detoxification interaction. Flow cytometry revealed that most bacteria transitioned into spores under stress, highlighting a survival adaptation. Titanium, representing a biocompatible material common in aerospace hardware, did not inhibit microbial growth or hydrazine degradation. These findings underscore the potential of Dead Sea-derived microbial consortia for cometabolic hydrazine detoxification and support the feasibility of converting spacecraft components into functional photobioreactors. This approach offers dual-use benefits for space missions and industrial wastewater treatment. Future studies should investigate degradation pathways, stress resilience, and bioreactor scale-up.