Microorganisms with importance to mineral biotechnology are commonly maintained through live culture
maintenance, which can be labour intensive and expensive. Live culture maintenance can also result
in contamination, genetic drift and loss of traits, or whole strains, that are crucial to some biotechnological
applications. This study aimed to investigate alternative preservation methods, and to determine the
best method required for the preservation of mixed microbial cultures capable of bioleaching chalcopyrite
under salt stress. Live culture maintenance followed by cold storage at 4 C, liquid drying and
temperature-controlled cryopreservation were used to preserve mesophilic (30 C), moderately thermophilic
(45 C) and thermophilic (60 C) bioleaching cultures. Recovery of cells and bioleaching activity
were determined following revival. Results were compared to cultures routinely maintained by subculturing.
Across all temperatures, cryopreservation with 10% (v/v) glycerol as a cryoprotectant resulted in
the highest post-revival cell recovery. Further research is required to determine if the microbial diversity
in each culture is impacted by the preservation method employed.