The increasing consumption of metals and declining ore grades necessitate efficient metal production to reduce pressure on resources and minimize environmental risks. This thesis investigates microbiological reduction of elemental sulfur under high temperature and low pH conditions for metal recovery. Using industrial sludge as inoculum, a gas-lift reactor achieved sulfide production rates of 80 mg·L-1·d-1 S2- at pH 3.5 and 80°C. A continuous-feed gas-lift reactor demonstrated that operational parameters did not limit sulfidogenic activity, and decreasing temperature to 60°C increased the VSPR by 3.2-fold. Under metal stress, microbial sulfidogenesis increased, with correlations between redox conditions and stimulation of sulfidogenic activity. Mesophilic conditions yielded higher VSPR than thermophilic conditions, but VSPR decreased at acidic pH levels. Desulfurella was the sole sulfur reducer in acidophilic conditions. The research presents potential applications for hydrometallurgical processes and highlights opportunities for further investigation.