Lyophilization is a widely employed long-term preservation method in which the bacterial survival rate largely depends on the cryoprotectant used. Bacillus cereus strain PBC was selected for its ability to thrive in environments contaminated with arsenic, lead, and cadmium, tolerate 500 ppm of free cyanide, and the presence of genes such as ars, cad, ppa, dap, among others, associated with the bioremediation of toxic compounds and enterotoxins (nheA, nheB, nheC). Following lyophilization, the survival rates for Mannitol 2.5%, Mannitol 10%, and Glucose 1% were 98.02%, 97.12%, and 96.30%, respectively, with the rates being lower than 95% for other sugars. However, during storage, for the same sugars, the survival rates were 78.71%, 97.12%, and 99.97%, respectively. In the cake morphology, it was found that the lyophilized morphology showed no relationship with bacterial survival rate. The best cryoprotectant for the PBC strain was 1% glucose since it maintained constant and elevated bacterial growth rates during storage, ensuring that the unique characteristics of the bacterium were preserved over time. These findings hold significant implications for research as they report a new Bacillus cereus strain with the potential to be utilized in bioremediation processes.

Environmental liabilities continue to pose an unresolved concern for administrators due to their high potential for ecosystem contamination. This research focuses on assessing the content of potentially toxic elements, the degree of contamination, and potential ecological risks in abandoned mining areas that formerly exploited sulfur and copper. The results showed elevated concentrations of Arsenic (1,102 mg/Kg), Cadmium (271 mg/Kg), Lead (15,961 mg/Kg). The presence of flora, fauna activity, rivers, and rural communities near the mining sites was observed, indicating significant environmental risks. The evaluated mining environmental liabilities (MELs) lack direct responsible parties, thus requiring the Peruvian government to assume remediation responsibilities. To date, no mitigation actions have been taken, primarily due to the absence of a situational diagnosis. Concerning contamination indices, such as the Geoaccumulation Index, Contamination Degree, Pollution Load Index, Contamination Load Coefficient, and Potential Ecological Risk Index, all areas exhibited some form of contamination, indicating high environmental risks. A preliminary risk assessment associated with the presence of mining environmental liabilities has been conducted, marking this research as the first of its kind in the southern region of Peru. This assessment provides administrators with crucial information to establish priorities for implementing remediation plans aimed at reducing pollutant loads. The findings underscore the urgent need for comprehensive contamination assessments and the development of effective management practices, including the implementation of a monitoring program to safeguard soils affected by mining activities. Additionally, it is essential to design various technological strategies to restore degraded ecosystems, thereby protecting rivers, agricultural zones, and nearby rural communities.