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.

Cyanide (CN) is a toxic environmental pollutant generated by various industrial activities, necessitating the application of bioremediation techniques for its degradation. Biodegradation is a more cost-effective and environmentally friendly technique with high efficiency in CN removal. This study isolated cyanide-degrading bacteria from Tutupaca mining site soil from Tacna, Peru. Bacillus subtilis strain TT10s was selected for its exceptional capacity to rapidly and completely eliminate cyanide under alkaline conditions (pH 10.5), removing 1000 ppm cyanide within 48 h. A kinetic analysis revealed that the biodegradation follows second-order rate kinetics (k₂ = 0.08649 mg/(mg·h), R² = 0.96622), consistent with the literature attribution of the rate-limiting step to the inducible cyanide dihydratase enzyme, which converts cyanide into ammonia and formate via the Michaelis–Menten model. Fourier-transform infrared spectroscopy (FTIR) spectral analysis further corroborated this enzymatic mechanism, showing the disappearance of CN peaks coupled with the emergence of ammonia (NH) and formate (C=O) peaks. Quantitative kinetic modelling integrated with FTIR profiles and degradation curves implicates cyanide dihydratase as the key rate-controlling enzyme in alkaline cyanide biodegradation without the need for an extra carbon source, generating interest for future bioremediation applications in highly contaminated environments.

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.

Mining environmental liabilities (MELs) are abandoned deposits resulting from extractive activities that pose a high risk of contamination and remain an unresolved challenge for authorities worldwide. This study evaluated the contamination levels of potentially toxic elements (PTEs) and their associated ecological risks in MELs, using multiple environmental indices. Analyses were performed following the EPA 6020A method with acid digestion and inductively coupled plasma mass spectrometry (ICP-MS), while free cyanide and hexavalent chromium were determined using the EPA 9013A and EPA 7199 methods, respectively. The results revealed elevated concentrations of arsenic (1,102 mg/kg), cadmium (271 mg/kg), lead (15,961 mg/kg), and free cyanide (64 mg/kg), which exceeded regulatory standards by a considerable margin. Statistically significant differences were observed across the sites (p < 0.05). In addition, the presence of flora, fauna, rivers, and rural communities in proximity to these abandoned mining sites amplifies both ecological and social risks. The applied indices consistently indicated severe levels of contamination and high ecological risk across all areas evaluated. Although no statistically significant differences were found in some indices (p > 0.05), the magnitude of the recorded values remains ecologically relevant. Notably, each index has its own interpretative scale, allowing for an independent and robust evaluation of contamination severity and its potential ecological implications. Principal Component Analysis (PCA) revealed multiple sources of pollution, while Spearman correlation analysis identified strong associations among PTEs, suggesting common environmental dispersion pathways. This research provides a critical preliminary assessment of the risks associated with these environmental legacies and emphasizes the urgent need for remediation efforts at both local and global scales. The current lack of action is largely attributed to the absence of comprehensive baseline assessments. The findings underscore the importance of prioritizing their management through sustainable strategies and international policies to mitigate environmental impacts.

Olive, Olea europaea L. (Oleaceae), cultivation is affected by significant yield losses caused by Palpita persimilis Munroe (Lepidoptera: Crambidae), a defoliating pest in South America. Its control currently relies on synthetic pesticides, which have adverse environmental effects. This study investigated native entomopathogenic bacteria isolated from the rhizosphere of olive trees in Tacna, Peru. A total of 36 bacterial isolates were obtained, of which six strains showing more than 70% larval mortality were selected for further evaluation. Morphological and molecular analyses suggested a tentative affiliation of the isolates with bacterial groups related to the genera Lysinibacillus, Paenibacillus, Priestia, and Bacillus. Bioassays demonstrated that larval mortality depended on the bacterial concentration and exposure time. Strains such as Peribacillus sp. UNM achieved 100% larval mortality after 96 h at a concentration of 1 × 10⁹ CFU mL⁻¹. Analysis using a generalized linear model (GLM) with a binomial distribution confirmed that bacterial strain, concentration, and exposure time significantly influenced larval mortality, indicating that mortality responses varied according to bacterial concentration and exposure time. These findings provide preliminary laboratory evidence of entomopathogenic activity associated with native bacterial isolates against P. persimilis and support future investigations aimed at evaluating these isolates under field conditions in olive agroecosystems.

El presente texto universitario se propone como un apoyo para el docente y los estudiantes, que les permitirá desarrollar actividades prácticas en el campo de la biología molecular y a su vez incentivarlos a desarrollar investigación científica, explorando y evaluando técnicas básicas a nivel molecular. El Capítulo 1 se enfoca en los aspectos generales básicos y en los antecedentes históricos de la biología molecular, esta ciencia a través del tiempo ha generado mucho interés en los investigadores, que gracias a los avances científicos en técnicas y en el desarrollo tecnológico ha permitido mejorar los equipos que son de utilidad para ser explorar este campo, a un nivel molecular. En el Capítulo 2 se desarrolla algunas técnicas básicas de biología molecular y secuenciación, por lo que ayudará a comprender de manera fácil y detallada los métodos y/o técnicas de esta rama de la Biología, hasta la secuenciación del material genético. Por ello, el lector será capaz de conocer las técnicas en biología molecular, debido a que en los últimos años ha aumentado el uso de esta tecnología en los diferentes campos de investigación como la biotecnología, agroindustria, medicina, farmacología, microbiología entre otros. Es así, que se pretende contribuir en la producción del conocimiento y dar un enfoque amplio de las metodologías a utilizar para mejorar un determinado proceso, por lo que se precisa ampliar la conceptualización de la relación teoría-práctica, que requiere planificarse e incentivar la investigación en los alumnos.