Asian Journal of Tropical Biotechnology

Hexavalent chromium [Cr(VI)] tolerance and reduction activity of Synechococcus sp. and Synechocystis sp. isolated in West and South Bay of Laguna de Bay, Philippines

2024-03-22T11:49:51+00:00

Abstract. Pujalte ECO, Posadas KDB, Morales TC, Chang ACG. 2024. Hexavalent chromium [Cr(VI)] tolerance and reduction activity of Synechococcus sp. and Synechocystis sp. isolated in West and South Bay of Laguna de Bay, Philippines. Asian J Trop Biotechnol 21: 1-9. Cyanobacteria are prevalent in terrestrial and aquatic ecosystems which can tolerate stress caused by heavy metals. In the Philippines, various anthropogenic activities have contributed to the heavy metal contamination in water systems. Laguna de Bay is the largest inland body of water in the Philippines that functions as a multipurpose lake; however, heavy metal contamination such as hexavalent chromium [Cr(VI)] has progressed through the years due to various anthropogenic activities. This study evaluated the capability of cyanobacterial strains isolated from Laguna de Bay to tolerate and reduce varying concentrations of Cr(VI) using different parameters. Cyanobacterial isolates from Tadlac and Jamboree Lake were subjected to tolerance assay in varying Cr(VI) concentrations, followed by the reduction assay utilizing 1,5-Diphenylcarbazide (1,5-DPCZ) at OD₅₄₀. Through morphological characterization, two genera were identified: Synechococcus sp. from West Bay and Synechocystis sp. from South Bay. This study revealed that both isolates could tolerate and reduce high Cr(VI) levels within optimum pH of 7 and 8, respectively. The data acquired from the tolerance assay showed that a Cr(VI) concentration of 1000 mg/L still permitted the growth of the two cyanobacteria genera. Percentage reduction of the isolates at their respective optimal pH showed variation wherein Synechococcus sp. at pH 7 exhibited a 58% Cr(VI) average reduction compared to Synechocystis sp. at pH 8, which then exhibited a 66% Cr(VI) average reduction. The present study's findings indicate the potential of the two indigenous cyanobacteria in the bioremediation of Cr(VI) in Laguna de Bay.

Review: Current perspectives on enzyme applications in medicine, agriculture, and industries

2024-05-03T00:07:44+00:00

Abstract. Dahiru MM, Abdulhamid AA, Abaka AM. 2024. Review: Current perspectives in enzyme applications in medicine, agriculture, and industries. Asian J Trop Biotechnol 21: 10-25. The conventional use of chemicals worldwide in different industries has significantly increased, impacting the environment. The need to improve industrial processes led to prospects into enzymes from various sources, including microbial sources to substitute the toxic chemicals and processes with environmentally friendly processes and biodegradable waste products. Enzyme applications are notably getting more attention in medicine, agriculture, and industries, including pharmaceuticals, food, detergents, leather, and cosmetics. They are utilized in these industries to enhance durability of product, shorten process time, improve efficiency and stability, and properly manage waste. Medicine mainly uses them for diagnostic and treatment purposes, including proteases and amylases. The pharmaceutical industries explore the specificity of enzymes to bind target substrates, yielding specific and desired products via reactions, including hydrolysis, acylation, and esterifications. Waste and pathogen treatments, in addition to soil and plant improvements, are the major applications of enzymes in agriculture, employing pectinases, cellulases, and xylanases. In the food industry, amylases are used for starch degradation and dough improvement, while proteases are used for juice beer production clearance. The detergent industry adds enzymes to its formulations, including lipases, proteases, and cellulases, to improve stain removal by modifying fabric fibers to release dirt and soil particles. Enzymes, including proteases and lipases, are used in the leather industry for curing, soaking, dehairing, degreasing, and tanning, in addition to waste elimination. In comparison, an immobilized lipase is utilized in the cosmetic industry to produce retinoids, protein disulfide isomerase, glutathione sulfhydryl oxidase, and transglutaminase are applied in hair waving. Furthermore, developing the cost-effective technique of enzyme immobilization technology further promotes the application of enzymes in these endeavors attributed to their stability and recyclability. Thus, there is a significant improvement in research towards green and eco-friendly applications of enzymes. This review discusses how enzymes have been successfully deployed and utilized in medicine, agriculture, pharmaceutical, food, detergent, leather, and cosmetics industries. Enzymes in these industries exhibited beneficial applications, though the recyclability of the enzymes remains challenging for some endeavors. However, immobilization techniques have been gaining attention which might present a solution to the challenges associated with enzyme reusability.

Isolation, identification, and characterization of heavy metal-resistant bacteria from soil samples collected at a cement company in Nigeria

2024-05-04T22:18:10+00:00

Abstract. Martins AL, Silas TV, Abah MA, Adebisi AK, Sunday AM, Emochonne RY, Iheanacho CC. 2024. Isolation, identification, and characterization of heavy metal-resistant bacteria from soil samples collected at a cement company in Nigeria. Asian J Trop Biotechnol 21: 26-32. Many heavy metals, including cadmium, chromium, copper, lead, and zinc, are produced during cement-making. Even in low quantities, most of the heavy metals released are known to be harmful to plants and animals. The objective of this study was to isolate, identify and characterize heavy metal-resistant bacteria from soil samples collected at Benue Cement Company, Nigeria. Soil samples taken near the Gboko facility of Nigerian cement manufacturer Benue Cement Plc were tested for heavy metal-resistant bacteria. Results from the study revealed that compared to other metals (Pb, Cr, and Cd), the concentration of copper and zinc was consistently quite high across all sites. The levels of all components examined were determined to be higher than the limits allowed by the World Health Organization In this study, Cd, Zn, Cr, Cu, and Pb were found in soil samples taken from the Benue cement industry, according to the analysis of heavy metals. The results obtained from this study further revealed that out of 20 isolates only five (5) bacterial isolates, namely Staphylococcus aureus, Escherichia coli, Proteus sp., Bacillus cereus, and Lactobacillus which showed high levels of heavy metal resistance were selected for further studies in secondary screening. Based on the biochemical tests, S. aureus reacted positively to catalase and coagulase test. They were also seen to ferment lactose, sucrose and glucose. The E. coli reacted negatively to citrate, catalase, coagulase tests, and did not ferment sucrose. However, the bacteria fermented lactose and glucose. Lactobacillus reacted positively to only citrate but fermented the three sugars. Proteus sp. fermented glucose and sucrose and also reacted positively to citrate, catalase and urea tests. The B. cereus fermented glucose and sucrose. The bacteria also reacted positively to only citrate and catalase tests. Results of showed that S. aureus had MIC values between 12 and 16 mg/L, E. coli between 20 and 50 mg/L, Proteus species between 15 and 64 mg/L, and B. cereus between 10 and 18 mg/L, all against various metals. The B. cereus showed the lowest resistance to several heavy metals, while E. coli showed the highest resistance. Additionally, E. coli demonstrated a significant resistance level to all ten antibiotics examined. Antibiotic resistance was highest in E. coli and lowest in Proteus species. The findings of this study revealed that the four isolates that showed high tolerance to heavy metals could be used as inoculants to bioremediate cement sites that polluted by heavy metals.