Garza-Gonzalez Maria Teresa, Barboza Perez Daniel, Vazquez Rodriguez Augusto, Garcia-Gutierrez Domingo Ixcoatl, Zarate Xristo, Cantú Cardenas Maria Elena, Urraca-Botello Ludwing Ilytch, Lopez-Chuken Ulrico Javier, Trevino-Torres Alberto Ludovico, Cerino-Córdoba Felipe de Jesus, Medina-Ruiz Pavel, Villarreal-Chiu Juan Francisco, Morones-Ramirez Jose Ruben
Facultad de Ciencias Químicas, Universidad Autónoma de Nuevo León, Pedro de Alba, S/N, San Nicolás de los Garza, Nuevo León, México.
Centro de Investigacion en Biotecnologia y Nanotoxicologia, Facultad de Ciencias Quimicas, Universidad Autonoma de Nuevo Leon. Parque de Investigacion e Innovacion Tecnologica, Km. 10 autopista al Aeropuerto Internacional Mariano Escobedo, Apodaca, Nuevo Leon, 66629 Mexico.
PLoS One. 2016 Feb 1;11(2):e0148430. doi: 10.1371/journal.pone.0148430. eCollection 2016.
There is a current need to develop low-cost strategies to degrade and eliminate industrially used colorants discharged into the environment. Colorants discharged into natural water streams pose various threats, including: toxicity, degradation of aesthetics and inhibiting sunlight penetration into aquatic ecosystems. Dyes and colorants usually have complex aromatic molecular structures, which make them very stable and difficult to degrade and eliminate by conventional water treatment systems. The results in this work demonstrated that heavy metal-resistant Rhodotorula mucilaginosa strain UANL-001L isolated from the northeast region of Mexico produce an exopolysaccharide (EPS), during growth, which has colorant adsorption potential. The EPS produced was purified by precipitation and dialysis and was then physically and chemically characterized by Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy, and chemical elemental analysis. Here, the ability of the purified EPS produced to adsorb methylene blue (MB), which served as a model colorant, is studied. MB adsorption by the EPS is found to follow Langmuir Adsorption Isotherm kinetics at 25°C. Further, by calculating the Langmuir constant the adsorption capabilities of the EPS produced by the Rhodotorula mucilaginosa strain UANL-001L is compared to that of other adsorbents, both, microbially produced and from agroindustrial waste. The total adsorption capacity of the EPS, from the Rhodotorula mucilaginosa strain UANL-001L, was found to be two-fold greater than the best bioadsorbents reported in the literature. Finally, apart from determining which heavy metals stimulated EPS production in the strain, the optimal conditions of pH, heavy metal concentration, and rate of agitation of the growing culture for EPS production, was determined. The EPS reported here has the potential of aiding in the efficient removal of colorants both in water treatment plants and in situ in natural water streams.
当前需要制定低成本策略，以降解和消除排放到环境中的工业用着色剂。排放到天然水流中的着色剂会造成各种威胁，包括：毒性、美观性下降以及抑制阳光穿透水生生态系统。染料和着色剂通常具有复杂的芳香族分子结构，这使得它们非常稳定，难以通过传统的水处理系统降解和消除。这项工作的结果表明，从墨西哥东北部地区分离出的耐重金属粘红酵母菌株UANL-001L在生长过程中会产生一种胞外多糖（EPS），该多糖具有吸附着色剂的潜力。所产生的EPS通过沉淀和透析进行纯化，然后通过扫描电子显微镜、傅里叶变换红外光谱和化学元素分析对其进行物理和化学表征。在此，研究了纯化后的EPS对作为模型着色剂的亚甲基蓝（MB）的吸附能力。发现EPS对MB的吸附在25°C下遵循朗缪尔吸附等温线动力学。此外，通过计算朗缪尔常数，将粘红酵母菌株UANL-001L产生的EPS的吸附能力与其他吸附剂（包括微生物产生的吸附剂和农业工业废料中的吸附剂）进行了比较。发现粘红酵母菌株UANL-001L产生的EPS的总吸附容量比文献中报道的最佳生物吸附剂高出两倍。最后，除了确定哪些重金属刺激了该菌株中EPS的产生外，还确定了EPS产生过程中生长培养物的最佳pH值、重金属浓度和搅拌速率条件。本文报道的EPS有潜力在水处理厂和天然水流原位有效去除着色剂方面发挥作用。
