Raina Margaret Maier

Raina Margaret Maier

Professor, Environmental Science
Professor, Pharmaceutical Sciences
Professor, Pharmacology and Toxicology
Professor, BIO5 Institute
Primary Department
Department Affiliations
Contact
(520) 621-7231

Research Interest

Raina M Maier, PhD, is a Professor of Environmental Microbiology in the Department of Soil, Water and Environmental Science and Director of the University of Arizona NIEHS Superfund Research Program. She also serves as Director of the University of Arizona Center for Environmentally Sustainable Mining and as Deputy Director of the TRIF Water Sustainability Program. Dr. Maier is internationally known for her work on microbial surfactants (biosurfactants) including discovery of a new class of biosurfactants and of novel applications for these unique materials in remediation and green technologies. She is also recognized for her work on the relationships between microbial diversity and ecosystem function in oligotrophic environments such as carbonate caves, the Atacama desert, and mine tailings. Dr. Maier has published over 100 original research papers, authored 23 book chapters, and holds a patent on the use of biosurfactants to control zoosporic plant pathogens. She is the lead author on the textbook “Environmental Microbiology” currently in its second edition.Dr. Maier emphasizes a multidisciplinary approach to her work and has served as PI or co-PI on several large granting efforts including the UA NIEHS Superfund Research Program, the UA NSF Kartchner Caverns Microbial Observatory, and the UA NSF Collaborative Research in Chemistry grant on biosurfactants.

Publications

Miller, R. M., Park, E., & Thomas, J. A. (1991). Reduction (dethiolation) of protein mixed-disulfides; distribution and specificity of dethiolating enzymes and N,N′-bis(2-chloroethyl)-N-nitrosourea inhibition of an NADPH-dependent cardiac dethiolase. Archives of Biochemistry and Biophysics, 287(1), 112-120.

PMID: 1897987;Abstract:

The S-thiolated proteins phosphorylase b (Phb) and carbonic anhydrase III (CAIII) were prepared with [3H]glutathione in a reaction initiated with diamide. These substrates were used to measure the rate of reduction (dethiolation) of protein mixed-disulfides by enzymes with properties similar to those of thioredoxin and glutaredoxin. This enzyme activity is termed a dethiolase since the identities of the enzymes are still unknown. The dethiolation of either S-[3H]glutathiolated Phb or S-[3 H]glutathiolated CAIII was employed in tissue assays and for study of two partially purified dethiolases from cardiac tissue. NADPH-dependent dethiolase activity was most abundant except in rat liver and muscle. Total dethiolase activity was approximately 10-fold higher in neutrophils, 3T3-L1 cells, and Escherichia coli than in other sources. Rat skeletal muscle had 3- to 4-fold higher dethiolase activity than rat heart or liver. These data indicate that protein dethiolase activity is ubiquitous and that normal expression of the two dethiolase activities varies considerably. A partially purified cardiac NADPH-dependent dethiolase acted on Phb approximately 1.5 times faster than CAIII, and a glutathione (GSH)-dependent dethiolase acted on Phb 3 times faster than CAIII. The Km for glutathione for the GSH-dependent dethiolase was 15 μm with Phb as substrate and 10 μm with CAIII. Thus, the GSH-dependent dethiolase is probably not affected by normal changes in the cardiac glutathione content (normally approximately 3 mm). Partially purified cardiac NADPH-dependent dethiolase was inactivated by BCNU (N,N′-bis(2-chloroethyl)-N-nitrosourea) and the GSH-dependent dethiolase was unaffected under similar conditions. In a soluble extract from bovine heart, 200 μm BCNU inhibited NADPH-dependent dethiolase by more than 60% but did not affect GSH-dependent activity. These results demonstrate that BCNU is a selective inhibitor of the NADPH-dependent dethiolase. © 1991.

Neilson, J. W., Jordan, F. L., & Maier, R. M. (2013). Analysis of artifacts limiting the use of DGGE for quantitative diversity analysis. J Microbial Methods, 92, 256-263.
Sandrin, T. R., Herman, D. C., & Maier, R. M. (2009). Physiological Methods. Environmental Microbiology, 191-223.
Bodour, A. A., & Miller-Maier, R. M. (1998). Application of a modified drop-collapse technique for surfactant quantitation and screening of biosurfactant-producing microorganisms. Journal of Microbiological Methods, 32(3), 273-280.

Abstract:

A drop-collapse method has been refined for use as both a qualitative assay to screen for surfactant-producing microbes, and as a quantitative assay to determine surfactant concentration. The assay is rapid, easy to perform, reproducible and requires little specialized equipment. The assay is performed in a 96-microwell plate, where each well is thinly coated with oil. A 5 μL sample droplet is added to the center of a well and observed after 1 min. The droplet will either bead up, spread out slightly or collapse, depending on the amount of surfactant in the sample. The basis for this method is the type of oil used to coat each well. In the qualitative method, each well is coated with 1.8 μL of Pennzoil® and either the drop collapses, indicating the presence of surfactant (a positive result), or the drop remains beaded, indicating the absence of surfactant (a negative response). In the quantitative method, each well is coated with 2 μL of mineral oil, and a dissecting microscope is used to measure the diameter of the droplet at 1 min. Results with both a test biosurfactant (rhamnolipid) and a test synthetic surfactant (sodium dodecyl sulfate) indicate a direct linear correlation between droplet diameter and surfactant concentration. The drop-collapse method has several advantages over commonly used methods that measure surface tension, such as the du Nouy ring method; a smaller volume is required (5 μL vs. 20 mL), the effective range of measurement is greater and it does not require specialized equipment. Copyright (C) 1998 Elsevier Science B.V.

Al-Tahhan, R., Sandrin, T. R., Bodour, A. A., & Maier, R. M. (2000). Rhamnolipid-induced removal of lipopolysaccharide from Pseudomonas aeruginosa: Effect on cell surface properties and interaction with hydrophobic substrates. Applied and Environmental Microbiology, 66(8), 3262-3268.

PMID: 10919779;PMCID: PMC92143;Abstract:

Little is known about the interaction of biosurfactants with bacterial cells. Recent work in the area of biodegradation suggests that there are two mechanisms by which biosurfactants enhance the biodegradation of slightly soluble organic compounds. First, biosurfactants can solubilize hydrophobic compounds within micelle structures, effectively increasing the apparent aqueous solubility of the organic compound and its availability for uptake by a cell. Second, biosurfactants can cause the cell surface to become more hydrophobic, thereby increasing the association of the cell with the slightly soluble substrate. Since the second mechanism requires very low levels of added biosurfactant, it is the more intriguing of the two mechanisms from the perspective of enhancing the biodegradation process. This is because, in practical terms, addition of low levels of biosurfactants will be more cost-effective for bioremediation. To successfully optimize the use of biosurfacrants in the bioremediation process, their effect on cell surfaces must be understood. We report here that rhamnolipid biosurfactant causes the cell surface of Pseudomonas spp. to become hydrophobic through release of lipopolysaccharide (LPS). In this study, two Pseudomonas aeruginosa strains were grown on glucose and hexadecane to investigate the chemical and structural changes that occur in the presence of a rhamnolipid biosurfactant. Results showed that rhamnolipids caused an overall loss in cellular fatty acid content. Loss of fatty acids was due to release of LPS from the outer membrane, as demonstrated by 2-keto-3-deoxyoctonic acid and sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis and further confirmed by scanning electron microscopy. The amount of LPS loss was found to be dependent on rhamnolipid concentration, but significant loss occurred even at concentrations less than the critical micelle concentration. We conclude that rhamnolipid-induced LPS release is the probable mechanism of enhanced cell surface hydrophobicity.