Phenol degradation and heavy metal tolerance of Antarctic yeasts.

In cold environments, biodegradation of organic pollutants and heavy metal bio-conversion requires the activity of cold-adapted or cold-tolerant microorganisms. In this work, the ability to utilize phenol, methanol and n-hexadecane as C source, the tolerance to different heavy metals and growth from 5 to 30 °C were evaluated in cold-adapted yeasts isolated from Antarctica. Fifty-nine percent of the yeasts were classified as psychrotolerant as they could grow in all the range of temperature tested, while the other 41% were classified as psychrophilic as they only grew below 25 °C. In the assimilation tests, 32, 78, and 13% of the yeasts could utilize phenol, n-hexadecane, and methanol as C source, respectively, but only 6% could assimilate the three C sources evaluated. In relation to heavy metals ions, 55, 68, and 80% were tolerant to 1 mM of Cr(VI), Cd(II), and Cu(II), respectively. Approximately a half of the isolates tolerated all of them. Most of the selected yeasts belong to genera previously reported as common for Antarctic soils, but several other genera were also isolated, which contribute to the knowledge of this cold environment mycodiversity. The tolerance to heavy metals of the phenol-degrading cold-adapted yeasts illustrated that the strains could be valuable as inoculant for cold wastewater treatment in extremely cold environments.

Bioprospection of cold-adapted yeasts with biotechnological potential from Antarctica.

The aim of this study was to investigate the ability to produce extracellular hydrolytic enzymes at low temperature of yeasts isolated from 25 de Mayo island, Antarctica, and to identify those exhibiting one or more of the evaluated enzymatic activities. A total of 105 yeast isolates were obtained from different samples and 66 were identified. They belonged to 12 basidiomycetous and four ascomycetous genera. Most of the isolates were ascribed to the genera Cryptococcus, Mrakia, Cystobasidium, Rhodotorula, Gueomyces, Phenoliferia, Leucosporidium, and Pichia. Results from enzymes production at low temperatures revealed that the Antarctic environment contains metabolically diverse cultivable yeasts, which represent potential tools for biotechnological applications. While most the isolates proved to produce 2-4 of the investigated exoenzymes, two of them evidenced the six evaluated enzymatic activities: Pichia caribbica and Guehomyces pullulans, which were characterized as psycrotolerant and psycrophilic, respectively. In addition, P. caribbica could assimilate several n-alkanes and diesel fuel. The enzyme production profile and hydrocarbons assimilation capacity, combined with its high level of biomass production and the extended exponential growth phase make P. caribbica a promising tool for cold environments biotechnological purposes in the field of cold-enzymes production and oil spills bioremediation as well.

Optimization of Culture Conditions for Growth Associated with Cr(VI) Removal by Wickerhamomyces anomalus M10.

Chromate-resistant microorganisms with the ability of reducing toxic Cr(VI) to less toxic Cr(III), are candidates for bioremediation. An alternative culture medium to reduce Cr(VI) using Wickerhamomyces anomalus M10 was optimized. Using the Plackett-Burman design, it was determined that sucrose, K2HPO4 and inoculum size had significant effects on chromate removal (i.e., reduction) at 24 h. Concentrations of these significant factors were adjusted using a complete factorial design. In this case, only the K2HPO4 effect was significant at 12 h of culture, with greater Cr(VI) removal at low concentration (1.2 g L-1). The optimum medium was validated at the fermenter scale level. Optimal culture conditions for complete removal of Cr(VI) (1 mM) were 400 rpm agitation and air flow of 1 vvm. Moreover, W. anomalus M10 completely removed consecutively added pulses of Cr(VI) (1 mM). These results show interesting characteristics from the standpoint of biotechnology because the development of a future remediation process using W. anomalus M10 can represent an efficient and highly profitable technology for removing the toxic form of Cr.

IgG4-related disease associated with immune thrombocytopenia: A clinical case report

Autoimmune pancreatitis is a characteristic manifestation of the spectrum of the disease related to IgG4, a rare autoimmune disorder that presents clinically with obstructive jaundice due to the infiltration of plasma cells and fibrosis in the pancreas. There may be other symptoms in case of involvement of other organs, and in very rare cases there is hematological involvement. We present the case of an adult man with signs of cholestasis secondary to type I autoimmune pancreatitis, with involvement of other organs and associated with thrombocytopenia that improved with systemic corticosteroid-based immunosuppressive treatment, after which the patient showed favorable clinical and analytical evolution over time.

La pancreatitis autoimmune es una manifestación característica del espectro de la enfermedad relacionada con IgG4, trastorno raro de tipo autoinmune que se presenta clínicamente con ictericia obstructiva debido a la infiltración de células plasmáticas y fibrosis en el páncreas; puede presentarse con otra sintomatología en caso de afectación de otros órganos y en muy raras ocasiones hay compromiso hematológico. Se presenta el caso de un hombre adulto con signos de colestasis secundaria a una pancreatitis autoinmune tipo i, con compromiso de otros órganos y asociada con trombocitopenia que mejoró con el tratamiento inmunosupresor a base de corticoide sistémico, luego del cual se observó una evolución favorable en cuanto a la clínica y analítica en el transcurso del tiempo.

Synergistic roles of climate warming and human occupation in Patagonian megafaunal extinctions during the Last Deglaciation.

The causes of Late Pleistocene megafaunal extinctions (60,000 to 11,650 years ago, hereafter 60 to 11.65 ka) remain contentious, with major phases coinciding with both human arrival and climate change around the world. The Americas provide a unique opportunity to disentangle these factors as human colonization took place over a narrow time frame (~15 to 14.6 ka) but during contrasting temperature trends across each continent. Unfortunately, limited data sets in South America have so far precluded detailed comparison. We analyze genetic and radiocarbon data from 89 and 71 Patagonian megafaunal bones, respectively, more than doubling the high-quality Pleistocene megafaunal radiocarbon data sets from the region. We identify a narrow megafaunal extinction phase 12,280 ± 110 years ago, some 1 to 3 thousand years after initial human presence in the area. Although humans arrived immediately prior to a cold phase, the Antarctic Cold Reversal stadial, megafaunal extinctions did not occur until the stadial finished and the subsequent warming phase commenced some 1 to 3 thousand years later. The increased resolution provided by the Patagonian material reveals that the sequence of climate and extinction events in North and South America were temporally inverted, but in both cases, megafaunal extinctions did not occur until human presence and climate warming coincided. Overall, metapopulation processes involving subpopulation connectivity on a continental scale appear to have been critical for megafaunal species survival of both climate change and human impacts.