Heavy Metal Resistance Strategies of Acidophilic Bacteria and Their Acquisition: Importance for Biomining and Bioremediation

Microbial solubilizing of metals in acid environments is successfully used in industrial bioleaching of ores or biomining to extract metals such as copper, gold, uranium and others. This is done mainly by acidophilic and other microorganisms that mobilize metals and generate acid mine drainage or AMD, causing serious environmental problems. However, bioremediation or removal of the toxic metals from contaminated soils can be achieved by using the specific properties of the acidophilic microorganisms interacting with these elements. These bacteria resist high levels of metals by using a few "canonical" systems such as active efflux or trapping of the metal ions by metal chaperones. Nonetheless, gene duplications, the presence of genomic islands, the existence of additional mechanisms such as passive instruments for pH and cation homeostasis in acidophiles and an inorganic polyphosphate-driven metal resistance mechanism have also been proposed. Horizontal gene transfer in environmental microorganisms present in natural ecosystems is considered to be an important mechanism in their adaptive evolution. This process is carried out by different mobile genetic elements, including genomic islands (GI), which increase the adaptability and versatility of the microorganism. This mini-review also describes the possible role of GIs in metal resistance of some environmental microorganisms of importance in biomining and bioremediation of metal polluted environments such as Thiomonas arsenitoxydans, a moderate acidophilic microorganism, Acidithiobacillus caldus and Acidithiobacillus ferrooxidans strains ATCC 23270 and ATCC 53993, all extreme acidophiles able to tolerate exceptionally high levels of heavy metals. Some of these bacteria contain variable numbers of GIs, most of which code for high numbers of genes related to metal resistance. In some cases there is an apparent correlation between the number of metal resistance genes and the metal tolerance of each of these microorganisms. It is expected that a detailed knowledge of the mechanisms that these environmental microorganisms use to adapt to their harsh niche will help to improve biomining and metal bioremediation in industrial processes.

Cirugía endoscópica por monopuerto: reporte de nuestra experiencia en los primeros 175 casos por sils port en Venezuela / Endoscopic surgery by singleport: report of our experience in the first 175 cases by sils port in Venezuela

El último paso hacia el menor grado de invasión después del surgimiento de la cirugía laparoscópica ocurre cuando los cirujanos del mundo se inician en técnicas emergentes, que entre otras, utilizan el ombligo como único puerto de entrada al abdomen quedando camufladas en la cicatriz umbilical, Presentamos la experiencia inicial de nuestro grupo, entre julio de 2009 hasta enero 2011 en variados procedimientos laparoscópicos por monopuerto con el uso del dispositivo SILS® port. Fueron intervenidos 175 pacientes, 163 adultos (93%), 12 niños (7%), todos abordados por un sólo puerto y a través del SILS® port. Se realizaron 102 colecistectomías (58%), 37 apendicectomías (21%), 8 histerectomías (4,6%), 7 ooforectomías (4%), 7 biopsias hepáticas (4%), 6 liberación de bridas y adherencias (3,4%), 4 salpingoclasias (2,3%), 2 esplenectomías (1%), 1 miotomía de Heller con funduplicatura de Dor (0,6%) 1 hiatoplasia esofágica (0.6%). Los procedimientos complejos se efectuaron después de realizados los primeros 50 casos. Todos los procedimientos en niños se completaron por incisión única de manera satisfactoria. En los adultos, 6 requirieron un puerto un adicional, en un paciente fue necesario dos puertos con posterior conversión a laparotomía (hiatoplastia esofágica). Los tiempos promedios resultaron para colecistectomías 42 min (12-72 min), apendicectomía 37,5 min (13-62 min), histerectomías 95 min (65-125 min), ooforectomías 32,5 min (15-50 min), salpingoclasia 18,5 min (12-25 min), miotomía de Heller 182 min, hiatoplastia esofágica 155 min. La cirugía laparoscópica por incisión única es una técnica emergente en franco desarrollo, en niños ha demostrado ser un procedimiento seguro y eficaz, al igual que en adultos. El desarrollo y perfeccionamiento del instrumento hará ampliar el horizonte y abarcar cirugía más complejas y considerarse como alternativa a la cirugía laparoscópica tradicional otorgando el beneficio de menos dolor y mejores resultados estéticos...

We present the initial experience of our work group, between July 2009 and January 2011 in several laparoscopic procedures by monoport with device SILS port. Patients and method: 175 patients underwent surgery, 163 adults (93%), 12 children (7%), all boarded through a single port with SILS port device, 102 cholecystectomies were made (58%), 37 appendectomies (21%) 8 hysterectomies (4.6%), 7 oophorectomies (4%). 7 hepatic biopsies (4%), 6 liberation of bridles and adhesions (3,4%), 4 segmental resection of fallopian tube (2.3%), 2 splenectomies (1%), 1 Heller miotomy with Dor funduplication (0.6%) and 1 hiatal repair (0.6%). The complex procedures were carried out alter made the first 50 cases. All the procedures in children were completed through unique incision. In the adults. 6 required an additional port; in a patient was necessary two port with later conversion to laparotomy (hiatal hernia repair). The operative times averages were for cholecystectomies 42 min (12-72 min), Appendectomies 37,5 min. (13-62 min). Hysterectomies 95 min (65-125 min), Oophorectomies 32.5 min (15-50 min), segmental resection of fallopian tube 18.5 min (12-25 min), Heller miotomy 182 min. Hiatal hernia repair 155 min. The laparoscopic surgery through unique incision is an emergent technique in frank development, in children has demonstrated to be a safe and effective procedure, like in adults. The development and improvement of instruments will make extend the horizon and include more complex surgeries and consider themselves like alternative to the traditional laparoscopic surgery, granting the benefit of less pain and better aesthetic results. The development of skills and abilities to move in a NEW ATMOSPHERE represent a main concern.

Geobacillus stearothermophilus LV cadA gene mediates resistance to cadmium, lead and zinc in zntA mutants of Salmonella entérica serovar Typhimurium

Salmonella entérica serovar Typhimurium cells expressing the cadA gene of Geobacillus stearothermophilus LV exhibit a hypersensitive phenotype to cadmium chloride. Deletion of the ORF STM3576 from the Salmonella genome resulted in cadmium, lead and zinc sensitivity, confirming that this ORF is a homologue of the zntA gene. The observed sensitivity was reverted upon expression of the G. stearothermophilus LV cadA gene. These results indicate that the cadA gene product is involved in Cd, Pb and Zn resistance as a classical P-type ATPase and strongly suggest that the observed hypersensitive phenotype to these metals can be related to the function of the host ·zntA gene product.

The acetyl xylan esterase II gene from Penicillium purpurogenum is differentially expressed in several carbon sources, and tightly regulated by pH

The expression of the acetyl xylan esterase II (axeII) gene from Penicillium purpurogenum is repressed by glucose and induced by xylan, as well as to a small degree by xylose and xylitol. This gene is expressed at neutral pH, but not under alkaline or acidic conditions, in agreement with previous findings for other xylanolytic genes of this organism. This is the first report showing pH regulation of an axe gene.