Julian Rafael Dib

Isolation of Bacteria from Remote High Altitude Andean Lakes Able to Grow in the Presence of Antibiotics

High altitude Andean lakes are placed in Puna desert over 4400 above sea level. Completely isolated, they are exposed to extreme environmental factors like high levels of salinity, UV radiation and heavy metals and low concentrations of phosphorus. Nevertheless, they are the habitat of enormous populations of three flamingo species that migrate among these Lakes. Previous reports have determined that bacteria isolated from these environments present high levels of resistance to antibiotics. The aim of this work was to determine the diversity of antibiotic resistant bacteria in water from Andean Lakes and their connection with flamingo enteric biota. Bacteria from water and birds faeces from high altitude Lakes: Laguna (L.) Aparejos, L. Negra, L. Vilama and L. Azul (all are located between 4,200 and 4,600 m altitude) were isolated by plating in five different Antibiotics (ampicillin, 100 microg ml(-1); chloramphenicol, 170 microg ml(-1); colistin , 20 microg ml(-1); erythromycin, 50 microg ml(-1) and tetracycline 50 microg ml(-1)). 56 bacteria were isolated and identified by 16 S rDNA sequencing. Antibiotic resistance profiles of isolated bacteria were determined for 22 different antibiotics. All identified bacteria were able to growth in multiple ATBs. Colistin, ceftazidime, ampicillin/sulbactam, cefotaxime, cefepime, cefalotin, ampicillin and erythromycin were the most distributed resistances among the 56 tested bacteria. The current results demonstrated that antibiotic resistance was abundant and diverse in high altitude Lakes. Also the present article indicates some useful patents regarding the isolation of bacteria able to grow in the present of antibiotics.

Novel linear megaplasmid from Brevibacterium sp. isolated from extreme environment.

Brevibacterium sp. Ap13, isolated from flamingos feces in Laguna Aparejos, a high‐altitude lake located at approximately 4,200 m in the northwest of Argentina was previously found to be resistant to multiple antibiotics, and was therefore screened for plasmids that may be implicated in antibiotic resistance. Brevibacterium sp. Ap13 was found to contain two plasmids of approximately 87 and 436 kb, designated pAP13 and pAP13c, respectively. Only pAP13 was stably maintained and was extensively characterized by pulsed‐field gel electrophoresis to reveal that this plasmid is linear and likely has covalently linked terminal proteins associated with its 5′ ends. This is the first report of a linear plasmid in the genus Brevibacterium and may provide a new tool for genetic manipulation of this commercially important genus. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Structural peculiarities of linear megaplasmid, pLMA1, from Micrococcus luteus interfere with pyrosequencing reads assembly

Different strains of Micrococcus luteus, isolated from high-altitude Argentinean wetlands, were recently reported to harbour the linear plasmids pLMA1, pLMH5 and pLMV7, all of which with 5′-covalently attached terminal proteins. The link between pLMA1 and the host’s erythromycin resistance as well as further presumptive qualities prompted us to perform a detailed characterization. When the 454 technology was applied for direct sequencing of gel-purified pLMA1, assembly of the reads was impossible. However, combined Sanger/454 sequencing of cloned pLMA1 fragments, covering altogether 23 kb of the 110-kb spanning plasmid, allowed numerous sequence repeats of varying in lengths to be identified thus rendering an explanation for the above 454 assembly failure. A large number of putative transposase genes were identified as well. Furthermore, a region with five putative iteron sequences is possibly involved in pLMA1 replication.

Strategies and approaches in plasmidome studies-uncovering plasmid diversity disregarding of linear elements?

The term plasmid was originally coined for circular, extrachromosomal genetic elements. Today, plasmids are widely recognized not only as important factors facilitating genome restructuring but also as vehicles for the dissemination of beneficial characters within bacterial communities. Plasmid diversity has been uncovered by means of culture-dependent or -independent approaches, such as endogenous or exogenous plasmid isolation as well as PCR-based detection or transposon-aided capture, respectively. High-throughput-sequencing made possible to cover total plasmid populations in a given environment, i.e., the plasmidome, and allowed to address the quality and significance of self-replicating genetic elements. Since such efforts were and still are rather restricted to circular molecules, here we put equal emphasis on the linear plasmids which—despite their frequent occurrence in a large number of bacteria—are largely neglected in prevalent plasmidome conceptions.

Complete Genome Sequence of pAP13, a Large Linear Plasmid of a Brevibacterium Strain Isolated from a Saline Lake at 4,200 Meters above Sea Level in Argentina.

ABSTRACT pAP13 is an 89-kb linear plasmid hosted by Brevibacterium sp. strain Ap13, an actinobacterium isolated from the feces of a flamingo from an extremely high-altitude lake in Argentina. Because of the ecological importance of the genus Brevibacterium, the absolute lack of information concerning Brevibacterium linear plasmids, and the possible ecological significance of this unusual plasmid, pAP13 was completely sequenced, including the inversely oriented termini.

First complete sequence of a giant linear plasmid from a micrococcus strain isolated from an extremely high-altitude lake.

ABSTRACT Micrococcus sp. strain V7, an actinobacterial strain adapted to the extreme conditions of the Laguna Vilama, an extremely high-altitude (4,600 m above sea level) lake in the Argentinian Puna, was found to carry the giant linear plasmid pLMV7. We determined its sequence (92,815 bp) as a prerequisite to the investigation of its role in survival in such a harsh environment.

Complete Genome Sequence of the Linear Plasmid pJD12 Hosted by Micrococcus sp. D12, Isolated from a High-Altitude Volcanic Lake in Argentina

ABSTRACT The linear plasmid pDJ12 from Micrococcus D12, isolated from the high-altitude volcanic Diamante Lake in the northwest of Argentina, was completely sequenced and annotated. It is noteworthy that the element is probably conjugative and harbors genes potentially instrumental in coping with stress conditions that prevail in such an extreme environment.

Killer Yeast, a Novel Biological Control of Soilborne Diseases for Good Agriculture Practice

Aspergillus niger (A. niger) causes a disease called black mold on certain fruits and vegetables such as grapes, apricots, onions, and peanuts and is a common contaminant of food. Containment of this disease can reduce the amount of fruits, vegetables, and foods to be discarded, hence reducing the amounts of agricultural waste generated. Chemical control of A. niger has been partially successful, and fungicides are commonly used in the management of black mold. However, the risk of the establishment of resistant Aspergillus strains is considerable. Biocontrol, a nonhazardous alternative to the use of chemical fungicides, involves the use of biological processes to reduce crop loss and various microorganisms. Since it was first reported, the killer phenomenon in yeasts has been extensively studied in several genera and species, and its importance is gaining further recognition by industrialists. The food and beverage industries were among the first to explore the ability of toxin-producing yeasts to kill other fungus.

Complete Genome Sequences of pLMA1 and pLMA7, Two Large Linear Plasmids of Micrococcus Strains Isolated from a High-Altitude Lake in Argentina

ABSTRACT The two linear plasmids pLMA1 (109,112 bp) and pLMA7 (82,075 bp) from Micrococcus strains were isolated from a high-altitude lake in the Argentinean Puna, sequenced, and annotated. These extrachromosomal elements are probably conjugative and harbor genes potentially involved in coping with the harsh conditions in such extreme environments.

Water and Flamingo Feces Bacterial Communities from High- Altitude Andean Lakes under Selective Antibiotic Pressure Studied by PCR-DGGE Analyses

High-altitude Andean lakes are exposed to extreme environmental factors like high salin‐ ity, ultraviolet radiation, heavy metals, among others. As it was previously shown, these lakes are not only the habitat of a high diversity of bacteria with multiple resistances; they also support an enormous population of flamingos, which migrate among these wet‐ lands, and they could play a role as disseminators and/or reservoirs of pathogenic bacte‐ ria. The aim of this work was to analyze, by Denaturant Gradient Gel Electrophoresis, the bacterial population under selective antibiotic pressure from bacterioplankton and fla‐ mingo feces from three lakes, placed between altitudes 4,200 and 4,560 m. Almost all bands were present in antibiotic-enriched cultures. Several bands identified in water were found in feces as well, presenting mainly correspondence with Gamma-proteobacte‐ ria. Few bands were exclusively identified in water, and those presenting correspondence with Alfa-proteobacteria and Actinobacteria were only identified in Laguna Azul. This study established that flamingos’ enteric biota is in close interaction with lake water and demonstrated that bacteria with the ability to grow in antibiotics are abundant and diverse in the microbiota of Andean lakes. Additionally, flamingos could be considered as vectors of pathogenic organisms, since Stenotrophomonas seem to be the widest spread bacteria in the studied lakes.