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KURT HANSELMANN

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Author-ID : 274781

Agriculture, Biological Sciences & Forestry Biochemistry, Genetics & Molecular Biology Immunology & microbiology Medicine & Pharmacology Veterinary

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Free-Living Ice-Nucleating Active Bacteria from High Mountain Lake Habitats MUNTI YUHANA; KURT HANSELMANN
Microbiology Indonesia Vol. 2 No. 3 (2008): December 2008
Publisher : Indonesian Society for microbiology

We collected the culturable heterotrophic bacteria from oligotrophic high mountain lake habitats and tested their capability to induce ice formation. Direct plating was carried out using low-nutrient medium at a temperature of between 3 and 4°C. As many as 84 isolates were recovered from glacial ice and natural biofilm growing on granite rocks surface. Six out of 84 isolates were capable of expressing the ice-nucleation phenotype. After autoclaving the cell suspension at 121°C for 15 min, isolate J78 was still able to retain the ability for ice formation. Heat-stable ice nuclei produced by ice-nucleating active bacteria have potential applications in biotechnology. Characterization of INA bacteria was performed employing live-dead Gram staining and molecular methods. Universal primers for Bacteria (S-D-Bact-0008-b-S-20 and S-D-Bact-1524-a-A-18) were used for PCR to amplify almost the full length of the 16S rRNA genes of selected INA isolates. Restriction fragment length polymorphism analysis resulted in 2 unique patterns, as represented by J43 and J83, respectively. Based on DNA sequencing of 16S rRNA gene, isolate J43 (GeneBank accession no. AJ864852) was closely related to Pseudomonas mephitica (99.2% sequence similarity) and Janthinobacterium lividum (99% similarity), whereas isolate J83 (GeneBank accession no. AJ864859) showed 100% sequence identity to Pseudomonas fluorescens.

CURRENT MICROBIOLOGICAL ASPECTS IN HIGH MOUNTAIN LAKE RESEARCH YUHANA, MUNTI; HANSELMANN, KURT
BIOTROPIA Vol. 13 No. 1 (2006): BIOTROPIA Vol. 13 No. 1 June 2006
Publisher : SEAMEO BIOTROP

Remote and normally unpolluted high mountain lakes provide habitats with no or very limited anthropogenic influences and, therefore, their hydrodynamics are mostly regulated by the natural conditions. Researches in high mountain lakes deal with measuring and modeling the response of the habitats to environmental changes especially correlated to acid deposition, pollutants influx and climatic variability. The microbial world has also become a focus in many studies of these extreme ecosystems. Despite the pressure of harsh and extreme conditions, microbial communities living in these habitats developed flexible strategies and show quick adaptation to climate oscillation. New aspects in microbiological studies in recent high mountain lake research are presented in this paper.Key words : High mountain lake, extreme environment, microbial communities, microbial diversity, psychrotolerant microbe, molecular microbe

BACTERIAL COMMUNITY SHIFTS OF A HIGH MOUNTAIN LAKE IN RESPONSE TO VARIABLE SIMULATED CONDITIONS: AVAILABILITY OF NUTRIENTS, LIGHT AND OXYGEN YUHANA, MUNTI; HORATH, THOMAS; HANSELMANN, KURT
BIOTROPIA Vol. 13 No. 2 (2006): BIOTROPIA Vol. 13 No. 2 December 2006
Publisher : SEAMEO BIOTROP

We studied bacterial population composition shifts by exposing natural water samples to variable simulated environmental conditions. The samples were taken from Lake Jori XIII (2640 m a.s.l), an oligo-to mesotrophic cold freshwater lake, located in the eastern Swiss Alps. The Jori lakes are characterized as remote, unpolluted high mountain lakes with a long period of ice cover and typically low nutrient concentrations. Culture independent techniques (PCR-based analyses) were used for detection and molecular characterization of a large number of bacteria most of which are still uncultivable. Bacterial community shifts over three ecological conditions (nutrients, light and oxygen availability) were detected by using Temporal Temperature gradient Gel Electrophoresis (TTGE) of a PCR-amplified part of the 16S rRNA gene. The bacterial populations responded differently to the variable conditions, as revealed by TTGE pattern shifts during the experiment. Key words: Temporal Temperature gradient Gel Electrophoresis (TTGE), ARB, small subunit ribosomal RNA gene (SSU rRNA gene), alpine freshwater lake JOri XIII, PCR

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