LOMROG III 3rd field report
The search for bioactive Arctic marine bacteria
The 'Core catcher' of the piston corer from which surplus sediment is sampled for microbial analyses. (Photo: Ragner Jerre)
Marie Lykke Rasmussen and Nikolaj retrieves an ice core. (Photo: Gorm Dybkjær)
Arctic sediment samples inoculated on nutrient poor growth substrate. (Photo: Nikolaj Vynne)
21.st of August
Position 89° 7' N, 57° 36' W
Weather: Cloudy, 0 °C, 13 m/s wind
Text: Nikolaj Vynne, National Food Institute, Technical University of Denmark
Icebreaker Oden is north of the 89th latitude and solid ice covers the sea. I stand ready with a sterile plastic tube to obtain another of the samples which I have coveted for months. Some of the geologists on board the Oden are retrieving a sample of the sea bed using a technique called 'piston coring' and while their interest concerns the sediment deposits which make up the seabed itself, my interest is the microorganisms which have made a home in the Arctic mud. The sample is ready now, several meters of sediment core lies on the aft deck and from a surplus part of the core I withdraw the roughly 200 grams of mud necessary for my work.
The interest in Arctic microorganisms stems from a desire to investigate the so-called 'bioactive' compounds produced by some marine bacteria, and to understand both which culture conditions enable production of such compounds and which roles the compounds play in microbial ecology. The hope is that a better understanding of marine bacteria and their interactions may contribute to overcoming challenges such as the lack of novel antibiotics effective against multiresistant disease causing bacteria. The Arctic is an interesting area as a source of bioactive marine bacteria, as previous investigations have shown the presence of such bacteria yet very few are in culture in laboratories and their bioactive potential remains largely unknown.
While on board the Oden this project is centered on sample collection from primarily mud and sediments, and processing the samples for safe storage until they can be analyzed back at the university laboratory. In addition to sediment and mud, samples are also obtained from sea water which is collected by the oceanographers on board, from ice cores and other interesting sources such as copepods. As one of the smaller research projects on board Oden, it is an immense advantage to collaborate with the oceanographic and geology projects. This provides access to sample material which otherwise would be practically impossible to obtain.
Once a sample is taken for microbial analyses, it will typically be split in two plastic tubes and processed in order to ensure the microorganisms in the sample will survive storage and transport to the laboratory. One tube is added glycerol to protect against frost related damage and then stored at -80°C. The other tube is stored unprocessed at 4°C. Preliminary analysis of the sediment samples is initiated on board by inoculating sediment on a special nutrient poor growth substrate which is then incubated at 4 °C. Being able to culture a given bacterial strain is an essential prerequisite for many laboratory procedures, and the idea here is to create a growth environment resembling the original sample from which the bacteria were obtained. Once the research cruise has ended a substantial effort awaits in order to analyze the bioactive potential of the marine bacteria brought home in these high Arctic samples.