Hans Fricke

Aquifex pyrophilus gen.nov. sp. nov., represents a novel group of marine hyperthermophilic hydrogen-oxidizing bacteria

Summary From hot marine sediments (depth: 106 m) at the Kolbeinsey Ridge, Iceland, novel bacterial hyperthermophiles were isolated. Cells were Gram-negative highly motile rods exhibiting a complex envelope consisting of murein, an outer membrane and a surface protein layer. Growth occurred between 67 and 95 °C (opt.: 85 °C; 75 min doubling time), pH 5.4 and 7.5 (opt.: pH 6.8), and 1 to 5% NaCl (opt.: 3% NaCl). The novel isolates were strict chemolithoautotrophs. They used molecular hydrogen, thiosulfate and elemental sulfur as electron donors and oxygen (low concentrations) and nitrate as electron acceptors. During growth, sulfuric acid was formed from S° and thiosulfate. In the late logarithmic growth phase, H2S was formed from S° and H2. The core lipids consisted mainly of alkyl ethers of glycerol. The GC content of the DNA was 40 mol%. By 16S rRNA comparisons, the new isolates did not belong to any of the phyla known and represent the deepest phylogenetic branch-off within the Bacteria domain. Based on the physiological and molecular properties of the new isolates, we describe here a new genus, which we name Aquifex (the “water-maker”). The type species is Aquifex pyrophilus (type strain: Kol5a; DSM 6858).

Methanopyrus kandleri, gen. and sp. nov. represents a novel group of hyperthermophilic methanogens, growing at 110°C

A novel group of hyperthermophilic rod-shaped motile methanogens was isolated from a hydrothermally heated deep sea sediment (Guaymas Basin, Gulf of California) and from a shallow marine hydrothermal system (Kolbeinsey ridge, Iceland). The grew between 84 and 110°C (opt: 98°C) and from 0.2% to 4% NaCl (opt. 2%) and pH 5.5 to 7 (opt: 6.5). The isolates were obligate chemolithoautotrophes using H2/CO2 as energy and carbon sources. In the presence of sulfur, H2S was formed and cells tended to lyse. The cell wall consisted of a new type of pseudomurein containing ornithin in addition to lysine and no N-acetylglucosamine. The pseudomurein layer was covered by a detergent-sensitive protein surface layer. The core lipid consisted exclusively of phytanyl diether. The GC content of the DNA was 60 mol%. By 16S rRNA comparisons the new organisms were not related to any of the three methanogenic lineages. Based on the physiological and molecular properties of the new isolates, we describe here a new genus, which we name Methanopyrus (the “methane fire”). The type species is Methanopyrus kandleri (type strain: AV19; DSM 6324).

Thermotoga thermarum sp. nov. and Thermotoga neapolitana occurring in African continental solfataric springs

Three new strains of eubacterial hyperthermophiles were isolated from continental solfataric springs at Lac Abbé (Djibouti, Africa). Due to their morphology, lipids, and RNA polymerases they belong to the genus Thermotoga. Strains LA4 and LA10 are closely related to Thermotoga neapolitana found up to now only in the marine environment. Strain LA 3 differs from Thermotoga maritima and Thermotoga neapolitana in significant physiological and molecular properties. It is described as the new species Thermotoga thermarum.

Interspecific communicative and coordinated hunting between groupers and giant moray eels in the Red Sea.

Intraspecific group hunting has received considerable attention because of the close links between cooperative behaviour and its cognitive demands. Accordingly, comparisons between species have focused on behaviours that can potentially distinguish between the different levels of cognitive complexity involved, such as “intentional” communication between partners in order to initiate a joint hunt, the adoption of different roles during a joint hunt (whether consistently or alternately), and the level of food sharing following a successful hunt. Here we report field observations from the Red Sea on the highly coordinated and communicative interspecific hunting between the grouper, Plectropomus pessuliferus, and the giant moray eel, Gymnothorax javanicus. We provide evidence of the following: (1) associations are nonrandom, (2) groupers signal to moray eels in order to initiate joint searching and recruit moray eels to prey hiding places, (3) signalling is dependent on grouper hunger level, and (4) both partners benefit from the association. The benefits of joint hunting appear to be due to complementary hunting skills, reflecting the evolved strategies of each species, rather than individual role specialisation during joint hunts. In addition, the partner species that catches a prey item swallows it whole immediately, making aggressive monopolisation of a carcass impossible. We propose that the potential for monopolisation of carcasses by one partner species represents the main constraint on the evolution of interspecific cooperative hunting for most potentially suitable predator combinations.

Pyrodictium abyssi sp. nov. represents a novel heterotrophic marine archaeal hyperthermophile growing at 110°C

Summary Novel hyperthermophilic heterotrophic members of the Archaea domain were isolated from marine hot abyssal as well as from shallow vents off Mexico and Iceland, respectively. The isolates grew between 80 and 110°C with an optimum around 97°C. They fermented carbohydrates, proteins, cell homogenates, acetate and formate. Isovalerate, isobutyrate, butanol and CO2 were detected as end products. Growth was stimulated by H2. In the presence of S°, H2S was formed. Cells were disk-shaped and appeared entrapped within networks of fibres. Based on DNA/DNA homology and 16 S rRNA partial sequences, the new isolates represent a new species of Pyrodictium, which we name Pyrodictium abyssi. Type strain is isolate AV2 (DSM 6158).

Thermosipho africanus gen. nov., Represents a New Genus of Thermophilic Eubacteria within the “Thermotogales”

Summary Three isolates of thermophilic eubacteria were obtained from a marine hydrothermal area at Obock (Djibouti, Africa). The rodshaped cells were surrounded by a sheath-like outer structure, similar to members of the genus Thermotoga . In contrast to Thermotoga , the new bacteria grew in chains (up to twelve rods) surrounded by the sheath. Furthermore, the isolates could be clearly distinguished from Thermotoga by a 11% lower GC-content, an immunologically divergent RNA polymerase, and a much lower growth temperature. 16S rRNA sequencing indicated that the new organisms were related to Thermotoga at the level of a second genus within the “Thermotogales” , which we name Thermosipho . Isolate Ob7 is described as the type species Thermosipho africanus .

Hydrothermal vent communities at the shallow subpolar Mid-Atlantic ridge

A new type of animal community has been found near hot vents in the subpolar Atlantic at 100 to 106 m depth off Kolbeinsey on the Jan-Mayen ridge. Incubation of high temperature fluids yielded cultures of undescribed hyperthermophilic eu- and archaebacteria, growing in a temperature range between 70° and 110°C depending on the isolates. Bacteria are closely related to species occurring within deep sea hydrothermal areas. In contrast to deep-sea vent sites of the Mid-Atlantic and other oceans, the Kolbeinsey macro- and meiofauna consists of species reported from non-vent areas in the boreal Atlantic and adjacent polar seas. The most abundant forms are a solitary hydroid polyp and two sponges. Kolbeinsey is an isolated and young area of hydrothermal activity at relatively low depth and in highly productive waters; these findings could indicate a model for an early evolutionary step towards the formation of a genuine specialized vent community.

Control of different mating systems in a coral reef fish by one environmental factor

Abstract The Red Sea coral-dwelling damselfish Dascyllus marginatus is organized in stable terri torial groups with males dominating all females. The fish live in pairs, harems or multi-male groups. Group size, and the number of sexually active males in a group, are correlated with coral size. Males monopolize and control the coral, attracting potential mates. The experimental alteration of coral sizes, using spherical Stylophora corals, resulted in an increase of male numbers, in artificially composed groups, with the increase of coral size. Thus pairs and harems were produced on small corals, multimale groups on big corals. Experiments with unisexual groups revealed a higher survival of females; males are more aggressive to each other, and cause a stronger emigration of subdominants. In D. marginatus , group size and the number of sexually active males are essentially restricted by one environmental factor: the number of available hiding places on a coral.

Light harvesting by wavelength transformation in a symbiotic coral of the Red Sea twilight zone

We report an extraordinary depth range for Leptoseris fragilis (Milne Edwards and Haime), a reef building coral of the Red Sea living in cytosymbiosis with zooxanthellae. The coral harbours an as yet unknown pigment system. We suggest that the heterotrophic host — the coral — provides its photoautotrophic symbionts with additional light. The supplementary light is provided by host pigments which transform light of short wavelengths into suitable wavelengths for photosynthesis, thus amplifying and increasing the transfer of photoassimilates from the zooxanthellae to the host.

Seamounts, new moon and eel spawning: The search for the spawning site of the Japanese eel

After analyzing all the collection data for larvae of the Japanese eel, Anguilla japonica, in the western North Pacific, we found that the spawning site of this species appears to be near three seamounts in the West Mariana Ridge, 2000–3000 km away from their freshwater habitats. These seamounts are located in the westward flow of the North Equatorial Current and are hypothesized to provide cues for migrating silver eels and to serve as possible aggregation sites for spawning. Back-calculated birth dates based on otolith microstructure of leptocephali indicate that the Japanese eel does not spawn continuously during the long spawning season from April to November, but is synchronized to spawn periodically once a month during new moon. This lunar periodicity of spawning and the seamount spawning hypothesis are new developments in the millennium-old mystery of eel spawning that has fascinated naturalists since the time of Aristotle.