Genki I. Matsumoto

Arthrobacter flavus sp. nov., a psychrophilic bacterium isolated from a pond in McMurdo Dry Valley, Antarctica

CMS 19YT, a psychrophilic bacterium, was isolated from a cyanobacterial mat sample from a pond in Antarctica and was characterized taxonomically. The bacterium was aerobic, gram-positive, non-spore-forming, non-motile, exhibited a rod-coccus growth cycle and produced a yellow pigment that was insoluble in water but soluble in methanol. No growth factors were required and it was able to grow between 5 and 30 degrees C, between pH 6 and pH 9 and tolerated up to 11.5% NaCl. The cell wall peptidoglycan was Lys-Thr-Ala3 (the A3alpha variant) and the major menaquinone was MK-9(H2). The G+C content of the DNA was 64+/-2 mol%. The 16S rDNA analysis indicated that CMS 19YT is closely related to group I Arthrobacter species and showed highest sequence similarity (97.91%) with Arthrobacter agilis. Furthermore, DNA-DNA. hybridization studies also indicated 77% homology between CMS 19YT and A. agilis. It differed from A. agilis, however, in that it was psychrophilic, non-motile, yellow in colour, exhibited a rod-coccus growth cycle, had a higher degree of tolerance to NaCl and was oxidase- and urease-negative and lipase-positive. In addition, it had a distinct fatty acid composition compared to that of A. agilis: the predominant fatty acids were C15:0, anteiso-C15:0, C16:0, iso-C16:0, C17:0, anteiso-C17:0 and C18:0. It is proposed, therefore, that CMS 19YT should be placed in the genus Arthrobacter as a new species, i.e. Arthrobacter flavus sp. nov. The type strain of A. flavus is CMS 19YT (= MTCC 3476T).

Planococcus antarcticus and Planococcus psychrophilus spp. nov. isolated from cyanobacterial mat samples collected from ponds in Antarctica

Abstract. Thirteen orange-pigmented bacteria associated with cyanobacterial mat samples collected from four different lakes in McMurdo, Antarctica, were isolated. Twelve of the isolates, which were coccoid in shape, were very similar and possessed all the characteristics of the genus Planococcus and represented a new species, which was assigned the name Planococcus antarcticus sp. nov. (CMS 26orT). Apart from the phenotypic differences, P. antarcticus differed from all reported species of Planococcus by more than 2.5% at the 16S rRNA gene sequence level. In addition, at the DNA–DNA hybridization level, it exhibited very little similarity either with P. mcmeekinii (30%–35%), P. okeanokoites (26%–29%), or CMS 53orT (15%–25%), the three species with which it is closely related at the rRNA gene sequence level (2.5%–2.9%). P. antarcticus also showed only 2.5% difference in its 16S rRNA gene sequence compared with the P. alkanoclasticus sequence. But it was distinctly different from P. alkanoclasticus, which exists only as rods, is mesophilic and phosphatase positive, can hydrolyze starch, cannot utilize succinate, glutamate, or glucose, and cannot acidify glucose. Most important, P. antarcticus and P. alkanoclasticus varied distinctly in their fatty acid composition in that C15:0, C15:1, C16:0, iso-C16:1, and C17:0 were present only in P. antarcticus but absent in P. alkanoclasticus. CMS 53orT, the thirteenth isolate, was also identified as a new species of Planococcus and was assigned the name Planococcus psychrophilus sp. nov. This species was distinctly different from all the reported species, including the new species P. antarcticus, with respect to a number of phenotypic characteristics. At the 16S rRNA gene sequence level, it was closely related to P. okeanokoites (98.1%) and P. mcmeekinii (98%), but with respect to the DNA–DNA hybridization, the similarity was only 35%–36%. The type strain of P. antarcticus is CMS 26orT (MTCC 3854; DSM 14505), and that of P. psychrophilus is CMS 530rT (MTCC 3812; DSM 14507).

Arthrobacter roseus sp. nov., a psychrophilic bacterium isolated from an Antarctic cyanobacterial mat sample

Strain CMS 90rT, a red-pigmented bacterium, was isolated from a cyanobacterial mat sample from a pond located in McMurdo, Antarctica. Based on its chemotaxonomic and phylogenetic properties, strain CMS 90r(T) was identified as a member of group I of Arthrobacter. It shared 16S rDNA similarity of 98% with Arthrobacter oxydans ATCC 14358T and Arthrobacter polychromogenes ATCC 15216T, while DNA-DNA similarities determined for these three organisms were less than 70%. It also differed from all 17 reported Arthrobacter species with A3alpha-variant peptidoglycan in that it possessed a unique peptidoglycan (Lys-Gly-Ala3) and contained galactose, glucose, ribose and rhamnose as cell-wall sugars. These data and the presence of diagnostic phenotypic traits support the description of CMS 90r(T) as a novel species of Arthrobacter, for which the name Arthrobacter roseus sp. nov. is proposed. The type strain is strain CMS 90r(T) (= MTCC 3712T = DSM 14508T).

Vertical distribution of organic constituents in an Antarctic lake: Lake Fryxell

Vertical distribution of organic constituents, i.e. total organic carbon (TOC), extractable organic carbon with ethyl acetate (EOC), hydrocarbons, phytol, sterols, fatty acids and phenolic acids in Lake Vanda was studied to elucidate their features in relation to the stratification of lake water and the distribution of lake organisms. The concentrations of TOC, EOC and sterols increased with depth and attained the maximum values of 25 and 1.5 mgC l−1 and 1.4 μg l−1 in the bottom, respectively, while those of fatty acids showed the maximum value of 61 μg l−1 at a depth of 55.4 m, along with the highest value of the ratio of unsaturated (UC16, uC18) to saturated (C16, C18) acids (8.5) and with the highest carbon preference index (35). Hydrocarbons were only found in the bottom layers (60.4 and 65.9 m) and bottom sediment. These results suggest strongly that the vertical distribution of lake organisms and their activity are quite different due to depth. In the bottom warm anoxic layers the degradation of organic materials must have occurred significantly and thus refractory organic materials should be concentrated.

Unusual distributions of long-chain n-alkanes and n-alkenes in antarctic soil.

Abstract Hydrocarbons in soil samples from the McMurdo Dry Valleys of southern Victoria Land, Antarctica, were studied to examine their features and to elucidate source materials. Normal-alkanes and n -alkenes were found at concentrations ranging from 13 to 2200 and from 1.1 to 5000 ng/g of dry soil, respectively. Unexpectedly, the major hydrocarbons were all odd-carbon numbered long-chain n -alkanes with maximum concentrations n -C 23 , n C 25 or n -C 27 . This may be due to the erosion of sedimentary materials containing vascular plant debris formed during the pre- and inter-glaciation periods of Antarctica (Miocene-Pliocene) and microbial debris, such as fungi and microalgae. Normal-alkenes maximize at n -C 23:1 (carbon chain length: number of double bonds), n -C 25:1 , n -C 27:1 or n -C 29:2 , which could be derived from cyanobacteria and microalgae, that lived in the past in the Antarctic cold desert and/or organic debris of wind-transported cyanobacterial mats.

Hydroxy acids in Antarctic lake sediments and their geochemical significance

Abstract Hydroxy acids in sediments of Lakes Bonney, Fryxell, Joyce and Vanda, and unnamed ponds (B2, NF1, NF2 and L4) as well as in cyanobacterial mats from the McMurdo Sound region of southern Victoria Land in Antarctica have been studied to clarify their features and elucidate their source organisms. Normal and branched ( iso and anteiso ) 2-hydroxy acids were found in all the samples studied with the predominance of even- and odd-carbon numbers, respectively. The most dominant 2-hydroxy acids in the sediments were mainly short-chain components ( 20 ). Normal and branched 3-hydroxy acids were detectewith the predominance of even- and odd-carbon numbers, respectively, in total concentrations between 0.48 and 53 μg/g of dry sediment. (ω-1)-Hydroxy acids were all long-chains (C 22 , C 24 , C 26 , C 28 and C 30 ). 9,10-Dihydroxyhexadecanoic and/or 9,10-dihydroxyoctadecanoic acids were identified in all the sediments and a cyanobacterial mat. The composition of hydroxy acids differ considerably among the lakes and ponds, suggesting the difference of source organisms. These 2-, 3- and (ω-1)-hydroxy, and 9,10-dihydroxy acids may be derived from cyanobacteria and microalgae, in addition to non-photosynthetic microorganisms. Cyanobacteria and microalgae which are widely distributed in the world, may be important sources of hydroxy acids in the natural environments.

Organic geochemistry of the McMurdo Dry Valleys soil, Antarctica.

Abstract Organic geochemical studies of 12 soil samples from Wright and Taylor Valleys of the McMurdo Dry Valleys (Ross Desert) in southern Victoria Land, Antarctica, were carried out. Long-chain n -alkanoic acids (C 20 −C 34 ), with predominance of even-carbon numbers, were abundant in all the samples. 3-Hydroxy acids (C 8 -C 30 ) with a predominance of even-carbon numbers were found in the samples, together with 2-, ω- and (ω-1)-hydroxy acids. α,ω-Dicarboxylic acids (C 8 -C 31 ) were detected having near-unity values of carbon preference indices; mainly the C 13 dicarboxylic acid predominated. Visual kerogen revealed that amorphous materials are major components (68–98%) with small amounts of very fine coals (2–32%), but no woody and herbaceous materials. The occurrence of mature isomers of steranes and triterpanes, the paucity of n -alkenoic acids and data from the microscopic study suggest that organic components in the soil samples are derived from erosion of Beacon Supergroup sedimentary rocks and past biological debris containing vascular plan waxes as well as wind-transported cyano-bacterial mats, including cyanobacteria, microalgae, bacteria and fungi, rather than from living organisms.

Hydrocarbons and fatty acids in two strains of the hot spring alga Cyanidium caldarium

Abstract Normal alkanes (n-C14-n-C30) and a diene (C19:2) were found in Cyanidium caldarium RK-1 type with predominance of n-C17, (46.3 %), while Cyanidium M-8 type contained n-alkanes (n-C15-n-C25) and alkenes (C19:1,C21:1) with an abundance of C19:1 (43.4 %). Normal alkanoic acids of odd-carbon numbers, n-C15 (12.7%) and n-C17,(10.5%) aswell as of even-carbon numbers, n-C16 (12.7%) and n-C18 (9.8%) and C18:2 alkenoic acid (53.1%) were found in Cyanidium RK-1, while Cyanidium M-8 mainly contained n-C16 (33.5 %) alkanoic acids, C18:1(33.3 %) and C18:2 (23.7%) alkenoic acids. The acid C18:2 was present only in Cyanidium M-8. These results indicate a considerable difference between the two strains of Cyanidium caldarium, and Cyanidium RK-1 type may be unique among microalgae because it has a significant amount of odd-carbon numbered n-alkanoic acids.

Steranes and triterpanes in the Beacon Supergroup samples from southern Victoria Land in Antarctica

Steranes and triterpanes in Beacon Supergroup samples (sedimentary rock and silicified wood) from Allan Hills and Carapace Nunatak of southern Victoria Land in Antarctica were studied to elucidate sources of organic materials, sedimentary paleoenvironment and thermal history after deposition. Relative abundances of C27, C28 and C29 steranes and visual kerogen results of Beacon Supergroup samples from Allan Hills imply that organic materials in the sedimentary paleoenvironments are contributed mainly by vascular plants with some influence of microorganisms, while those of the Carapace Nunatak sample may be largely due to fern spores. The pristanephytane and pristaneheptadecane ratios of the samples were generally close to unity and between 0.50 and 0.99, respectively, suggesting that the sedimentary paleoenvironment was shallow lacustrine with alternating oxic and anoxic conditions. The (22S22R)-17α(H),21β(H)-C31-C33 triterpane ratios are approximately at thermal equilibrium values (ca. 1.5) in most samples, while the (20S20R)-5α(H), 14α(H), 17α(H)-C29 sterane ratios and the (20R + 20S)-5α(H), 14β(H), 17β(H)5α(H), 14α(H), 17α(H)-C29 sterane ratios vary from 0.0 to 1.1 and from 0.0 to 1.4, respectively. Most of the (20S20R)-5α(H), 14α(H), 17α(H)-C29 sterane ratios did not reach thermal equilibrium values. The correlation coefficient between the (20S20R)-5α(H), 14α(H), 17α(H)-C29 sterane ratios and (20R + 20S)-5α(H), 14β(H), 17β(H)5α(H), 14α(H), 17α(H)-C29, sterane ratios is very high (0.96). These variable maturities probably reflect thermal effects of basaltic dikes on the Beacon Supergroup at Allan Hills and Carapace Nunatak during Jurassic time. Thermal stresses on the Beacon Supergroup prior to basaltic intrusion have been estimated to be quite low, so the paleotemperatures of this formation have been quite low.

Paleoenvironmental Changes in the Eurasian Continental Interior during the Last 12 Million Years Derived from Organic Components in Sediment Cores (BDP-96 and BDP-98) from Lake Baikal

Organic components in combined sediment cores (BDP-96 and BDP-98) of BDP-96-1 and -2 (200 m) and BDP-98-1 and -2 (600 m) from Academician Ridge in Lake Baikal, in south-central Siberia, were studied to clarify the biological production, sources of organic matter, and paleoenvironmental changes during the last 12 million years (Myr) in the Eurasian continental interior as well as in the world. Total organic carbon (TOC) contents ranging from 0.13% to 2.8%, with an average of 0.93% (n = 7710), were fairly low, and were similar to those found in some oligotrophic lakes. TOC and total nitrogen (TN) contents had decreased by about half from 12 Myr ago to the present as a result of global climate cooling. Higher biological production periods are mainly attributed to the contribution of vascular plants.