Microorganisms in the atmosphere over Antarctica.

Antarctic microbial biodiversity is the result of a balance between evolution, extinction and colonization, and so it is not possible to gain a full understanding of the microbial biodiversity of a location, its biogeography, stability or evolutionary relationships without some understanding of the input of new biodiversity from the aerial environment. In addition, it is important to know whether the microorganisms already present are transient or resident - this is particularly true for the Antarctic environment, as selective pressures for survival in the air are similar to those that make microorganisms suitable for Antarctic colonization. The source of potential airborne colonists is widespread, as they may originate from plant surfaces, animals, water surfaces or soils and even from bacteria replicating within the clouds. On a global scale, transport of air masses from the well-mixed boundary layer to high-altitude sites has frequently been observed, particularly in the warm season, and these air masses contain microorganisms. Indeed, it has become evident that much of the microbial life within remote environments is transported by air currents. In this review, we examine the behaviour of microorganisms in the Antarctic aerial environment and the extent to which these microorganisms might influence Antarctic microbial biodiversity.

Marinobacter lacisalsi sp. nov., a moderately halophilic bacterium isolated from the saline-wetland wildfowl reserve Fuente de Piedra in southern Spain.

A Gram-negative, non-spore-forming, motile, moderately halophilic, aerobic, rod-shaped bacterium, designated strain FP2.5(T), was isolated from the inland hypersaline lake Fuente de Piedra, a saline-wetland wildfowl reserve located in the province of Málaga in southern Spain. Strain FP2.5(T) was subjected to a polyphasic taxonomic study. It produced colonies with a light-yellow pigment. Strain FP2.5(T) grew at salinities of 3-15 % (w/v) and at temperatures of 20-40 degrees C. The pH range for growth was 5-9. Strain FP2.5(T) was able to utilize various organic acids as sole carbon and energy source. Its major fatty acids were C(16 : 0), C(18 : 1)omega9c and C(16 : 1)omega9c. The DNA G+C content was 58.6 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain FP2.5(T) appeared to be a member of the genus Marinobacter and clustered closely with the type strains of Marinobacter segnicrescens, Marinobacter bryozoorum and Marinobacter gudaonensis (levels of 16S rRNA gene sequence similarity of 98.1, 97.4 and 97.2 %, respectively). However, DNA-DNA relatedness between the new isolate and the type strains of its closest related Marinobacter species was low; levels of DNA-DNA relatedness between strain FP2.5(T) and M. segnicrescens LMG 23928(T), M. bryozoorum DSM 15401(T) and M. gudaonensis DSM 18066(T) were 36.3, 32.1 and 24.9 %, respectively. On the basis of phenotypic characteristics, phylogenetic analysis and DNA-DNA relatedness data, strain FP2.5(T) is considered to represent a novel species of the genus Marinobacter, for which the name Marinobacter lacisalsi sp. nov. is proposed. The type strain is FP2.5(T) (=CECT 7297(T)=LMG 24237(T)).

Halomonas indalinina sp. nov., a moderately halophilic bacterium isolated from a solar saltern in Cabo de Gata, Almeria, southern Spain.

A moderately halophilic bacterium, strain CG2.1T, isolated from a solar saltern at Cabo de Gata, a wildlife reserve located in the province of Almería, southern Spain, was subjected to a polyphasic taxonomic study. This organism was an aerobic, motile, Gram-negative rod that produced orange-pigmented colonies. Strain CG2.1T was able to grow at salinities of 3-25 % (w/v) and at temperatures of 15-40 degrees C. The pH range for growth was 5-9. Strain CG2.1T was a heterotroph capable of utilizing various carbohydrates as carbon sources. The organism reduced nitrate and showed phenylalanine deaminase activity. The major fatty acids were C(18 : 1)omega7c, C(16 : 0) and C(19 : 0) cyclo omega8c. The DNA G+C content was 60.9 mol%. On the basis of the phenotypic and phylogenetic data, strain CG2.1T appeared to be a member of the genus Halomonas and clustered closely with Halomonas marisflavi (97.1 % 16S rRNA gene sequence similarity). However, the level of DNA-DNA relatedness between the novel isolate and the most closely related Halomonas species was low. On the basis of these data, strain CG2.1T represents a novel member of the genus Halomonas, for which the name Halomonas indalinina is proposed. The type strain is CG2.1T (=CECT 5902T=LMG 23625T).

Chromohalobacter salarius sp. nov., a moderately halophilic bacterium isolated from a solar saltern in Cabo de Gata, Almeria, southern Spain.

A moderately halophilic, Gram-negative bacterium (strain CG4.1(T)), which was isolated from a solar saltern at Cabo de Gata, a wildlife reserve located in the province of Almería, southern Spain, was subjected to a polyphasic taxonomic study. This organism was an aerobic, motile rod that produced colonies with a yellow pigment. Strain CG4.1(T) grew at salinities of 3-25 % (w/v), at 15-45 degrees C and at pH 5-9. The organism reduced nitrate, hydrolysed starch and had phenylalanine deaminase activity. The major fatty acids were C(18 : 1)omega7c, C(16 : 0) and C(19 : 0) cyclo omega8c. The DNA G+C content was 63.6 mol%. On the basis of phenotypic and phylogenetic data, strain CG4.1(T) appears to be a member of the genus Chromohalobacter and clustered closely with Chromohalobacter species, with 95-96 % similarity between their 16S rRNA gene sequences. However, DNA-DNA relatedness between the isolate and the type strains of Chromohalobacter species was low. Therefore, it is proposed that strain CG4.1(T) represents a novel species, Chromohalobacter salarius sp. nov. The type strain is strain CG4.1(T) (=CECT 5903(T)=LMG 23626(T)).

Antarctic Dry Valley mineral soils contain unexpectedly high levels of microbial biomass.

We have applied bioluminescent ATP detection methods to microbial enumeration in Antarctic Dry Valley mineral soils, and validated our ATP data by two independent methods. We have demonstrated that ATP measurement is a valid means of determining microbial biomass in such sites, and that the desiccated surface mineral soils of the Antarctic Dry Valleys contain cell numbers over four orders of magnitude higher than previously suggested.