Table 1.
Comparative properties of strains AArcel7T, A-rgal3, and members of the genus Natrarchaeobius*.
| Property | AArcel7T | A-rgal3 | Natrarchaeobius chitinivorans | Natrarchaeobius halalkaliphilus AArcht-SlT | |
|---|---|---|---|---|---|
| AArcht4T | AArcht7 | ||||
| Phenotypic properties | |||||
| Cell morphology | Polymorphic rods and coccoids, motile | Dimorphic: flat motile rods on sugars; nonmotile cocci on chitin | |||
| Colonies on amorphous chitin agar | Compact with large chitin clearance, pale | Spreading with small chitin clearance, pale | Compact, with large chitin clearance, pink | Compact, with large chitin clearance, pale | |
| Colonies on amorphous cellulose agar | Compact with small clearance, pink | No growth | No growth | No growth | |
| Utilized polysaccharides (apart from chitin) | Laminarin, xyloglucan (w), xylan, arabinoxylan, barley beta-glucan (w), galactan (w), starch, pullulan | Laminarin, xylan (w), barley beta-glucan (w), starch, pullulan | None | ||
| Utilized sugars | glucose, fructose, sucrose, mannose, raffinose, Naga**, glucosamine, lactose, fucose, cellobiose, maltose, trehalose, melibiose, melezitose, xylose (w), galactose (w), rhamnose (w) | mannose, raffinose, cellobiose, maltose, trehalose, melibiose, melezitose, xylose (w), galactose, glucosamine, Naga | sucrose, maltose, trehalose, melezitose, cellobiose, Naga, glucosamine | Naga | Sucrose, maltose, fructose, trehalose, melezitose, Naga, glucosamine |
| Other carbon sources | Glycerol, pyruvate | Glycerol, pyruvate | Glycerol | Glycerol (w) | Glycerol |
| Urea as the N-source*** | + | + | − | + | + |
| Indol from tryptophane (genomic)**** | − | − | + | + | − |
| Salinity range (M total Na+) | 2.5–4.5 (3.5) | 2.5–4.5 (3.5) | 3.0–5.0 (4.0) | 2.5–4.75 (3.5) | 3.0–5.0 (3.5) |
| Minimal Cl− requirement (M) | 2.0 | 1.5 | 1.0 | 1.0 | 1.5 |
| pH range (optimum)***** | 7.1–9.8 (8.5–9.0) | 7.8–9.9 (9.2–9.5) | 7.0–10.0 (9.1–9.3) | 7.2–10.1 (9.5) | 6.5–9.5 (8.0–8.5) |
| Maximum growth temperature (°C) | 50 | 47 | 50 | 45 | 55 |
| General genomic properties | |||||
| Genome size (Mbp) | 4.8 | 5.3 | 4.6 | 4.6 | 3.5 |
| G + C content (%, genomic) | 62.8 | 63.0 | 61.9 | 64.0 | 61.1 |
| GH18 endo-chitinase genes | 3 | 3 | 7 | 11 | 6 |
| GH20 β-N-acetylhexosaminidase genes | 0 | 0 | 1 | 1 | 0 |
| GH3 β-N-acetylhexosaminidase genes | 1 | 1 | 1 | 1 | 1 |
| Isolation source | Hypersaline alkaline lakes, Wadi an Natrun (Egypt) | Hypersaline soda lakes, southwestern Siberia | Soda crystallizer, southwestern Siberia | Hypersaline alkaline Searles Lake, California | |
*The core membrane lipids in type strains are C20-C20 and C20-C25 archaeols with the PG and PGP-Me head groups; **N-acetyl-glucosamine; ***AArcel7 and A-rgal3 genomes encode both urease and urea carboxylase (amydolyase) modules; AArcht7 and AArcht-Sl have only the urea carboxylase operon; ****Presence of tryptophanase TpnA gene; *****actual pH.