Table 2.
Comparative phenotypic and genomic features of ACht6-1, Chv. alkaliphilus, and F. succinogenes.
| Property | Strain ACht6-1 | Chitinivibrio alkaliphilus ACht1 | Fibrobacter succinogenes S85 |
|---|---|---|---|
| Isolation source | Soda lake | Soda lake | Cow rumen |
| pH range for growth (optimum) | 8.5–10.5 (9.5–10) | 8.5–10.6 (9.5–10) | Neutrophilic |
| Salinity range for growth (optimum) | 0.4–1.75 (0.6–1.0) | 0.6–3.5 (1.0–1.5) | Freshwater |
| Optimum growth temperature | 33–35°C | 35–37°C | 37°C |
| Relation to oxygen | Obligate anaerobe | Obligate anaerobe | Obligate anaerobe |
| Cell morphology | Spirillum, polar flagellum, lipid cysts | Vibrio, polar flagellum, intracellular bodies | Nonmotile rods |
| Dominant fatty acids in polar membrane lipids | ai15:0, C14:0, C16:0 | 16:0, C16:1ω7 | 13:0, 13:1, 15:0 |
| Dominant polar lipids | Phosphoglycerol, orhnithine lipid | Phosphatidylglycerol | Phosphatidylethanolamine |
| Genome size (Mb) | 4.4 | 2.6 | 3.8 |
| GC (%) | 42.9 | 46.2 | 48.1 |
| Number of genes | 3827 | 2346 | 3188 |
| Key physiology | Sugar fermentation | Sugar fermentation | Sugar fermentation |
| Growth substrates | Chitin | Chitin | Cellulose, cellobiose, glucose, lactose (weak) |
| Hydrolytic activity (substrates) | Chitin, xylan, starch, carboxymethyl cellulose | Chitin, xylan, carboxymethyl cellulose | Cellulose, xylan, glucomannan, xyloglucan, pectin, inulin, phlein |
| GH families in the genomes | GH 1, 5, 8, 9, 13, 15, 16, 18, 19, 20, 31, 43, 57, 77, 81, 94 | GH 1, 2, 5, 8, 9, 10, 13, 16, 18, 19, 57, 77, 84, 94 | GH 2, 3, 5, 8, 9, 10, 11, 13, 16, 18, 23, 26, 27, 30, 43, 44, 45, 51, 53, 54, 57, 74, 77, 94, 95, 105, 116, 127 |
| Fermentation products | H2, formate, acetate, ethanol, glycerol | H2, formate, acetate, ethanol, lactate, glycerol | Acetate, succinate, formate |
| Glycolytic pathway (s) | EMP | EMP, PP | EMP, PP |
| Tricarboxylic acid (TCA) cycle | Incomplete, lacking succinyl-CoA synthetase | Incomplete, lacking succinate dehydrogenase and succinyl-CoA synthetase | Incomplete, lacking α-ketoglutarate dehydrogenase and succinyl-CoA-synthetase |
| Hydrogenases | Two [Fe–Fe] hydroganases (cytoplasmic) | Two [Fe–Fe] hydroganases (cytoplasmic) | – |
| Electron transport chain | – | – | – |
| Rnf complex | + | + | – |
EMP, Embden–Meyerhof–Parnas; PP, pentose phosphate pathway.