TABLE 2.
Growth of F. johnsoniae on various carbohydrates
| Substratea | Substrate type | Relative growth rateb |
|---|---|---|
| d-Glucose | Monosaccharide | 1.0 (0.2) |
| d-Fructose | Monosaccharide | 0.9 (0.1) |
| d-Galactose | Monosaccharide | 0.7 (0.1) |
| d-Mannose | Monosaccharide | ± |
| d-Xylose | Monosaccharide | 1.2 (0.2) |
| d-Galacturonic acid | Monosaccharide | 0.5 (0.1) |
| d-Glucosamine | Monosaccharide | 0.6 (0.1) |
| N-Acetylglucosamine | Monosaccharide | ± |
| Cellobiose | Disaccharide | 1.0 (0.1) |
| Cellohexaose | Hexasaccharide | ± |
| Pullulan | Linear water-soluble polymer of glucose with α-1,4 and α-1,6 glycosidic bonds | 0.6 (0.1) |
| Laminarin (brown algae) | Linear polymer of glucose with β-1,3 and β-1,6 glycosidic bonds | 1.3 (0.1) |
| Amylopectin (potato) | Insoluble component of plant starch; branched polymer of glucose with α-1,4 and α-1,6 glycosidic bonds | + |
| Dextran (from L. mesenteroides) | Branched polymer of glucose with primarily α-1,6 and α-1,4 glycosidic bonds | 0.8 (0.1) |
| Polygalacturonate (citrus peel) | Pectic polysaccharide | 1.5 (0.1) |
| Arabinoxylan (wheat) | Hemicellulosic polysaccharide | + |
| β-Glucan (barley) | Hemicellulosic polysaccharide | + |
| Methyl glucuronyl xylan | Hemicellulosic polysaccharide | ± |
| Xylan (oat spelt, water-soluble fraction) | Hemicellulosic polysaccharide | 0.7 (0.1) |
| Xyloglucan (tamarind) | Hemicellulosic polysaccharide | 0.8 (0.1) |
| Galactomannan (carob) | Hemicellulosic polysaccharide | 1.2 (0.1) |
| Glucomannan (konjac) | Hemicellulosic polysaccharide | 1.9 (0.4) |
All carbohydrates were used at a concentration of 5 mg ml−1 in SD minimal medium, except for rhamnogalacturonan I, which was used at a concentration of 10 mg ml−1. The following carbohydrates did not support growth: d-arabinose, l-fucose, ribose, d-glucuronic acid, N-acetylgalactosamine, l-rhamnose, sucrose, lactose, carboxymethyl cellulose, α-mannan (Saccharomyces cerevisiae), α-arabinan (sugar beet), arabinogalactan (larch), inulin (chicory), β-1,4-galactan (potato and lupin), λ-carrageenan (seaweed), levan (Erwinia herbicola), rhamnogalacturonan I (potato pectin), RNA, DNA (salmon sperm), and xanthan gum. The sources of some of the polysaccharides are indicated in parentheses.
Relative growth rates were determined by dividing the doubling time (in min) in SD medium plus glucose by the doubling time in SD plus the test substrate. Thus, a relative growth rate greater than 1 for a substrate indicates that growth on the substrate was more rapid than growth on glucose. Each substrate was tested in quadruplicate, and standard deviations are indicated in parentheses. ±, cells grew too slowly to calculate the relative growth rate, but the optical density at 600 nm was at least 0.1 after 88 h of incubation; +, cells grew on the substrate, but the growth rate could not be determined accurately due to the high turbidity of the initial growth medium containing the insoluble polysaccharide.