Carbon balance of carbohydrate substrates and products from Caldicellulosiruptor growth on cellulose and unpretreated switchgrass. Carbon balances were as follows: for cellulose, 95.8% ± 13.2% for C. bescii, 92.2% ± 3.9% for C. kronotskyensis, and 96.4% ± 1.5% for C. saccharolyticus; for switchgrass, 95.1% ± 3.4% for C. bescii, 99.3% ± 2.1% for C. kronotskyensis, and 100.7% ± 0.5% for C. saccharolyticus. Values are means ± standard deviations (n = 3).