2.5. Analytical methods
Total sugars (glucose and xylose) were analyzed by an HPLC
using high performance carbohydrate column (Waters) at 30 °C
with acetonitrile and water mixture (75:25) as a mobile carrier at a
flow rate of 1.4 ml min 1 and detected by a Waters 2414 refractive
index detector. Ethanol in the broth and condensate was analyzed
by a gas chromatograph using Ashco Neon II Gas Analyzer with a
2 m long and 1/8 in. dia Porapak-QS column with mesh range 80/
100. Samples were injected in the gas chromatograph at an inlet temperature of 220°C, oven temperature of 150°C and flame
ionization detector temperature of 250 °C using nitrogen gas as a
carrier.
DCW was determined in the broth by centrifuging 1 ml of broth in pre-dry weighted Eppendorf tube using Eppendorf centrifuge 5415 C at 10,000 rpm for 5 min, followed by washing twice with D/ W and drying in a vacuum oven at 70 °C to a constant weight (Kumar et al. 2015b).