Idiosyncratic Fermentation Behaviour of Rhodosporidium toruloides NCIM 3547 in Hemicellulose Hydrolysates derived from Neem Oilseed Cake for Lipid and β-carotene Synthesis

Abstract Neem (Azadirachta indica) Oilseed Cake (NOC) is a by-product of neem seed oil production, acts as a potent second-generation lignocellulosic biomass was employed for integrated production of lipid and β-carotene using Rhodosporidium toruloides NCIM 3547. In this study, a hybrid pretreatment was adopted for the breakdown of lignin and hydrolysis of hemicellulosic compounds resulting in 61.61 (%, w/w) of delignification. The resultant hydrolysate contains both C5, C6 sugars and lignin-degradatory compounds out of which glucose (25.51±1.79 g/L), xylose (10.68±0.19 g/L), arabinose (15.52±0.28 g/L), acetic acid (1.66±0.02 g/L), furfural (126.98±1.41 mg/L) and HMF (259.74±2.89 mg/L). Further, it was subjected to fermentation using Rhodosporidium toruloides NCIM 3547 resulting in 42.53±0.85 (%, w/w) of lipid and β-carotene (60.88±0.39 mg/L; 24.35 μg/g DCW) paved the way for industrial applications. The intracellular lipid bodies were observed by Nile red-stained cells using fluorescent microscopy and its fluorescence intensity was measured by flow cytometer. Subsequently, the lipid was transesterified and the fatty acid profile was analysed using GC-MS to justify its potential for food and biodiesel production. This study reveals that NOC can be utilized for industrial product formation through fermentative strategy by formulating the utilization of lignin and hemicellulosic components towards a circular economy.