Ipid concentration and decreased the lipid yield. Maximal lipid yield of
Ipid concentration and decreased the lipid yield. Maximal lipid yield of 92.1 mg g-1 (corresponds to 32.72 of theoretical lipid yield) was obtained with concentration of 12.5 g L-1 was -1 obtained at substrate loading of 20.0 (g g-1 ), when lipid substrate loading of 12.5 (g1 g ). Enhanced substrate loading is usually a frequent Zabofloxacin Epigenetic Reader Domain tactic ap- ). Similarly, Liu et al. (2012) observed a 30 increase of lipid yield decreased to 0.62 (g g plied in producing lignocellulosic biofuels to improve the item yield. A related effect concentration in SSF with yeast Trichosporon cutaneum when substrate loading (pretreated of high-substrate loading on enzyme hydrolysis of pretreated rapeseed straw and solution corn stover) was improved from 10 to 15 (g g-1 ) [38]. accumulation has been observed in bioethanol production [36]. A rise of substrate loading up to 20 (g g-1) positively affected solution end concentration. On the other hand, the maximal bioethanol yield (g of product g-1 of the substrate) and bioethanol productivity was obtained at substrate loading of 15 (g g-1). Dai et al. (2019) studied the impact of substrate loading (one hundred , g g-1) on lipid production utilizing yeast Rhodosporidium toruloides inJ. Fungi 2021, 7,9 ofTable two. Impact of substrate loading (five.00.0 , g g-1 ) on lipid production in batch SSF at low enzyme loading (five FPU g-1 glucan). Cultivation B_1 B_2 B_3 B_4 B_5 B_6 Substrate ( , g g-1 ) 5.0 7.5 10.0 12.5 15.0 20.0 Time (d) three 6 10 10 ten 10 wL ( , g g-1 ) 9.10 0.76 13.36 0.60 20.98 0.66 14.37 0.24 14.50 0.43 9.27 0.17 L (g L-1 ) 2.99 0.61 5.56 0.61 7.47 0.58 12.00 0.48 12.02 0.87 12.52 0.52 YL/S (mg g-1 ) 59.72 74.07 74.7 92.1 80.1 62.six PrL (g L-1 d-1 ) 0.99 0.93 0.75 0.88 1.20 1.25 L 21.23 26.33 26.55 32.72 28.47 22.wL , lipid content in strong residue; L, lipid concentration; YL/S , lipid yield on pretreated lignocellulosic biomass; PrL , maximal lipid productivity; L , lipid recovery on pretreated lignocellulosic biomass (calculated according to Ivancic Santek et al. [17]).three.three. Fed-Batch SSF at a Low Enzyme Loading The fed-batch technique in SSF enables overcoming the concerns with irregular mixing, low mass transfer of enzyme and substrate, and low solution yield characteristic for batch cultivation at high-substrate loading [35,39]. Fed-batch cultivations were performed at 15 and 20 substrate loading working with two feeding approaches to improve the lipid yield. Low initial substrate loading (five , g g-1 ) and sequential addition of substrate at 2.5 and five (g g-1 ) for the duration of cultivation enabled to overcome complications with higher viscosity of culture media previously observed in batch SSF and enabled extra efficient mixing and mass transfer. Two substrate additions at five (g g-1 ; FB_1 culture) and six additions at 2.five (g g-1 ; culture FB_2) resulted in accumulative substrate loading of 15 and 20 (g g-1 ), respectively. The total enzyme amount (five FPU g-1 glucan) calculated on cumulative substrate loading was supplied at the starting in the prehydrolysis step. Just after a brief prehydrolysis step, the lignocellulosic slurry was inoculated with yeast. A related tactic of feeding and early addition of a total volume of cellulases (based on cumulative substrate loading) was successfully applied within the production of bioethanol from waste paper, rising the yield of ethanol (11.six , v v-1 ) and cumulative substrate loading (65 , g g-1 ) [40]. The time for substrate additions depended around the viscosity in the culture broth, which was estimated by visual.