TY - JOUR
T1 - High-Level fermentative production of Lactic acid from bread waste under Non-sterile conditions with a circular biorefining approach and zero waste discharge
AU - Cox, Rylan
AU - Narisetty, Vivek
AU - Nagarajan, Sanjay
AU - Agrawal, Deepti
AU - Ranade, Vivek V.
AU - Salonitis, Konstantinos
AU - Venus, Joachim
AU - Kumar, Vinod
N1 - Publisher Copyright:
© 2021
PY - 2022/4/1
Y1 - 2022/4/1
N2 - Bread waste (BW) is a severe solid waste management problem in Europe. The current study demonstrates an environment-friendly solution by valorising BW into lactic acid (LA) and the corresponding solid residues generated during hydrolysis and fermentation to biogas. To this end, BW was saccharified through acidic and enzymatic hydrolysis, and the hydrolysate obtained was used for LA fermentation under non-sterile conditions using thermophilic Bacillus coagulans DSM1. Maximum glucose concentration achieved during acid hydrolysis with 2% (v/v) acid loading and 20% (w/v) solid loading was 67.9 g/L glucose, with a yield of 0.34 g/g BW. The LA accumulated with concentrated BW acid hydrolysate was 102.4 g/L with yield and productivity of 0.75 g/g and 1.42 g/L. h, respectively. For enzymatic hydrolysis, three commercial amylase preparations (Amyloglucosidase, Spirizyme, Dextrozyme) were employed. The highest glucose release (98.6 g/L) and yield (0.49 g glucose/g BW) was attained with Dextrozyme from Novozymes. The fed-batch fermentation by B. coagulans was conducted, using commercial glucose and glucose-rich BW hydrolysate from Dextrozyme. The LA titer, yield and productivity obtained with pure glucose were 222.7 g/L, 0.92 g/g and 1.86 g/L.h, respectively, whereas BW hydrolysate (BWH) resulted in 155.4 g/L LA, with a conversion yield and productivity of 0.85 g/g glucose and 1.30 g/L. h, respectively. Further to the LA biosynthesis, the solid residues generated during hydrolysis and fermentation were subjected to biogas generation, resulting in 553 mL CH4/g volatile solids under batch mode. This massive LA titer amassed under non-sterile conditions and integrated biogas production using fermented residues demonstrates a high potential for an integrated biorefinery based on BW.
AB - Bread waste (BW) is a severe solid waste management problem in Europe. The current study demonstrates an environment-friendly solution by valorising BW into lactic acid (LA) and the corresponding solid residues generated during hydrolysis and fermentation to biogas. To this end, BW was saccharified through acidic and enzymatic hydrolysis, and the hydrolysate obtained was used for LA fermentation under non-sterile conditions using thermophilic Bacillus coagulans DSM1. Maximum glucose concentration achieved during acid hydrolysis with 2% (v/v) acid loading and 20% (w/v) solid loading was 67.9 g/L glucose, with a yield of 0.34 g/g BW. The LA accumulated with concentrated BW acid hydrolysate was 102.4 g/L with yield and productivity of 0.75 g/g and 1.42 g/L. h, respectively. For enzymatic hydrolysis, three commercial amylase preparations (Amyloglucosidase, Spirizyme, Dextrozyme) were employed. The highest glucose release (98.6 g/L) and yield (0.49 g glucose/g BW) was attained with Dextrozyme from Novozymes. The fed-batch fermentation by B. coagulans was conducted, using commercial glucose and glucose-rich BW hydrolysate from Dextrozyme. The LA titer, yield and productivity obtained with pure glucose were 222.7 g/L, 0.92 g/g and 1.86 g/L.h, respectively, whereas BW hydrolysate (BWH) resulted in 155.4 g/L LA, with a conversion yield and productivity of 0.85 g/g glucose and 1.30 g/L. h, respectively. Further to the LA biosynthesis, the solid residues generated during hydrolysis and fermentation were subjected to biogas generation, resulting in 553 mL CH4/g volatile solids under batch mode. This massive LA titer amassed under non-sterile conditions and integrated biogas production using fermented residues demonstrates a high potential for an integrated biorefinery based on BW.
KW - Acidic/Enzymatic hydrolysis
KW - Bacillus coagulans
KW - Biochemical methanation potential
KW - Bread waste
KW - Lactic acid
KW - Non-sterile conditions
UR - http://www.scopus.com/inward/record.url?scp=85122318290&partnerID=8YFLogxK
U2 - 10.1016/j.fuel.2021.122976
DO - 10.1016/j.fuel.2021.122976
M3 - Article
AN - SCOPUS:85122318290
SN - 0016-2361
VL - 313
JO - Fuel
JF - Fuel
M1 - 122976
ER -