Engineering Lactococcus cremoris strains co-expressing two cellulase genes for growth on cellulose
Abstract
Lactic acid bacteria are commonly used to convert carbohydrates into valuable products like lactic acid, but they currently rely on carbon sources from food crops, raising sustainability and cost concerns. Lignocellulosic waste is a more sustainable alternative, yet these bacteria cannot naturally break down cellulose to grow on it. Efficient cellulose degradation requires synergetic action of multiple cellulolytic enzymes, each operating through distinct mechanisms. Methods To design genetic constructs for co-expression of gene pairs encoding different heterologous cellulases (Cel5I, Cel5H or Cel9A) from separate expression cassettes in Lactococcus cremoris , the BglBrick approach was used. The activity of culture supernatants containing co-expressed cellulases was assessed on microcrystalline cellulose and phosphoric acid swollen cellulose (PASC), and compared with that of co-cultures and cultures expressing individual enzymes. Subsequently, growth of selected developed strains on PASC was evaluated. Results The A1 strain that co-produced cellulase pair Cel5H-Cel9A achieved the highest activity on PASC and one of the highest activities measured on microcrystalline cellulose. Additionally, the A1 strain showed the highest degradation of PASC during the 16 days of anaerobic cultivation and one of the highest lactic acid production levels. Discussion In this study, co-expression of gene pairs that encode different heterologous cellulases from separate promoters in L. cremoris was achieved for the first time. This approach allows each cellulase to be tuned independently, enabling optimization of their expression levels to maximize synergistic effects and enhance the cellulolytic performance of the engineered bacteria.
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BibTeX
@article{stravs2026engineering,
title = {{Engineering Lactococcus cremoris strains co-expressing two cellulase genes for growth on cellulose}},
author = {Petra Štravs and Henri-Pierre Fierobe and Stéphanie Perret and Aleš Berlec},
journal = {Frontiers in Bioengineering and Biotechnology},
year = {2026},
month = jun,
doi = {10.3389/fbioe.2026.1857763},
url = {https://amu.hal.science/hal-05755120v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Engineering Lactococcus cremoris strains co-expressing two cellulase genes for growth on cellulose
AU - Petra Štravs
AU - Henri-Pierre Fierobe
AU - Stéphanie Perret
AU - Aleš Berlec
PY - 2026
DA - 2026/06/17
JO - Frontiers in Bioengineering and Biotechnology
DO - 10.3389/fbioe.2026.1857763
UR - https://amu.hal.science/hal-05755120v1
AB - Lactic acid bacteria are commonly used to convert carbohydrates into valuable products like lactic acid, but they currently rely on carbon sources from food crops, raising sustainability and cost concerns. Lignocellulosic waste is a more sustainable alternative, yet these bacteria cannot naturally break down cellulose to grow on it. Efficient cellulose degradation requires synergetic action of multiple cellulolytic enzymes, each operating through distinct mechanisms. Methods To design genetic constructs for co-expression of gene pairs encoding different heterologous cellulases (Cel5I, Cel5H or Cel9A) from separate expression cassettes in Lactococcus cremoris , the BglBrick approach was used. The activity of culture supernatants containing co-expressed cellulases was assessed on microcrystalline cellulose and phosphoric acid swollen cellulose (PASC), and compared with that of co-cultures and cultures expressing individual enzymes. Subsequently, growth of selected developed strains on PASC was evaluated. Results The A1 strain that co-produced cellulase pair Cel5H-Cel9A achieved the highest activity on PASC and one of the highest activities measured on microcrystalline cellulose. Additionally, the A1 strain showed the highest degradation of PASC during the 16 days of anaerobic cultivation and one of the highest lactic acid production levels. Discussion In this study, co-expression of gene pairs that encode different heterologous cellulases from separate promoters in L. cremoris was achieved for the first time. This approach allows each cellulase to be tuned independently, enabling optimization of their expression levels to maximize synergistic effects and enhance the cellulolytic performance of the engineered bacteria.
SN - 2296-4185
ER -