Marimuthu Anandharaj, Yu-Ju Lin, Rizwana Parveen Rani, Eswar Kumar Nadendla, Meng-Chiao Ho, Chieh-Chen Huang, Jan-Fang Cheng, Jui-Jen Chang, and Wen-Hsiung Li* (2020) Constructing a yeast to express the largest cellulosome complex on the cell surface Proceedings of the National Academy of Sciences of the United States of America, 2020, 201916529; DOI: 10.1073/pnas.1916529117
Sustainable utilization of cellulosic biomasses to produce valuable compounds is an ideal approach but hydrolysis of recalcitrant cellulose is complex and time-consuming. Several cellulolytic bacteria produced multi-enzyme complexes called ‘cellulosomes’ that efficiently degrade the cellulose. Hence, we engineered the yeast Kluyveromyces marxianus to express the ‘largest cellulolytic complex’, which can accommodate up to 63 enzymes, on its cell-surface. To achieve this, we have engineered the cellulosomal genes including Scaffoldin protein (CipA), anchoring protein (OlpB) and cellulolytic enzymes into K. marxianus genome. The engineered yeast host efficiently degraded cellulosic substrates and released 3.09 g/L and 8.61 g/L of ethanol from avicel and phosphoric acid swollen cellulose (PASC), respectively, which are higher than any previously constructed yeast cellulosome. In future, this superb cellulosome complex may also be used for the synthesis of various biopharmaceutical products (e.g., astaxanthin and morphine), which involve multiple enzymatic conversion steps.