Science at the Edge Seminar

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Speaker:  José Avalos, Center for Energy and the Environment and Department of Chemical & Biological Engineering, Princeton University

Title: Spatial and Temporal Control of Yeast Isobutanol Production with Subcellular Engineering and Optogenetics

Refreshments at 11:15 am.

Date: Fri, 21 Sep 2018, 11:30 am – 12:30 pm
Type: Seminar
Location: 1400 BPS Bldg.

Abstract:
Subcellular localization and dynamic control of metabolic path­ways have received much atten­tion in meta­bolic engineering in recent years. Each sub­cellular compart­ment in yeast offers a unique physico­chemical environ­ment as well as dis­tinct metabo­lite, enzyme, and co­factor composi­tions, which may bene­fit the activ­ity of meta­bolic path­ways. Further­more, the spatial separa­tion of organ­elles from cytosol offers unique oppor­tunities to reduce the toxic­ity of inter­mediates, eliminate meta­bolic cross­talk, and enhance the efficiency of compart­mentalized path­ways. In the first part of my talk I will show how interest­ing and unex­pected behaviors arise when organelles are in­volved in meta­bolic path­ways, and present new data on how com­part­men­talizing the Ehr­lich path­way in yeast mito­chondria boosts iso­butanol produc­tion.

In the second part of my talk I will show how opto­genetics can be applied to meta­bolic engineering. Meta­bolic path­way opti­miza­tion re­quires fine-tuning the timing and levels of expres­sion of meta­bolic en­zymes. Opto­genetic con­trols are ideal for this, as light can be applied and removed instant­ly with­out com­plex media changes. I will pre­sent a new tech­nological plat­form that uti­lizes a light-sensi­tive transcrip­tion fac­tor to achieve un­prece­dented con­trol over engineered meta­bolic path­ways in yeast. Using this tech­nology, we achieve ro­bust and homo­geneous transcrip­tional con­trol at cell den­sities as high as 50 OD600 in 5L bioreactors. I will show how opto­genetics enables a new mode of bio­reactor opera­tion, in which periodic light pulses are used to tune the levels and timing of enzyme expression during the fermenta­tion to boost yields.

Combining mito­chondrial engineering with dynamic regula­tion of meta­bolic path­ways allows us to pro­duce up to 8.49 ± 0.31 g/L of iso­butanol and 2.38 ± g/L of 2-methyl-1-bu­tanol micro-aero­bical­ly from glu­cose in lab-scale bio­reactors, which is more than a 10-fold improve­ment over strains lack­ing opto­genetic con­trols. These results make a compel­ling case for the applica­tion of sub­cellular engineering and opto­genetics to meta­bolic engineering to develop not only new strate­gies for meta­bolic path­way opti­miza­tion, but also new capa­bilities for operating, optimizing, and auto­mating bio­reactors.

Speaker Bio:
José Avalos is an Assistant Professor in the Depart­ment of Chemical and Bio­logical Engineering, and the Andlinger Center for Energy and the Environ­ment at Prince­ton Univer­sity. He is also an asso­ciated faculty member in the Depart­ment of Molecular Biology. He received his PhD from Johns Hopkins Univer­sity in Bio­chemistry and Bio­physics, and com­pleted post­doctoral research in the Depart­ment of Chemical Engineering at MIT, The White­head Insti­tute, and The Rocke­feller Univer­sity. His fields of research in­clude syn­thetic biology, meta­bolic en­gineering, protein en­gineering, sys­tems biology and struc­tural bio­logy. He has been honored with the NSF CAREER award, The Alfred P. Sloan Founda­tion Fellow­ship Award, and The Pew Scholar­ship, among other awards.