John Castle

Fermentation Engineer

What I Do

I'm an experienced process engineer who has worked with biofuels, recombinant protein, food, beer, and wine manufacturing operations. My career has been primarily in fermentation development at the pilot scale. I specialize in realizing concepts from the drawing board through to physical execution at the pilot scale. I earned my degree in Fermentation Science at Oregon State University and was a guest student in Brewing Science at the Technical University of Munich - Weihenstephan. I have experience with process skid design, equipment sizing and commissioning. I have lead manufacturing lines and established new pilot facilities. Throughout my career I have worked in over 10 different beverage, food and bio-tech facilities (including the world's largest brewery and world's largest winery) and have a wide variety of experience within them.


Who I Am

I was born in Colorado but mostly grew up in Oregon just outside of Portland. As a kid I was very involved in the Boy Scouts and Odyssey of the Mind. During college I moved to Germany for a year as a participant in the Congress-Bundestag Youth Exchange for Young Professionals program. I lived in Köln, Munich and Regensburg. After I finished college I relocated to the Central Valley of California to pursue my career. Soon I found myself living in the Bay Area, exploring all the things that Northern California had to offer. I became involved in cycling and climbing and started spending most of my free time pursuing these hobbies. One thing that has stuck with me through all of my moves has been my interest in photography.




  • Pilot-scale setup and operation of homogenizers, membrane filters, continuous centrifuges/decanters, chromatography mixers, pumps, spray dryers and related instrumentation
  • Familiar with Sartorius 2L, 20L & 300L bioreactors, their installation, operation, maintenance
  • Chromatography Operations: Packing & operating columns up to 40L using ÄKTA Process skid and Unicorn Software
  • SOP and Batchrecord authoring, process flow mapping, P&ID drawing
  • cGMP, GLP, SQF and HACCP protocols
  • ERP/MES systems
  • Forklift Certified

Fermentation Process Development

  • Cell culture of recombinant E. Coli, Pichia pastoris, and Saccharomyces cerevisiae
  • Process development: seedtrain, media, fermentation parameters
  • PAT implementation: offgas, NIR, optical DO, substrate analyzers
  • Downstream Processing: Homogenization, Continuous Centrifugation, Crossflow filtration, Chromatography, Lyophilisation
  • Analytics: Spectroscopy, Total Protein, SDS-PAGE, GC & HPLC methods for fermentation metabolites and product formation

Manufacturing Technology

  • SCADA: Sartorius MFCS/win/S88, Emerson DeltaV
  • MES/Historians: TetraPak PlantManager, OSIsoft PI
  • Utilities: 3-phase power, steam generation, glycol chillers, HVAC, compressed air, low-voltage controls, wastewater management
  • Process equipment sizing: pumps, tanks, fermenters, valves, heat exchangers and chillers
  • Food manufacturing equipment: cookers, centrifuges/decanters, heat exchangers, pumps, grinders, depositors, fillers, printers, labelers, casers, palletizers/wrappers

Professional Experience

Engineer II - Impossible Foods, Inc.

June 2013–Present
  • Lead fermentation engineer developing protein production process in bacterial and yeast host organisms
  • Scratch built fermentation process: seedtrain, media, process conditions, operational decision trees, mass balance models, cost modeling, productivity model, programming for controlling fermentation process
  • Scale 2L process to 1m3, 4m3 and 10m3 tanks in under one year, constantly improving titer & volumetric productivity
  • Contract manufacturing management: sites in US, Canada & Mexico, subject-matter expert, transfer document author, track & report results
  • Develop shakeflask methods for cell bank validation, media development and testing induction parameters
  • Design experiments modeling changes in seedtrain, media, OTR, mixing rates and heat transfer at scale
  • Utilize DoE/Response Surface Methodology using JMP to increase results while minimizing runs
  • Purchase, install, operate and maintain Sartorius fermenters and all related equipment process equipment
  • Own online & offline PAT equipment (DO, pH, offgas, online FT-NIR, offline substrate auto-analyzers)
  • Author fermentation batchrecords, automation, tech transfer documentation, run historian database

Vintage Assistant Winemaker - Pernod Ricard New Zealand

March 2013–May 2013
  • Three month contract position, joined to manage front end production of 40,000t winery
  • Developed SQL database to bring MES, ERP, LIMS and Excel data together, improved reporting over paper system
  • Scheduled presses, issued work orders, liaised between winemaking and viticulture during production irregularities

Production Supervisor - Pacific Foods

January 2012–October 2012
  • Graveyard shift supervisor for 20 operators with varied process experience - scheduling, training, corrective actions
  • Production area produced soup and non-dairy beverage bases to support 35,000 cs/day production
  • Oversaw new staff during commissioning of TetraPak Aseptic Brik A3/Flex Line - UHT/Filler/Caser/Palletizer
  • 8-10 concurrent SKUs per shift base production, 7,000 cs/shift broth packaging on A3/Flex line
  • Supported shift QA with sanitation, quality analysis, audit prep and documentation revision
  • Tracked shift KPIs, completed all leader standard work, ERP data entry and daily lead shift changeover meetings
  • Monitored and evaluated safety, GMPs, and sanitation in production area
  • Participated in ongoing CI initiatives such as 5S, Lean and Autonomous Maintenance

Pilot Plant Associate II - Amyris Biotechnologies

July 2010 - January 2012
  • Developed separation process for hydrocarbon products produced by yeast fermentation
  • Improved recovery via direct experimentation and analysis of prior trials in JMP and Spotfire
  • Operation of 20L and 300L bioreactors: media prep, fermentation, and product recovery
  • Identified changes in fermentation affecting recovery, resulting in process improvements
  • Member of Dept. of Energy grant team testing cellulosic and sorghum feedstocks
  • On-site tech transfer of separation process to CMO at the 200m3 scale

Associate Technologist - E&J Gallo Winery

June 2009 - July 2010
  • Developed and executed process development projects improving winemaking and oak roasting processes
  • Increased column chromatography yields for phenol and ester product recovery
  • Managed harvest projects at the pilot winery (1m3) scale as well as production trials at full scale (200m3)
  • Validated at pilot-scale versions of vendors’ equipment would increase yields, resulting in $1M capital projects
  • Operated all pilot winery equipment, including crossflow filtration, centrifugation, flotation and steam-explosion skids


Oregon State University

Bachelor of Science - Food Science & Technology2009
Option - Fermentation Science
Minor - Chemistry

Technical University of Munich

Guest Student - Brewing & Beverage Technology2008
Participant - Congress-Bundestag Youth Exchange for Young Professionals Program

Internship Experience

Krones AG

  • Developed prediction model for product losses in pasteurization equipment during water push cycles
  • Model used to reduce mix phases caused by water pushes when filler buffer tank fills and UHT goes to water cycle
  • Visited factories within Germany, gathering data, verifying prediction model against the real-world process
  • Assembled UHT skids - learned mix-proof valve assembly, piping, automation wiring, FAT testing procedures


  • Made process modifications and recommendations to improve liquid/solid separation yield (lautering), reduce cycletime and reduce filterpress downtime
  • Modifications resulted in $500,000p/a savings
  • Discovered flaw in vendor’s equipment design and negotiated $250,000 in replacement components at no cost to Coors

Deschutes Brewery

  • Learned all aspects of wort production on 10bbl, 40bbl manual brewhouses; 150bbl automated Huppmann Brewery
  • Learned cellaring, inoculations, centrifugation, filtration
  • Learned QA including CIP verifications, gravity, alcohol, color, bitterness, sensory evaluation

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