Science - USA (2022-04-08)

PHOTOS: (TOP TO BOTTOM VERONICA SZAREJKO; JOHNS HOPKINS PATHOLOGY PHOTOGRAPHY LAB

SCIENCE science.org 8 APRIL 2022 • VOL 376 ISSUE 6589 147

threatened by soil salinity and water scar-

city—stressors that are exacerbated by cli-

mate change. Food security and food waste

are twin crises; more than 800 million peo-

ple are undernourished, and 30% of food

is lost or wasted from farm to fork. Food

waste could potentially feed 1.6 billion

people; instead, it is responsible for 25% of

global freshwater consumption and, when

considered en masse, is the third largest

producer of GHGs after China and the

United States ( 2 , 3 ). New technologies that

are economically sustainable, scalable, and

rapidly deployable to market are needed

to address these challenges. These inno-

vations must also meet stringent require-

ments for safety and biodegradability. The

environmental responsibility of consumers

is increasing, and new laws that limit the

environmental impact of materials are on

the horizon (e.g., the European Union’s

ban on microplastics that begins in 2025).

An opportunity lies for biomaterials to

address these challenges in the agro-food

industry. Our laboratory strives to reinvent

silk as an advanced material to extend food

shelf life, boost crop production, and pre-

cisely deliver payloads in plants ( 4 – 6 ). Silk

is an abundant, natural fiber produced by

Bombyx mori caterpillars when making

their cocoons. Silk fibroin, which is an ed-

ible, nontoxic protein, can be extracted at

low cost from by-products of the textile

industry ( 7 ). This protein is well known

for its mechanical strength, but its struc-

tural polymorphism (i.e., the ability to fold

in stable configurations ranging from a

random coil to a b sheet) is ideal for ap-

plications as a technical material. The

polymorphism of silk fibroin enables its

low-energy, water-based regeneration in

water-soluble or water-insoluble materials,

dependent on molecular structure, and al-

lows for nanomanufacturing in numerous

material formats ( 4 , 7 , 8 ).

Our laboratory has investigated the

self-assembly of regenerated silk fibroin

in transparent coatings that can adhere

to three-dimensional substrates through

spray drying or dip coating, which are

retrofitting tools commonly used in the

agro-food industry ( 9 – 11 ). Modulation of

polymorphism in silk coatings provides ex-

traordinary barrier properties to water and

oxygen as well as resistance to microbial

spoilage and contamination. Payloads such

as bacteria can be encapsulated and pre-

served in these silk coatings, and compos-

ite materials can be easily manufactured

to further tailor coating properties. In the

past few years, research I have contributed

to has led to the spinout of technologies

that use silk-based materials to enhance

food security (see the figure).

We developed safe-to-eat food coatings

using this protein that extend the shelf-life

of perishable foods ( 10 , 12 ). This edible silk

coating can be applied to numerous types

of foods, including produce, meats, fish,

and consumer packaged goods. The coat-

ing decreases evaporation and oxidative

stress and may contribute to a reduction

in natural microbial spoilage. In 2018, the

technology spun out to a company called

Mori (formerly Cambridge Crops, Inc.),

which uses intellectual property (IP) devel-

oped with my research. Mori was also rec-

ognized as a 2021 World Economic Forum

Technology Pioneer. Since its founding,

Mori has raised upward of $88 million and

currently employs more than 55 people

in offices across the United States and in

Mexico. The food coating is designated as

“generally recognized as safe” in the United

States and has obtained “non-novel” food

status from Health Canada. Silk fibroin is

also considered safe to eat in other coun-

tries based on the historic consumption of

B. mori in those countries. Mori can scale

up this technology and intends to continue

using it to extend shelf life and build a

more resilient food supply.

In addition, our laboratory has also de-

veloped a silk-based seed-coating technol-

ogy for the delivery of plant growth–pro-

moting rhizobacteria (PGPRs). PGPRs boost

plant health and crop yield by increasing

the availability of macronutrients, decreas-

ing the use of synthetic fertilizers and pesti-

cides, and mitigating abiotic stressors ( 13 ).

The use of PGPRs is frequently hindered by

limited viability outside the soil and dur-

ing desiccation. By using a combination of

rational design and bioinspiration, silk and

polysaccharides are combined to adhere to

a seed surface, encapsulate and preserve

bacteria in a dry state, and modulate their

delivery and growth in the spermosphere

( 14 ). In field tests conducted at an experi-

mental farm in Ben Guerir, Morocco, in col-

laboration with Mohammed VI Polytechnic

University, the delivery of PGPRs through

seed coatings boosted growth when plants

were grown in saline soil and under water-

stress conditions (see the figure) ( 15 ). A

technology spinout effort is underway to

commercialize these coatings and have a

positive impact on our society by mitigating

climate and food crises.

Together, these technologies open the

door to the application of biomaterials to

boost food security and enhance agro-food

resilience. We are bringing innovation to a

field that needs creative solutions to enhance

food production while minimizing inputs

and mitigating environmental impacts. j

REFERENCES AND NOTES

1. National Academy of Engineering (NAE), NAE grand
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2. H. C. J. Godfray et al., Science 327 , 812 (2010).


3. Food and Agriculture Organization of the United
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   in the world” (FAO, 2019); http://www.fao.org/3/ca5162en/
   ca5162en.pdf.


4. H. Sun, B. Marelli, MRS Commun. 11 , 31 (2021).


5. D. Kim et al., Adv. Funct. Mater. 31 , 2005370 (2021).


6. Y. Cao, E. Lim, M. Xu, J.-K. Weng, B. Marelli, Adv. Sci. 7 ,
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7. B. Marelli et al., Proc. Natl. Acad. Sci. U.S.A. 114 , 451
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8. Z. Zhou et al., Adv. Mater. 30 , 1706983 (2018).


9. H. Sun, B. Marelli, Nat. Commun. 11 , 351 (2020).


10. B. Marelli, M. A. Brenckle, D. L. Kaplan, F. G. Omenetto,
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11. E. Ruggeri et al., ACS Sustain. Chem. Eng. 8 , 14312
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12. S. Yigit et al., Food Chem. Toxicol. 151 , 112117 (2021).


13. A. T. Zvinavashe, E. Lim, H. Sun, B. Marelli, Proc. Natl.
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14. A. T. Zvinavashe, I. Mardad, M. Mhada, L. Kouisni, B.
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15. A. T. Zvinavashe et al., Nat. Food 2 , 485 (2021).

10.1126/science.abo4233

Department of Civil and Environmental Engineering,

Massachusetts Institute of Technology, Cambridge, MA,

USA. Email: [email protected]

FINALIST

Philipp Mews

Philipp Mews re-

ceived an under-

graduate degree

from the Free Uni-

versity of Berlin and

a BSc and PhD from

the University of

Pennsylvania. In 2017 he cofounded

EpiVario, Inc., and is currently an in-

structor in the Neuroscience Depart-

ment at the Icahn School of Medicine

at Mount Sinai. His research explores

the interplay between metabolism

and epigenetics in the adult brain,

with an emphasis on brain circuits

involved in the formation and main-

tenance of memory. http://www.science.org/

doi/10.1126/science.abo4234

FINALIST

Jacqueline Douglass

Jacqueline Douglass

received her under-

graduate degree

from the Massa-

chusetts Institute

of Technology and

an MD-PhD from

Johns Hopkins University School

of Medicine. She is currently an

internal medicine resident at Johns

Hopkins and plans to pursue medical

oncology training. http://www.science.org/

doi/10.1126/science.abo4237

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