White biotechnology and enzymes

18 11 2011

For tens of thousands of years, humans relied on nature to provide them with everything they needed to make their lives more comfortable -cotton and wool for clothes, wood for furniture, clay and ceramic for storage containers, even plants for medicines. But this all changed during the first half of the twentieth century, when organic chemistry developed methods to create many of these products from oil.  Oil-derived synthetic polymers, colored with artificial dyes, soon replaced their precursors from the natural world.

But today, with growing concerns about the dependence on imported oil and the awareness that the world’s oil supplies are not limitless, coupled with stricter environmental regulations,  chemical and biotechnology industries are exploring nature’s richness in search of methods to replace petroleum-based synthetics.  As with other forms of biotechnology, industrial biotech involves engineering biological molecules and microbes with desirable new properties. What is different is how they are then used: to replace chemical processes with biological ones. Whether this is to produce chemicals for other processes or to create products such as biopolymers with new properties, there is a  huge effort to harness biology to accomplish what previously needed big, dirty chemical factories, but in cleaner and greener ways.

The public has for a long time perceived biotechnology to mean dangerous meddling with the genes in food and fiber crops.  But biotechnology is about much more than transgenic crops – it also uses microbes to make pharmaceuticals, for example.  Industrial biotechnology is known as “white” biotechnology, as distinct from “red” biotechnology, which is devoted to medical and pharmaceutical purposes, and “green” biotechnology, or the application of biotechnology in agriculture.

From: EuropaBio

Today, the application of biotechnology to industrial processes holds many promises for sustainable development.  One of the first goals on white biotechnology’s agenda has been the production of biodegradable plastics, and in textiles,  DuPont has invested much in the production of textile fibers from corn sugar (Sorona ®) while Cargill Dow has introduced NatureWorks ™, a polymer made from lactic acid which is used in textiles under the brand name Ingeo ®.  And these new processes have resulted in considerable environmental benefits:  In the case of Sorona ®, for example,  DuPont was able to replace the toxic elements of ethylene glycol and carbon monoxide in typical PET fibers with benign corn sugars.

But there are challenges pertaining to these new bioplastics, and the evidence that they’re actually better for the planet is hotly debated.  As Jim Thomas argues in the New Internationalist online magazine:

Strictly speaking a bioplastic is a polymer that has been produced from a plant instead of from petroleum. That is neither a new breakthrough nor a guarantee of ecological soundness. The earliest plastics such as celluloid were made from tree cellulose before petroleum proved itself a cheaper source. Today, with oil prices skyrocketing, it’s cheaper feedstock –  not green principles –  that is driving chemical companies back to bio-based plastics. Bioplastics may bring in the greenbacks for investors but are they actually green for the planet? The evidence is not convincing. For a start bioplastics may or may not be degradable or biodegradable – two terms that mean very different things. Many bio-based plastics – like DuPont’s Sorona – make no claims to break down in the environment. So much for disposal. But replacing fossil fuels with plants has to be a good idea, right? This is the premise on which the green claims of bioplastics mostly rest. Unfortunately, as advocates of biofuels have learned, switching from oil to biomass as the feedstock of our industrial economy carries its own set of problems. Like hunger.

There is nothing sustainable or organic about most industrial agriculture feedstocks. At present genetically modified corn grown using pesticides is probably the leading source of starch for bioplastics.  The link between genetic contamination and bioplastics is strong.

As concerns mount, the Sustainable Biomaterials Collaborative (SBC) – a network of 16 civil society groups and ethical businesses – is working to define a truly sustainable bioplastic. One of its founders, Tom Lent, explains that the SBC started because ‘the promise of bioplastics was not being realized’.

But biotechnology is not just about bioplastics – it’s actually mostly, these days,  about enzymes.  Biotechnology can provide an unlimited and pure source of enzymes as an alternative to the harsh chemicals traditionally used in industry for accelerating chemical reactions. Enzymes are found in naturally occurring microorganisms, such as bacteria, fungi, and yeast, all of which may or may not be genetically modified.  (We’ll come back to this important point later.)

But what are enzymes?

Enzymes are large protein molecules that  act as  catalysts – substances that start or accelerate chemical reactions without themselves being affected —  and help complex reactions occur everywhere in life.  By their mere presence, and without being consumed in the process, enzymes can speed up chemical processes – reactions occur about a million times faster than they would in the absence of an enzyme. In principle, these reactions could go on forever, but in practice most enzymes have a limited life.   There are many factors that can regulate enzyme activity, including temperature, activators, pH levels, and inhibitors.

Enzymes play a diversified role in many aspects of everyday life including aiding in digestion and the production of food as well as in industrial applications. Enzymes are nature’s catalysts. Humankind has used them for thousands of years to carry out important chemical reactions for making products such as cheese, beer, and wine. Bread and yogurt also owe their flavor and texture to a range of enzyme producing organisms that were domesticated many years ago.

Enzymes are categorized according to the compounds they act upon. Some of the most common include:

  •  proteases which break down proteins,
  •  cellulases which break down cellulose,
  •  lipases which split fats (lipids) into glycerol and fatty acids, and
  •  amylases which break down starch into simple sugars.  Human saliva, for example, contains amylase, an enzyme that helps break down starchy foods into sugars.

In textile treatment, the first enzyme applications, as early as 1857, was the use of barley for removal of starchy size from woven fabrics. The first microbial amylases were used in the 1950s for the same desizing process, which today is routinely used by the industry.

Enzymes are now widely used to prepare the fabrics that your clothing, furniture and other household items are made of.  Increasing demands to reduce pollution caused by the textile industry has fueled biotechnological advances that have replaced harsh chemicals with enzymes in many textile manufacturing processes.  The use of enzymes not only make the process less toxic (by substituting enzymatic treatments for harmful chemical treatments) and eco-friendly, they reduce costs associated with the production process, and consumption of natural resources (water, electricity, fuels), while also improving the quality of the final textile product.

But how do they work?

Rader’s Chem4Kids.com website  has a great explanation, which I’ve quoted below:

Think of enzymes as similar to keys which can open locks.  Just as when you need a key that is just the right shape to fit in a particular lock, enzymes complete very specific jobs and do nothing else.  

From: Chem4Kids

 They are very specific locks and the compounds they work with are the special keys. In the same way there are door keys, car keys, and bike-lock keys, there are enzymes for neural cells, intestinal cells, and your saliva.

Here’s the deal: there are four steps in the process of an enzyme working. 

  1.  An enzyme and a substrate are in the same area. The substrate is the biological molecule that the enzyme will attack. 
  2.  The enzyme grabs onto the substrate with a special area called the active site.  The active site is a specially shaped area of the enzyme that fits around the substrate. The active site is the keyhole of the lock. 
  3. A process called catalysis happens. Catalysis is when the substrate is changed. It could be broken down or combined with another molecule to make something new. 
  4.  Then the enzyme lets go.  When the enzyme lets go, it returns to normal, ready to do another reaction. But the substrate is no longer the same – the substrate is now called the product.

Next, well take a look at how enzymes are helping to make the textile industry’s environmental footprint a bit more benign.