One of the most sustainable raw materials for chemicals and materials is organic waste. Energy has already been spent producing it, making it far more resource-efficient than any grown or extracted specifically for a target application.
The EU wants more of its bioeconomy to be based on the raw materials of waste rather than virgin feedstock but so far only 22.7% of its bio-products comes from byproducts. The small portion of waste utilised in the EU bioeconomy is also mainly targeted at bioenergy rather than chemicals and materials.
Waste feedstock is cheap and abundant. So why does it remain unpopular? The main obstacle is its uneven quality and chemical makeup, making it difficult to form a consistent product from it.
One way to solve this is to modify bacteria so that they are able to metabolise these wastes and concentrate their useful elements efficiently. Thanks to their complex biological mechanisms, microorganisms can metabolise different compounds into single products far more effectively than purely chemical technologies.
The problem then becomes one of mastering the biotechnological tools for gene modification so as to custom grow strains with optimal ability to work quickly in transforming the waste.
New advances in microbial engineering are opening up formerly inefficient wastes to become feedstock for the bioeconomy and these custom-modified bacteria are a new way of making useful material from unconventional feedstock.
Microbial colour for textiles
Conventional synthetic pigments draw on chromium and heavy metals. Biopigments are garnering a lot of interest for being non-toxic, biodegradable, and non-carcinogenic alternatives.
Microbial biopigments have advantages over plant and animal sources due to their fast growth, the fact they are available all year round, and the ability to adjust the productivity of microbes. They also cut the energy and water consumption of conventional dying techniques.
One of the biggest demand sectors for biopigments is the fashion industry. By now, consumers are aware of the severe toll that apparel manufacturing has on the environment. Demand for low-impact clothing inputs from designers and retailers will grow – particularly where the alternatives are cost-effective.
Right now, the most expensive part of manufacturing biopigments is the cost of the bacterial substrate, the ‘feed’ that sustains microbes. Often, these are made from synthetic sources too. But one way to keep costs low here is to use agro-industrial wastes. Using agricultural waste for biotech has dual benefits for the environment: it clears dumped waste from ecosystems while replacing synthetic chemicals in biobased products.
India accounts for the generation of 350 million tonnes of agro-waste generated every year, making it the ideal hub for a circular economy based around microbes and farming byproducts. It also has a huge textile industry. This confluence means Indian biotech startup KBCols Sciences has been one of the leaders in microbial agro-waste dyes for the textile industry.
KBCols started out producing just 10 grams of dye in small flasks in 2018-2019. Now, they are at the industrial pilot phase producing blue, brown, green, and pink, which can be mixed to produce secondary colours. The R&D team are now working on orange, yellow, and red.
Its drop-in powder products are meant for both natural and synthetic fibres and the microbes used to grow the dye are sourced from the soils, waters, and airs of India. The agricultural waste is placed in the bioreactors where microbes grow and the company is in talks with farmer groups to enlarge their feedstock pool.
The company is currently testing their dyes with international apparel and luxury brands across the world. Most are confidential for now but two of the public names are Albini Group in Italy, which is supported in the pilot process by luxury brand Kering Group, and Shahi Exports, a leading apparel exporter in India. The company wants to extend their dyes out from the textile industry to cosmetics and food by 2028.
Alternative proteins
Would you eat protein made from waste? Dutch startup Afterlife have managed to create a flavour-neutral vegan protein made from food thrown away from restaurants. Fungi are the microorganisms at work here turning the discard into healthy, land-efficient alternatives to animal protein. There are a huge number of non-animal proteins on the market today but few are using waste to achieve a convincing meat substitute.
“Through Fungal fermentation technology, we unlock the power of these overlooked resources, creating a sustainable protein ingredient that is both functional and delicious,” according to the company.
Afterlife is also filling the niche left by consumers abandoning plant-based products after the pandemic boom in this industry. Additives were among the number one concerns about these plant-based proteins and Afterlife’s mycoproteins eliminates these, leaving a neutral, flavour-absorbing base which appeal to health-conscious consumers.
Afterlife also claims their product has some of the functional properties that many plant-based alternatives to meat lack – these are the ways that the chemicals inside the protein react to heat and oils which can impact flavour and texture after the cooking process. While animal meats are rich in fibrous textures and fatty compounds that give it their characteristic taste and mouthfeel, it has so far been difficult to replicate these properties using basic plant substudies.
Zayt is another microbial protein startup targeting the problem area of making plant proteins replicate the chemical behaviours of animal proteins during cooking. Founded by Amr Aswad and Venkat Konasani, it uses precision fermentation technology to valorise wasted fruit into non-meat fats. The name ‘Zayt’ comes from the Arabic word for ‘oil’.
The startup has come up with a plant butter that looks, feels, and cooks like ordinary dairy butter. It aims to start fulfilling orders by the end of 2024 through a partnership with German company Kynda.
There are already popular plant-based fats on the market such as palm and soy but these crops are contributing to global deforestation. Using waste takes the pressure off the land and uses resources that do not add to emissions and biodiversity loss.
Animal food
Reducing meat consumption is one of the most effective ways to cut global carbon emissions and habitat loss. One of the reasons that meat production is so harmful is that the animal feed comes from the expansion of vast feed crop plantations that replaced biodiverse habitats.
However, as long as livestock farming remains a huge employer worldwide it remains imperative to cut down the emissions and ecological costs of animal feed where possible. Here, microbial transformations can help.
Already, agro-industrial wastes from cereals (barley, corn, oats, millet, and sorghum) are produced in large quantities to feed animals. However, these conventional waste feeds contain low levels of minerals, vitamins, fats, and proteins and do not efficiently meet the nutritional needs of animals. Using microbial biotechnology, these low value feeds can be enhanced because certain species can reduce the bioactive compounds that interfere with nutrient bioavailability and digestibility.
MicroHarvest are taking sugar and food waste streams and feeding them to their bacterial strains, which then grow exponentially, providing an all-year-round harvest of between 60-70% crude protein for the animal feed markets. It is starting by targeting aquaculture and livestock but has plans to move into pet and human protein food in the years to come.
The waste-microbe animal feed industry has not realised its full potential. There are many studies showing the health and nutritional benefits of using microbes to concentrate nutrients inside agro waste streams using bacterial strains. Scientists have explored many waste product combinations that have not yet been tapped commercially.
In one study, researchers fed broiler chickens for 35 days with 10% wheat bran fermented with Bacillus amyloliquefaciens and Saccharomyces cerevisiae, and reported improvement in the health status as well as improved intestinal microbiota. A similar study by Jazi et al showed that the use of fermented cotton seed meal significantly improved the growth performance and intestinal health of broiler chickens. The possibilities here are endless and many strain-waste combinations are waiting to be tapped.
Industrial enzymes
Enzymes are biological catalysts that find applications in several industries that range from baking and brewing to paper, pulp and the detergent industry. They are relatively expensive substances to make, adding to the cost of processes that use them. Almost 50% of the cost of production is associated with capital investment with raw materials, almost one third of this.
Turning cheap agro-waste into high quality industrial enzymes using microbes is one way to lower the costs of enzyme-based industrial processes. Indian company IT-Madras team deploys the Bacillus sp PM06, a bacteria isolated from sugar cane waste to break down usually recalcitrant agro-wastes known as lignocellulosic wastes and produce industrial enzymes alpha-amylase, cellulase enzymes, ethanol and acetic acid.
Usually, lots of enzymes are needed to break down this low value waste to access the chemicals locked up in them. This is a costly process. With IT-Madras’ modified bacteria, the process becomes easier, drawing on just one biological agent rather than several in a complex series of steps. Its yields were also produced, which are useful in various industries.
As well as its proprietary micro-organisms, the company’s most valuable asset is its novel solid state fermentation (SSF) bioreactor custom-designed for their microbial transformation.
Fermentech is another Indian company turning agro-waste into four enzymes: pectinase (used by the fruit juice, wineries, textile, aquaculture industries), amylase (brewery, fruit juice, pharmaceutical, bakery, and textile), xylanase (bakery, animal feed, textile, pulp and paper), and cellulase (animal feed, biofuel, detergents, textile).
As enzymes are the workhorses of so many industries, using microbes to produce from low-cost waste them could be an effective way to embed circular biomanufacturing into a wide range of industries at scale.
Challenges remain to scale circular fermentation
Modified microbes could offer resource-efficient biofactories for making industrial and consumer compounds from materials that would otherwise rot. Different combinations of strains paired with the right waste organic matter could yield a huge number of different materials and chemicals.
Barriers to setting up a secondary waste bioeconomy based on microbial biotechnology are similar to those in other sectors of the circular bioeconomy. There are economic and logistical ones, relating for example to the cost of collecting waste as well as the techniques needed to sort, clean, and process. But they are also technical, relating to the process of microbial metabolism itself.
Most microbial strains are very inefficient at turning waste feedstocks into useful products and the rate at which bacteria naturally break down waste material is often inadequate for scaled industrial purposes. Scientists are working to solve this by tweaking their genetic makeup. The real breakthrough for scaling is to come up with libraries of microbes that can produce target products from very low-quality wastes that otherwise have no uses.
