Biocatalytic valorisation of flower waste: Towards sustainable feedstock for fine chemical industry

Did you know countries like India produce more than 300 kilotons of flower waste every day? Imagine re-using the flower waste to make high value starting materials for the chemical industry!

With an increasing awareness about resource use and government regulation, chemical industries are fast realising the need for sustainable manufacturing. Identifying sustainable alternatives for petrochemical feedstock (like biomass) and using resource efficient technologies (to replace the conventional batch reactor) are two strategies which are fast gaining research and industry attention to enable sustainable production of chemicals.

In this two-fold objective project we will: (i) demonstrate for the first time the potential of Streptomyces sp. as a biocatalyst for valorisation of flower waste into high value chemicals and (ii) investigate process scale-up in continuous reactors.

Flowers are an abundant source of aromatic and biologically active compounds, which are important raw materials for the food, pharmaceutical and the cosmetic industry. Currently, these compounds are either obtained from fresh flowers or produced using synthetic routes, both of which are not sustainable solutions in the long run. This project will focus on the conversion of terpene alcohols (commonly present in flower biomass) into terpene esters and methacrylate, which are important starting materials for food, fragrance and polymer industries.

The limitations of current state-of-the-art to produce these compounds are: (i) long reaction times due to mass transfer limitations, (ii) loss in product yield due to product inhibition and (iii) limited reusability of expensive enzymes. Microbes like Streptomyces sp. are an attractive solution to challenges associated with metal and metal organic catalysts (toxic, expensive and susceptible to catalyst poisoning) and provide a benign pathway to carry out chemical transformations. Streptomyces sp. are ubiquitous in the natural environment and excrete a large number of extracellular enzymes for the solubilisation of plant-derived polymers.

The first part of this project will first focus on investigating the reaction mechanism for biocatalytic conversion of terpene alcohols derived from flower waste. This involves identifying the right reaction conditions to maximise the product yield on the bench scale. This reaction will be carried out using both free and immobilised Streptomyces sp. The second part of the project involves applying the reaction protocol developed in the first stage to demonstrate scale-up in micro-channel (MC) and spinning disc reactors (SDR). These reactor configurations are fast gaining industry attention for their ability to achieve fast reactions due to increased mass transfer, small chemical inventory, scalability and inherent safety. This project for the first time will test the potential of the MC and SDR for whole cell catalysed reaction systems.

This is largely an experimental project with ample training opportunities in analytical and characterisation techniques, bioreactor development and optimisation. The project also allows for additional skills development through participation in research group meetings, presentation in seminars and conferences, industry and public engagement.