New Lignosulfonates as next generation antimicrobials

This research project aligns with BBSRC and IBioIC priorities through its relevance to the use of Sustainable Feedstocks; the role of biocatalysis and biotransformation and ultimately the impact it could have on downstream processing in the context of Industrial Biotechnology. As this is a CTP-funded PhD (IBioIC-CTP) a key component is the industrial relevance:
The Industrial Challenges: Two main industrial challenges have been selected as goals of this PhD:
Challenge 1. Novel Lignosulfonates as antimicrobials: Preservatives are used to make a product safer by preventing contamination with micro-organisms (bacteria, yeast and moulds) - i.e. a preservative exhibits antimicrobial activity. Several factors, including the withdrawal from commercial use of established preservatives, have led to a major industrial need for novel non-petrochemical derived preservatives. Research has shown that the biomass-derived polymer lignin (including industrial lignosulfonates) can be used as a component of novel antimicrobials (providing a key antioxidative activity due to phenolic groups in the structure). Here we will assess the antimicrobial activity of a novel form of lignosulfonates that we have discovered both on its own, in a chemically-modified form and in combination with other materials. This work will be driven by the Scottish SME BluTest with the PhD student spending 9 months supervised by Dr Emma Millhouse at BluTest developing core skills in microbiology and antimicrobial R&D in a QA, ISO 17025 accredited lab.
Challenge 2. Industrial applications of our new lignosulfonates in cleaning products: Most common cleaning products contain polymers that function as e.g. colloidal soil stabilisers or as substrate modifiers to enable easier next wash cleaning. Their use reduces the level of surfactants that are required hence improving the environmental impact of the product. Unfortunately, these polymers often come from petrochemical sources and naturally derived equivalents are currently unavailable at the desired volume and cost. The only mainstream exception is Sodium Carboxy Methyl Cellulose (SCMC). SCMC is used but i) it's benefits in terms of cleaning are limited - it doesn't fulfil many of the desired cleaning functions; ii) incorporation into certain formats is difficult; iii) it is based on the high value cellulose component and not a waste stream iv) natural polysaccharide chemistry can be extremely complex and resource intensive. There is an industrial need for naturally derived cleaning polymers that meet all the functionality requirements. We believe that the novel biomass-derived lignosulfonate oligomers recently prepared in the Westwood group could impact on this challenge.
A detailed technical plan involving 12 (9 + 3 months) industrial placement and 16 project milestones has been developed across 4 project goals.
Project Goal 1: Scaled-up preparation of novel lignin-derived water soluble oligomeric backbones
Project Goal 2: Fractionation of our novel polymeric backbones
Project Goals 3 and 4: Design and modify of our fractionated oligomeric backbones to incorporate: (i) additional antimicrobial units and (ii) alternating blocks of hydrophobic and hydrophilic regions (for cleaning applications). Test desired properties.
Summary: In contrast to the well-known industrial lignosulfonates, the oligomers used in this project, which were discovered in the Westwood group, are well-defined lower molecular weight materials. Our lignosulfonates, which are still made from lignin, are sparingly sulfonated (and hence water soluble) but, unlike industrial lignosulfonates, still contain many of the linkages present in native lignin. This means that they can be modified to generate designer materials of industrial relevance (e.g. antimicrobial additives). This project builds on advances from the Westwood group and culminates in the assessment of the industrial relevance of the novel materials we will make.