Waste-to-Profits: Technologies for nutritionally advantaged feeds

The aim of this activity is to deliver technologies that convert wastewater and liquid waste residues directly into animal feeds for use in agriculture and/or aquaculture. The developed technologies will convert abattoir and feedlot waste with a current estimated cost of disposal of >$100 million p.a., into nutritional supplements. 
The key activities in this activity are analysis of waste substrate and microbial products, microorganism selection, strain optimisation, process development, scale up and feed efficacy testing. The major high value product is single cell protein, which typically ranges in value from $300 to $600 per tonne of product, but can exceed $2,000 per tonne in aquaculture. 

Funding

• Australian Government Department of Agriculture, Water and the Environment
• Meat and Livestock Australia

Project Outcome

• Purple phototrophic bacteria enable the removal of organics, nitrogen and phosphorus from agri-industrial wastewater while these resources can be recovered as protein and pigment-rich biomass that is applicable as animal feed or fertiliser. For the first time, PPB were successfully granulated which enables cost-effective harvesting in a wastewater treatment application. The carotenoid content of PPB can be manipulated with light intensity adjustment. The lycopene content, a valuable carotenoid with immuno-nutritional properties, can be increased via this method. A high-throughput screening method to grow PPB, and assess the impacts of environmental conditions on pigmentation was developed. A PPB specific carotenoid analysis method via Ultra Performance Liquid Chromatography (UPLC) was developed which was used to implement a non-destructive principal component analysis (PCA) for high throughput bacteriochlorophyll and carotenoid analysis.
• Preliminary data showed that PPB biomass can substitute up to 100% of fishmeal in tiger prawn feed which technically enables the application of PPB as aquaculture feed with a theoretical value close to fishmeal (~$1970 tonne-1). The wastewater source will dictate the applicability of wastewater derived PPB biomass for the feed manufacturer. 
• PPB were also successfully tested as organic fertiliser (in combination with other fertiliser or as sole source) for tomato, silverbeet, spinach, sorghum and watermelon. The results underline the useability of recovered organics, nitrogen and phosphorus from wastewater to generate plant material and protein in a circular economy. However, the PPB technology is still in its infancy and on-site, outdoor pilot units have to translate the findings into real world applications.

Publications

Papers 

• Capson-Tojo, G., Batstone, D.J., Grassino, M., Vlaeminck, S.E., Puyol, D., Verstraete, W., Kleerebezem, R., Oehmen, A., Ghimire, A., Pikaar, I., Lema, J.M. and Hülsen, T. (2020) Purple phototrophic bacteria for resource recovery: Challenges and opportunities. Biotechnology Advances 43, 107567.
• Stegman, S., Batstone, D.J., Rozendal, R., Jensen, P.D. and Hülsen, T. (2021) Purple phototrophic bacteria granules under high and low upflow velocities. Water Research 190, 116760.
• Grassino, M, Batstone, D.J., Yong, K.W.L, Capson-Tojo, G., Hülsen, T. (2022) A method for detection and quantification of neurosporene, lycopene, and bacteriochlorophyll a in purple phototrophic bacteria by UPLC-UV-HRMS. Talanta (submitted).

Conferences

• 1st Virtual International Conference on Carotenoids (2021). International Carotenoid Society, June 22-25.
• 4th IWA Resource Recovery Conference (2021), Virtual event.

Thesis

• BIOTECHNOLOGY HONOURS 2020. Investigation of processes required for Purple phototrophic bacteria commercialisation (by Glen Cornish)