Reprocessing of side-streams towards obtaining valuable bacterial metabolites

Abstract

Every year, all over the world, the industry generates huge amounts of residues. Side-streams are most often used as feed, landfilled, incinerated, or discharged into sewage. These disposal methods are far from perfect. Taking into account the composition of the side-streams, it seems that they should be used as raw materials for further processing, in accordance with the zero-waste policy and sustainable development. The article describes the latest achievements in biotechnology in the context of bacterial reprocessing of residues with the simultaneous acquisition of their metabolites. The article focuses on four metabolites — bacterial cellulose, propionic acid, vitamin B12 and PHAs. Taking into account global trends (e.g. food, packaging, medicine), it seems that in the near future there will be a sharp increase in demand for this type of compounds. In order for their production to be profitable and commercialised, cheap methods of its obtaining must be developed. The article, in addition to obtaining these bacterial metabolites from side-streams, also discusses e.g. factors affecting their production, metabolic pathways and potential and current applications. The presented chapters provide a complete overview of the current knowledge on above metabolites, which can be helpful for the academic and scientific communities and the several industries. Key points • The industry generates millions of tons of organic side-streams each year. • Generated residues burden the natural environment. • A good and cost-effective method of side-streams management seems to be biotechnology – reprocessing with the use of bacteria. • Biotechnological disposal of side-streams gives the opportunity to obtain valuable compounds in cheaper ways: BC, PA, vitmain B12, PHAs.

The Nitrogen Content in the Fruiting Body and Mycelium of Pleurotus Ostreatus and Its Utilization as a Medium Component in Thraustochytrid Fermentation

“…For the cultivation of microorganisms in need of more accessible nutrients, side streams must be pretreated [ 12 ]. The most common methods used to release nutrients like carbon or nitrogen sources are heat or pressure treatments as well as hydrolyses (acidic, alkaline or enzymatic) and hot water extraction [ 13 ].…”

Gorse (Ulex europeaus) wastes with 5,6-dimethyl benzimidazole supplementation can support growth of vitamin B12 producing commensal gut microbes

“…Interestingly, this has lead to investigations on waste stream valorisation with cobalt and DMB supplementation for the growth of B 12 producing bacteria. For example, P. freudenreichii has been shown to grow on apple pomace and potato wastes for large scale production of propionic acid, with vitamin B 12 obtained as a secondary product in significant quantities [ 13 , 14 ]. Such endeavours help generate high-value products and circularise waste streams otherwise fated for landfill or waste-water treatment plants.…”

Quality Characteristics of Raspberry By-Products for Sustainable Production

“…The contemporary challenges faced by industries, scientists, and humanity as a whole are reducing food waste, optimizing production processes (minimizing sidestream production), and valorizing residues to obtain valuable and sustainable products. It is important to ensure that all by-products constitute a resource/raw material that can be further used [6].…”