Chemoenzymatic indican for light-driven denim dyeing

Blue denim, a billion-dollar industry, is currently dyed with indigo in an unsustainable process requiring harsh reducing and alkaline chemicals. Forming indigo directly in the yarn through indican (indoxyl-β-glucoside) is a promising alternative route with mild conditions. Indican eliminates the requirement for reducing agent while still ending as indigo, the only known molecule yielding the unique hue of blue denim. However, a bulk source of indican is missing. Here, we employ enzyme and process engineering guided by techno-economic analyses to develop an economically viable drop-in indican synthesis technology. Rational engineering of PtUGT1, a glycosyltransferase from the indigo plant, alleviated the severe substrate inactivation observed with the wildtype enzyme at the titers needed for bulk production. We further describe a mild, light-driven dyeing process. Finally, we conduct techno-economic, social sustainability, and comparative life-cycle assessments. These indicate that the presented technologies have the potential to significantly reduce environmental impacts from blue denim dyeing with only a modest cost increase.

Correction to: Application of a multiphase microreactor chemostat for the determination of reaction kinetics of Staphylococcus carnosus

Unfortunately, in the "How to Cite as" section, the given and the family name of the author was incorrectly published, the correct name is Lladó Maldonado. S.

Application of a multiphase microreactor chemostat for the determination of reaction kinetics of Staphylococcus carnosus

Bioreactors at the microliter scale offer a promising approach to accelerate bioprocess development. Advantages of such microbioreactors include a reduction in the use of expensive reagents. In this study, a chemostat operation mode of a cuvette-based microbubble column bioreactor made of polystyrene (working volume of 550 µL) was demonstrated. Aeration occurs through a nozzle (Ø ≤ 100 µm) and supports submerged whole-cell cultivation of Staphylococcus carnosus. Stationary concentrations of biomass and glucose were determined in the dilution rate regime ranging from 0.12 to 0.80 1/h with a glucose feed concentration of 1 g/L. For the first time, reaction kinetics of S. carnosus were estimated from data obtained from continuous cultivation. The maximal specific growth rate (µ_max = 0.824 1/h), Monod constant (K_S = 34 × 10^{- 3}g_S/L), substrate-related biomass yield coefficient (Y_X/S = 0.315 g_CDW/g_S), and maintenance coefficient (m_S = 0.0035 g_S/(g_CDW·h)) were determined. These parameters are now available for further studies in the field of synthetic biology.

Detection of hormone mimics in water using a miniturised SPR sensor

The ubiquitous presence of chemicals, both natural and synthetic, in the environment with the potential to mimic hormones that may in turn interfere with the endocrine system in both wildlife and humans has in the last decade become a major international concern. Hormone mimics or endocrine disrupting compounds (EDCs) are especially prevalent in surface and waste-waters and therefore, there is a need for an at-source or at-line analytical device for the monitoring of EDC levels. We have incorporated a miniature integrated surface plasmon resonance (SPR) liquid sensor from Texas Instruments into a field analyser and developed a competition/inhibition assay for a model estrogenic compound in aqueous samples. The analyser has the potential for in situ and semi-continuous analysis of EDCs. A novel regeneration scheme employing the use of a domestic laundry detergent has been used to remove immobilised assay components between each assay cycle. The resultant re-usable sensor has been demonstrated using estrone-3-glucuronide (E3G) as a model EDC and an anti-E3G antibody producing a current detection range of 10 to 150 ng mL(-1).