Chaotropicity: a key factor in product tolerance of biofuel-producing microorganisms

Fermentation products can chaotropically disorder macromolecular systems and induce oxidative stress, thus inhibiting biofuel production. Recently, the chaotropic activities of ethanol, butanol and vanillin have been quantified (5.93, 37.4, 174kJkg(-1)m(-1) respectively). Use of low temperatures and/or stabilizing (kosmotropic) substances, and other approaches, can reduce, neutralize or circumvent product-chaotropicity. However, there may be limits to the alcohol concentrations that cells can tolerate; e.g. for ethanol tolerance in the most robust Saccharomyces cerevisiae strains, these are close to both the solubility limit (<25%, w/v ethanol) and the water-activity limit of the most xerotolerant strains (0.880). Nevertheless, knowledge-based strategies to mitigate or neutralize chaotropicity could lead to major improvements in rates of product formation and yields, and also therefore in the economics of biofuel production.

Ultrashort self-assembling peptidomimetic nanomaterials target resistant pathogenic infections

The impending and increasing threat of antimicrobial resistance has led to a greater focus into developing alternative therapies as substitutes for traditional antibiotics for the treatment of multi-drug resistant infections.1 Our group has developed a library of short, cost-effective, diphenylalanine-based peptides (X1-FF-X2) which selective eradicate (viability reduced >90% in 24 hours) the most resistant biofilm forms of a range of Gram-positive and negative pathogens including: methicillin resistant and sensitive Staphyloccoccus aureus and Staphyloccoccus epidermidis; Pseudomonas aeruginosa, Proteus mirabilis and Escherichia coli. They demonstrate a reduced cell cytotoxic profile (NCTC929 murine fibroblast) and limited haemolysis.2 Our molecules have the ability respond to subtle changes in pH, associated with bacterial infection, self-assembling to form β-sheet secondary structures and supramolecular hydrogels at low concentrations (~0.5%w/v). Conjugation of variety of aromatic-based drugs at the X1 position, including non-steroidal anti-inflammatories (NSAIDs), confer further pharmacological properties to the peptide motif enhancing their therapeutic potential. In vivo studies using waxworms (Galleria mellonella) provide promising preliminary results demonstrating the low toxicity and high antimicrobial activity of these low molecular weight gelators in animal models. This work shows biofunctional peptide-based nanomaterials hold great promise for future translation to patients as antimicrobial drug delivery and biomaterial platforms.3 [1] G. Laverty, S.P. Gorman and B.F. Gilmore. Int.J.Mol.Sci. 2011, 12, 6566-6596. [2] G. Laverty, A.P. McCloskey, B.F. Gilmore, D.S. Jones, J Zhou, B Xu. Biomacromolecules. 2014, 15, 9, 3429-3439. [3] A.P. McCloskey, B.F. Gilmore and G.Laverty. Pathogens. 2014, 3, 791-821.

Glycine betaine-mediated protection of peas (Pisum sativum L.) during blanching and frozen storage

We used glycine betaine (5–20% w/v) for blanching green peas (100°C, 60 s), and their subsequent freezing and storage (–20°C, 90 days). Blanching after the addition of glycine betaine at ≥10% (w/v) followed by a 90 day storage period which resulted in the most desirable outcome: higher vitamin C levels, a superior green color, enhanced organoleptic quality and texture, and improved retention of peroxidase and lipoxygenase activity relative to control peas (no glycine betaine added). Microscopic characterizations of control and treated peas revealed that glycine betaine acts as a cryoprotectant which maintains cellular integrity. Glycine betaine (10% w/v) could be used commercially for production of frozen peas with better quality attributes.