A new physical and biological strategy to reduce the content of zearalenone in infected wheat kernels: the effect of cold needle perforation, microorganisms, and purified enzyme.

With the aim of reintroducing wheat grains naturally contaminated with mycotoxins into the food value chain, a decontamination strategy was developed in this study. For this purpose, in a first step, the whole wheat kernels were pre-treated using cold needle perforation. The pore size was evaluated by scanning electron microscopy and the accessibility of enzymes and microorganisms determined using fluorescent markers in the size range of enzymes (5 nm) and microorganisms (10 µm), and fluorescent microscopy. The perforated wheat grains, as well as non-perforated grains as controls, were then incubated with selected microorganisms (Bacillus megaterium Myk145 and B. licheniformis MA572) or with the enzyme ZHD518. The two bacilli strains were not able to significantly reduce the amount of zearalenone (ZEA), neither in the perforated nor in the non-perforated wheat kernels in comparison with the controls. In contrast, the enzyme ZHD518 significantly reduced the initial concentration of ZEA in the perforated and non-perforated wheat kernels in comparison with controls. Moreover, in vitro incubation of ZHD518 with ZEA showed the presence of two non-estrogenic degradation products of ZEA: hydrolysed zearalenone (HZEA) and decarboxylated hydrolysed ZEA (DHZEA). In addition, the physical pre-treatment led to a reduction in detectable mycotoxin contents in a subset of samples. Overall, this study emphasizes the promising potential of combining physical pre-treatment approaches with biological decontamination solutions in order to address the associated problem of mycotoxin contamination and food waste reduction.

Enzymatic PET Degradation.

Plastic, in the form of packaging material, disposables, clothing and other articles with a short lifespan, has become an indispensable part of our everyday life. The increased production and use of plastic, however, accelerates the accumulation of plastic waste and poses an increasing burden on the environment with negative effects on biodiversity and human health. PET, a common thermoplastic, is recycled in many countries via thermal, mechanical and chemical means. Recently, several enzymes have been identified capable of degrading this recalcitrant plastic, opening possibilities for the biological recycling of the omnipresent material. In this review, we analyze the current knowledge of enzymatic PET degradation and discuss advances in improving the involved enzymes via protein engineering. Looking forward, the use of plastic degrading enzymes may facilitate sustainable plastic waste management and become an important tool for the realization of a circular plastic economy.

10th Wädenswil Day of Life Sciences Hosts 2nd CCBIO Symposium 'Industrial Biocatalysis'.

The chemical industry is under increasing pressure to manufacture chemicals that match not only economic targets but also fulfill societal and environmental objectives. These requirements necessitate the adoption of new approaches and consequently the pace of application of biocatalysis in the chemical industry is increasing. The 10th Wädenswil Day of Life Sciences on June 7th, 2018 focused for the second time on 'Industrial Biocatalysis'. Upon invitation of the Competence Center of Biocatalysis (CCBIO) international experts in the field gave an update about their current research interests and attracted more than a hundred guests from industry and academia.

Effects of glycerol supply and specific growth rate on methanol-free production of CALB by P. pastoris: functional characterisation of a novel promoter.

As Pichia pastoris (syn. Komagataella sp.) yeast can secrete pure recombinant proteins at high rates, it is a desirable production system. The function of a novel synthetic variant of the AOX1 promoter was characterised comprehensively using a strain secreting Candida antarctica lipase B (CALB) as a model. A new time-saving approach was introduced to determine, in only one experiment, the hitherto unknown relationship between specific product formation rate (q p) and specific growth rate (µ). Tight control of recombinant protein formation was possible in the absence of methanol, while using glycerol as a sole carbon/energy source. CALB was not synthesised during batch cultivation in excess glycerol (>10 g l-1) and at a growth rate close to µ max (0.15 h-1). Between 0.017 and 0.115 h-1 in glycerol-limited fedbatch cultures, basal levels of q p > 0.4 mg g-1 h-1 CALB were reached, independent of the µ at which the culture grew. At µ > 0.04 h-1, an elevated q p occurred temporarily during the first 20 h after changing to fedbatch mode and decreased thereafter to basal. In order to accelerate the determination of the q p(µ) relationship (kinetics of product formation), the entire µ range was covered in a single fedbatch experiment. By linearly increasing and decreasing glycerol addition rates, µ values were repeatedly shifted from 0.004 to 0.074 h-1 and vice versa. Changes in q p were related to changes in µ. A rough estimation of µ range suitable for production was possible in a single fedbatch, thus significantly reducing the experimental input over previous approaches comprising several experiments.

Innovation in Biocatalysis - A Swiss Network Project Coordinated by the Competence Center for Biocatalysis (CCBIO).

Biocatalysis - the application of enzymes or microbes in chemistry - has developed into one of the key technologies of the 21st century. Enzymes in isolated form, as a cell extract or whole cell biocatalysts can be used to replace or supplement purely chemical process routes with the goal to make chemical synthesis more efficient, environmentally friendly, sustainable and potentially more cost-effective.

Sulforaphane Preconditioning Sensitizes Human Colon Cancer Cells towards the Bioreductive Anticancer Prodrug PR-104A.

The chemoprotective properties of sulforaphane (SF), derived from cruciferous vegetables, are widely acknowledged to arise from its potent induction of xenobiotic-metabolizing and antioxidant enzymes. However, much less is known about the impact of SF on the efficacy of cancer therapy through the modulation of drug-metabolizing enzymes. To identify proteins modulated by a low concentration of SF, we treated HT29 colon cancer cells with 2.5 µM SF. Protein abundance changes were detected by stable isotope labeling of amino acids in cell culture. Among 18 proteins found to be significantly up-regulated, aldo-keto reductase 1C3 (AKR1C3), bioactivating the DNA cross-linking prodrug PR-104A, was further characterized. Preconditioning HT29 cells with SF reduced the EC50 of PR-104A 3.6-fold. The increase in PR-104A cytotoxicity was linked to AKR1C3 abundance and activity, both induced by SF in a dose-dependent manner. This effect was reproducible in a second colon cancer cell line, SW620, but not in other colon cancer cell lines where AKR1C3 abundance and activity were absent or barely detectable and could not be induced by SF. Interestingly, SF had no significant influence on PR-104A cytotoxicity in non-cancerous, immortalized human colonic epithelial cell lines expressing either low or high levels of AKR1C3. In conclusion, the enhanced response of PR-104A after preconditioning with SF was apparent only in cancer cells provided that AKR1C3 is expressed, while its expression in non-cancerous cells did not elicit such a response. Therefore, a subset of cancers may be susceptible to combined food-derived component and prodrug treatments with no harm to normal tissues.

Transcriptomic responses of cancerous and noncancerous human colon cells to sulforaphane and selenium.

Diets enriched with bioactive food components trigger molecular changes in cells that may contribute to either health-promoting or adverse effects. Recent technological advances in high-throughput data generation allow for observing systems-wide molecular responses to cellular perturbations with nontoxic and dietary-relevant doses while considering the intrinsic differences between cancerous and noncancerous cells. In this chemical profile, we compared molecular responses of the colon cancer cell line HT29 and a noncancerous colon epithelial cell line (HCEC) to two widely encountered food components, sulforaphane and selenium. We conducted this comparison by generating new transcriptome data by microarray gene-expression profiling, analyzing them statistically on the single gene, network, and functional pathway levels, and integrating them with protein expression data. Sulforaphane and selenium, at doses that did not inhibit the growth of the tested cells, induced or repressed the transcription of a limited number of genes in a manner distinctly dependent on the chemical and the cell type. The genes that most strongly responded in cancer cells were observed after treatment with sulforaphane and were members of the aldo-keto reductase (AKR) superfamily. These genes were in high agreement in terms of fold change with their corresponding proteins (correlation coefficient r(2) = 0.98, p = 0.01). Conversely, selenium had little influence on the cancer cells. In contrast, in noncancerous cells, selenium induced numerous genes involved in apoptotic, angiogenic, or tumor proliferation pathways, whereas the influence of sulforaphane was very limited. These findings contribute to defining the significance of cell type in interpreting human cellular transcriptome-level responses to exposures to natural components of the diet.

Polycistronic gene expression in yeast versus cryptic promoter elements.

Saccharomyces cerevisiae is a much preferred host for biotechnological applications. However, the expression of entire heterologous pathways, required for some potential products, is technically challenging in yeast. A possible tool would be polycistronic gene expression. Recent studies demonstrated that short 5' untranslated regions (5'UTRs) found upstream of certain genes support cap-independent translation in vitro. In this study 5'UTRs were used as linkers between genes in polycistronic constructs. Expression levels of genes located in the first, second and third position after a promoter were studied by replacing the respective gene by a promoterless green fluorescence protein (GFP) gene. S. cerevisiae transformed with these constructs was grown on different carbon sources and GFP expression was assayed. Our results demonstrate that (i) ribosomal read-through does not suffice for polycistronic gene expression in vivo, (ii) 5'TFIID and 5'HAP4 but not 5'L-A significantly improve the expression of a reporter gene located second in a bicistron, (iii) 5'TFIID, 5'HAP4 and 5'YAP1 but not 5'L-A can drive expression of a promoterless reporter gene, and (iv) expression driven from 5'TFIID, 5'HAP4 and 5'YAP1 is induced in the presence of raffinose or galactose but not in the presence of glucose. This implies that these elements unlike typical internal ribosome entry site-like structures contain small, potentially useful promoters which support carbon source-regulated expression.