Optimisation of culture conditions and characterisation of cutinase produced by recombinant Saccharomyces cerevisiae

Production of secretory cutinase by recombinant Saccharomyces cerevisiae protoplasts

Background

During heterologous protein production using recombinant microbes, the protein tends to accumulate in the cell and may not be secreted. Here, we studied the production of secretory cutinase (heterologous protein) by recombinant Saccharomyces cerevisiae protoplasts.

Findings

Recombinant S. cerevisiae cells (i.e., cells into which the cutinase gene was transferred) secreted trace amounts of cutinase into the broth. Approximately 28 % of the cutinase produced in the cells localized to the cell walls and/or between cell wall and cell membrane (CW). In comparison with cell culture, protoplasts in a static culture secreted measurable amounts of cutinase into the broth. Protoplasts were protected from physical and osmotic stresses by entrapping them in a membrane capsule with a low-viscous liquid-core of 1.92 % w/v calcium-alginate. To increase secretory cutinase production, the entrapped protoplasts were cultivated in a shake flask at low osmotic pressure without disruption. During 60 h of cultivation, the extracellular cutinase activity of the free protoplasts at 29.3 atm and protoplasts entrapped in the capsule at 17.2 atm were 0.13 and 0.39 U/mL, respectively.

Conclusions

This is the first report which demonstrates that the efficient production of a secretable enzyme by using protoplasts isolated from recombinant microbes. This system described here is useful to produce products that accumulate in the CW.

Electronic supplementary material

The online version of this article (doi:10.1186/s40064-016-1806-4) contains supplementary material, which is available to authorized users.

Three New Cutinases from the Yeast Arxula adeninivorans That Are Suitable for Biotechnological Applications

The genes ACUT1, ACUT2, and ACUT3, encoding cutinases, were selected from the genomic DNA of Arxula adeninivorans LS3. The alignment of the amino acid sequences of these cutinases with those of other cutinases or cutinase-like enzymes from different fungi showed that they all had a catalytic S-D-H triad with a conserved G-Y-S-Q-G domain. All three genes were overexpressed in A. adeninivorans using the strong constitutive TEF1 promoter. Recombinant 6× His (6h)-tagged cutinase 1 protein (p) from A. adeninivorans LS3 (Acut1-6hp), Acut2-6hp, and Acut3-6hp were produced and purified by immobilized-metal ion affinity chromatography and biochemically characterized using p-nitrophenyl butyrate as the substrate for standard activity tests. All three enzymes from A. adeninivorans were active from pH 4.5 to 6.5 and from 20 to 30°C. They were shown to be unstable under optimal reaction conditions but could be stabilized using organic solvents, such as polyethylene glycol 200 (PEG 200), isopropanol, ethanol, or acetone. PEG 200 (50%, vol/vol) was found to be the best stabilizing agent for all of the cutinases, and acetone greatly increased the half-life and enzyme activity (up to 300% for Acut3-6hp). The substrate spectra for Acut1-6hp, Acut2-6hp, and Acut3-6hp were quite similar, with the highest activity being for short-chain fatty acid esters of p-nitrophenol and glycerol. Additionally, they were found to have polycaprolactone degradation activity and cutinolytic activity against cutin from apple peel. The activity was compared with that of the 6× His-tagged cutinase from Fusarium solani f. sp. pisi (FsCut-6hp), also expressed in A. adeninivorans, as a positive control. A fed-batch cultivation of the best Acut2-6hp-producing strain, A. adeninivorans G1212/YRC102-ACUT2-6H, was performed and showed that very high activities of 1,064 U ml(-1) could be achieved even with a nonoptimized cultivation procedure.

High-level expression and characterization of Fusarium solani cutinase in Pichia pastoris

High-level extracellular production of Fusarium solani cutinase was achieved using a Pichia pastoris expression system. The cutinase-encoding gene was cloned into pPICZalphaA with the Saccharomyces cerevisiae alpha-factor signal sequence and methanol-inducible alcohol oxidase promoter by two different ways. The additional sequences of the c-myc epitope and (His)6-tag of the vector were fused to the C-terminus of cutinase, while the other expression vector was constructed without any additional sequence. P. pastoris expressing the non-tagged cutinase exhibited about two- and threefold higher values of protein amount and cutinase activity in the culture supernatant, respectively. After simple purification by diafiltration process, both cutinases were much the same in the specific activity and the biochemical properties such as the substrate specificity and the effects of temperature and pH. In conclusion, the high-level secretion of F. solani cutinase in P. pastoris was demonstrated for the first time and would be a promising alternative to many expression systems previously used for the large-scale production of F. solani cutinase in Saccharomyces cerevisiae as well as Escherichia coli.

Production and characterization of recombinant cyprosin B in Saccharomyces cerevisiae (W303-1A) strain

The Saccharomyces cerevisiae W303-1A strain transformed with a centromeric plasmid containing CYPRO11, which codifies the aspartic protease cyprosin B, was grown in a 3 l bioreactor under aerobic conditions. Expression of cyprosin B is directly dependent on the concentration of galactose used as the inducer and carbon source in 1% yeast extract, 2% bactopeptone, and 4% galactose in culture medium. For 4% of galactose, 209 mg.l(-1) total protein, and 1036 U.ml(-1) recombinant cyprosin B activity were obtained from 6.1 g dcw.l(-1) biomass. The recombinant cyprosin B, purified by two consecutive anion-exchange chromatographies (diethyl amino-ethyl [DEAE]-Sepharose and Q-Sepharose XK-16 columns), shows a specific activity of 62 x 10(3) U.mg(-1), corresponding to a purification degree of 12.5-fold and a recovery yield of 25.6% relative to that in fermentation broth. The proteolytic activity of recombinant cyprosin B is optimal at 42 degrees C and pH 4.5. The recombinant cyprosin B activity is 95% inhibited by pepstatin A, which confirms its aspartic protease nature. The pure recombinant cyprosin B is composed of two subunits, one with 14 and the other with 32 kDa. It exhibits clotting activity, similar to that of the natural enzyme from Cynara cardunculus flowers. The results reported here show that recombinant cyprosin B, the first clotting protease of plant origin produced in a bioreactor, can now be produced in large scale and may constitute a new and efficient alternative to enzymes of animal or fungal origin that are widely used in cheese making.

Prediction of retention time of cutinases tagged with hydrophobic peptides in hydrophobic interaction chromatography

Hydrophobic interaction chromatography (HIC) is an important technique for protein purification, which exploits the separation of proteins based on hydrophobic interactions between the stationary phase ligands and hydrophobic regions on the protein surface. One way of enhancing the purification efficiency by HIC is the addition of short sequences of peptide tags to the target protein by genetic engineering, which could reduce the need for extra and expensive chromatographic steps. In the present work, a methodology for predicting retention times of cutinases tagged with hydrophobic peptides in HIC is presented. Cutinase from Fusarium solani pisi fused to tryptophan-proline (WP) tags, namely (WP)2 and (WP)4, and produced in Saccharomyces cerevisiae strains, were used as model proteins. From the simulations, the methodology based on tagged hydrophobic definition proposed by Simeonidis et al. (Phitagged), associated to a quadratic model for predicting dimensionless retention times, showed small differences (RMSE<0.022) between observed and estimated retention times. The difference between observed and calculated retention times being lower than 2.0% (RMSE<0.022) for the two tagged cutinases at three different stationary phases, except for the case of cut_(wp)2 in octyl sepharose-2 M ammonium sulphate. Therefore, we consider that the proposed strategy, based on tagged surface hydrophobicity, allows prediction of acceptable retention times of cutinases tagged with hydrophobic peptides in HIC.

Enhanced cutinase production withThermobifida fusca by two-stage pH control strategy

A mutant of Thermobifida fusca ATCC 27730 was used for cutinase production. Acetate was the most suitable carbon source for cell growth and cutinase production compared with others. The pH was one of the most important factors affecting cutinase yield and productivity. Batch cutinase fermentations by mutant Thermobifida fusca WSH04 at various pH values ranging from 7.0 to 7.9 were studied. Based on the effects of different pH values on the specific cell growth rate and specific cutinase formation rate, a two-stage pH control strategy was developed, in which the pH was set at 7.3 for the first 20 h, and switched to 7.6 afterwards. By applying this two-stage pH control strategy for cutinase fermentation, the maximal cutinase activity reached 19.8 U/mL.

The effect of additives and mechanical agitation in surface modification of acrylic fibres by cutinase and esterase

The surface of an acrylic fibre containing about 7% of vinyl acetate was modified using Fusarium solani pisi cutinase and a commercial esterase, Texazym PES. The effect of acrylic solvents and stabilising polyols on cutinase operational stability was studied. The half-life time of cutinase increased by 3.5-fold with the addition of 15% N,N-dimethylacetamide (DMA) and by 3-fold with 1M glycerol. The impact of additives and mechanical agitation in the protein adsorption and in the hydrolysis of vinyl acetate from acrylic fabric was investigated. The hydroxyl groups produced on the surface of the fibre were able to react specifically with Remazol Brilliant Blue R (cotton reactive dye) and to increase the colour of the acrylic-treated fabric. The best staining level was obtained with a high level of mechanical agitation and with the addition of 1% DMA. Under these conditions, the raise in the acrylic fabric colour depth was 30% for cutinase and 25% for Texazym. The crystallinity degree, determined by X-ray diffraction, was not significantly changed between control samples and samples treated with cutinase. The results showed that the outcome of the application of these enzymes depends closely on the reaction media conditions.

Integration of the production and the purification processes of cutinase secreted by a recombinant Saccharomyces cerevisiae SU50 strain

By expanded bed adsorption (EBA) it was possible to simultaneously recover and purify the heterologous cutinase directly from the crude feedstock. However, it was observed that in a highly condensed and consequently economically advantageous purification process as EBA, the cultivation step highly influences the following purification step. Thus, the yeast cultivation and cutinase purification by EBA cannot be considered as independent entities, and the understanding of the interactions between them are crucial for the development of a highly cost effective overall cutinase production process. From the cultivation strategies studied, one batch, one continuous and two fed-batch cultivations, the strategy that resulted in a more economical cutinase overall production process was a fed-batch mode with a feeding in galactose. This last cultivation strategy, exhibited the highest culture cutinase activity and bioreactor productivity, being obtained 3.8-fold higher cutinase activity and 3.0-fold higher productivity that could compensate the 40% higher cultivation medium costs when compared with a fed-batch culture with a feeding on glucose and galactose. Moreover, a 3.8-fold higher effective cutinase dynamic adsorption capacity and 3.8-fold higher effective purification productivity were obtained in relation to the fed-batch culture with the feeding on glucose and galactose. The cultivation strategy with a feeding on galactose, that presented 5.6-fold higher effective purification productivity, could also compensate the 32% effective adsorption capacity obtained with a continuous cultivation broth. Furthermore, a 205-fold higher cutinase activity, 24-fold higher bioreactor productivity and 6% of the cultivation medium costs were obtained in relation to the continuous culture.

Towards a cost effective strategy for cutinase production by a recombinant Saccharomyces cerevisiae: strain physiological aspects

Although the physiology and metabolism of the growth of yeast strains has been extensively studied, many questions remain unanswered where the induced production of a recombinant protein is concerned. This work addresses the production of a Fusarium solani pisi cutinase by a recombinant Saccharomyces cerevisiae strain induced through the use of a galactose promoter. The strain is able to metabolise the inducer, galactose, which is a much more expensive carbon source than glucose. Both the transport of galactose into the cell-required for the induction of cutinase production-and galactose metabolism are highly repressed by glucose. Different fermentation strategies were tested and the culture behaviour was interpreted in view of the strain metabolism and physiology. A fed-batch fermentation with a mixed feed of glucose and galactose was carried out, during which simultaneous consumption of both hexoses was achieved, as long as the glucose concentration in the medium did not exceed 0.20 g/l. The costs, in terms of hexoses, incurred with this fermentation strategy were reduced to 23% of those resulting from a fermentation carried out using a more conventional strategy, namely a fed-batch fermentation with a feed of galactose.