Carbon and nitrogen sources modulate lipase production in the yeast Yarrowia lipolytica

Adding value to the oil cake as a waste from oil processing industry: production of lipase and protease by Candida utilis in solid state fermentation

Olive oil cake is a by-product from the olive oil processing industry and can be used for the lipase and protease production by Candida utilis in solid state fermentation. Different carbon and nitrogen sources were evaluated, and the results showed that the supplementation of the substrate with maltose and starch as carbon sources and yeast extract as a nitrogen source significantly increased the lipase production. The best results were obtained with maltose, whereas rather low lipase and protease activities were found with glucose and oleic acid. Response surface methodology and a five-level-three-factor central composite rotatable design were used to evaluate the effects of the initial moisture content, inoculum size and fermentation time on both lipase and protease activity levels. A lipase activity value of ≈25 U g(-1) and a protease activity value of 110 U g(-1) were obtained under the optimized fermentation conditions. An alkaline treatment of the substrate appeared to be efficient, leading to increases of 39% and 133% in the lipase and protease production, respectively. The results showed that the olive cake could be a good source for enzyme production by solid state fermentation.

Differential induction, purification and characterization of cold active lipase from Yarrowia lipolytica NCIM 3639

The production, purification and characterization of cold active lipases by Yarrowia lipolytica NCIM 3639 is described. The study presents a new finding of production of cell bound and extracellular lipase activities depending upon the substrate used for growth. The strain produced cell bound and extracellular lipase activity when grown on olive oil and Tween 80, respectively. The organism grew profusely at 20 °C and at initial pH of 5.5, producing maximum extracellular lipase. The purified lipase has a molecular mass of 400 kDa having 20 subunits forming a multimeric native protein. Further the enzyme displayed an optimum pH of 5.0 and optimum temperature of 25 °C. Peptide mass finger printing reveled that some peptides showed homologues sequence (42%) to Yarrowia lipolytica LIP8p. The studies on hydrolysis of racemic lavandulyl acetate revealed that extracellular and cell bound lipases show preference over the opposite antipodes of irregular monoterpene, lavandulyl acetate.

Design of an efficient medium for heterologous protein production in Yarrowia lipolytica: case of human interferon alpha 2b

Background

The non conventional yeast Yarrowia lipolytica has aroused a strong industrial interest for heterologous protein production. However most of the studies describing recombinant protein production by this yeast rely on the use of complex media, such media are not convenient for large scale production particularly for products intended for pharmaceutical applications. In addition medium composition can also affect the production yield. Hence it is necessary to design an efficient medium for therapeutic protein expression by this host.

Results

Five different media, including four minimal media and a complex medium, were assessed in shake flasks for the production of human interferon alpha 2b (hIFN α2b) by Y. lipolytica under the control of POX2 promoter inducible with oleic acid. The chemically defined medium SM4 formulated by Invitrogen for Pichia pastoris growth was the most suitable. Using statistical experimental design this medium was further optimized. The selected minimal medium consisting in SM4 supplemented with 10 mg/l FeCl₃, 1 g/l glutamate, 5 ml/l PTM1 (Pichia Trace Metals) solution and a vitamin solution composed of myo-inositol, thiamin and biotin was called GNY medium. Compared to shake flask, bioreactor culture in GNY medium resulted in 416-fold increase of hIFN α2b production and 2-fold increase of the biological activity.

Furthermore, SM4 enrichment with 5 ml/l PTM1 solution contributed to protect hIFN α2b against the degradation by the 28 kDa protease identified by zymography gel in culture supernatant. The screening of the inhibitory effect of the trace elements present in PTM1 solution on the activity of this protease was achieved using a Box-Behnken design. Statistical data analysis showed that FeCl₃ and MnSO₄ had the most inhibitory effect.

Conclusion

We have designed an efficient medium for large scale production of heterologous proteins by Y. lipolytica. The optimized medium GNY is suitable for the production of hIFN α2b with the advantage that no complex nitrogen sources with non-defined composition were required.

The effect of volatile fatty acids as a sole carbon source on lipid accumulation by Cryptococcus albidus for biodiesel production

The use of volatile fatty acids (VFAs) for microbial lipid accumulation was investigated in flask cultures of Cryptococcus albidus. The optimum culture temperature and pH were 25°C and pH 6.0, respectively, and the highest lipid content (27.8%) was obtained with ammonia chloride as a nitrogen source. The lipid yield coefficient on VFAs was 0.167 g/g of C. albidus with a VFAs (acetic, propionic, butyric acids) ratio of 8:1:1, which was in good agreement with a theoretically predicted lipid yield coefficient of the VFAs as a carbon source. The major fatty acids of the lipids accumulated by C. albidus were similar to those of soybean oil and jatropha oil. A preliminary cost analysis shows that VFAs-based biodiesel production is competitive with current palm and soybean based biodiesels. Further process development for lower aeration cost and higher lipid yield will make this process more economical.

Quantitative study of lipase secretion, extracellular lipolysis, and lipid storage in the yeast Yarrowia lipolytica grown in the presence of olive oil: analogies with lipolysis in humans

Lipase secretion, extracellular lipolysis, and fatty acid uptake were quantified in the yeast Yarrowia lipolytica grown in the presence of olive oil and/or glucose. Specific lipase assays, Western blot analysis, and ELISA indicated that most of the lipase activity measured in Y. lipolytica cultures resulted from the YLLIP2 lipase. Lipase production was triggered by olive oil and, during the first hours of culture, most of the lipase activity and YLLIP2 immunodetection remained associated with the yeast cells. YLLIP2 was then released in the culture medium before it was totally degraded by proteases. Olive oil triglycerides were largely degraded when the lipase was still attached to the cell wall. The fate of lipolysis products in the culture medium and inside the yeast cell, as well as lipid storage, was investigated simultaneously by quantitative TLC-FID and GC analysis. The intracellular levels of free fatty acids (FFA) and triglycerides increased transiently and were dependent on the carbon sources. A maximum fat storage of 37.8% w/w of yeast dry mass was observed with olive oil alone. A transient accumulation of saturated FFA was observed whereas intracellular triglycerides became enriched in unsaturated fatty acids. So far, yeasts have been mainly used for studying the intracellular synthesis, storage, and mobilization of neutral lipids. The present study shows that yeasts are also interesting models for studying extracellular lipolysis and fat uptake by the cell. The quantitative data obtained here allow for the first time to establish interesting analogies with gastrointestinal and vascular lipolysis in humans.

Characterization of a multimeric, eukaryotic prolyl aminopeptidase: an inducible and highly specific intracellular peptidase from the non-pathogenic fungus Talaromyces emersonii

Fungi are capable of degrading proteins in their environment by secreting peptidases. However, the link between extracellular digestion and intracellular proteolysis has scarcely been investigated. Mycelial lysates of the filamentous fungus Talaromyces emersonii were screened for intracellular peptidase production. Five distinct proteolytic activities with specificity for the p-nitroanilide (pNA) peptides Suc-AAPF-pNA, Suc-AAA-pNA, K-pNA, F-pNA and P-pNA were identified. The native enzyme responsible for the removal of N-terminal proline residues was purified to homogeneity by ammonium sulfate fractionation followed by five successive chromatographic steps. The enzyme, termed Talaromyces emersonii prolyl aminopeptidase (TePAP), displayed a 50-fold specificity for cleaving N-terminal Pro-X (k(cat)/K(m)=2.1 x 10(6) M(-1) s(-1)) compared with Ala-X or Val-X bonds. This intracellular aminopeptidase was optimally active at pH 7.4 and 50 degrees C. Peptide sequencing facilitated the design of degenerate oligonucleotides from homologous sequences encoding putative fungal proline aminopeptidases, enabling subsequent cloning of the gene. TePAP was shown to be relatively uninhibited by classical serine peptidase inhibitors and to be sensitive to selected cysteine- and histidine-modifying reagents, yet gene sequence analysis identified the protein as a serine peptidase with an alpha/beta hydrolase fold. Northern analysis indicated that Tepap mRNA levels were regulated by the composition of the growth medium. Highest Tepap transcript levels were observed when the fungus was grown in medium containing glucose and the protein hydrolysate casitone. Interestingly, both the induction profile and substrate preference of this enzyme suggest potential co-operativity between extracellular and intracellular proteolysis in this organism. Gel filtration chromatography suggested that the enzyme exists as a 270 kDa homo-hexamer, whereas most bacterial prolyl aminopeptidases (PAPs) are monomers. Phylogenetic analysis of known PAPs revealed two diverse subfamilies that are distinguishable on the basis of primary and secondary structure and appear to correlate with the subunit composition of the native enzymes. Sequence comparisons revealed that PAPs with key conserved topological features are widespread in bacterial and fungal kingdoms, and this study identified many putative PAP candidates within sequenced genomes. This work represents, to our knowledge, the first detailed biochemical and molecular analysis of an inducible PAP from a eukaryote and the first intracellular peptidase isolated from the thermophilic fungus T. emersonii.

SOA genes encode proteins controlling lipase expression in response to triacylglycerol utilization in the yeast Yarrowia lipolytica

The oleaginous yeast Yarrowia lipolytica efficiently metabolizes hydrophobic substrates such as alkanes, fatty acids or triacylglycerol. This yeast has been identified in oil-polluted water and in lipid-rich food. The enzymes involved in lipid breakdown, for use as a carbon source, are known, but the molecular mechanisms controlling the expression of the genes encoding these enzymes are still poorly understood. The study of mRNAs obtained from cells grown on oleic acid identified a new group of genes called SOA genes (specific for oleic acid). SOA1 and SOA2 are two small genes coding for proteins with no known homologs. Single- and double-disrupted strains were constructed. Wild-type and mutant strains were grown on dextrose, oleic acid and triacylglycerols. The double mutant presents a clear phenotype consisting of a growth defect on tributyrin and triolein, but not on dextrose or oleic acid media. Lipase activity was 50-fold lower in this mutant than in the wild-type strain. The impact of SOA deletion on the expression of the main extracellular lipase gene (LIP2) was monitored using a LIP2-beta-galactosidase promoter fusion protein. These data suggest that Soa proteins are components of a molecular mechanism controlling lipase gene expression in response to extracellular triacylglycerol.

Effect of plant oils upon lipase and citric acid production in Yarrowia lipolytica yeast

The nonconventional yeast Yarrowia lipolytica degrades very efficiently hydrophobic substrates to produce organic acids, single-cell oil, lipases, and so forth. The aim of this study was to investigate the biochemical behavior and simultaneous production of valuable metabolites such as lipase, citric acid (CA), and single-cell protein (SCP) by Yarrowia lipolytica DSM 3286 grown on various plant oils as sole carbon source. Among tested plant oils, olive oil proved to be the best medium for lipase and CA production. The Y. lipolytica DSM 3286 produced 34.6 ± 0.1 U/mL of lipase and also CA and SCP as by-product on olive oil medium supplemented with yeast extract. Urea, as organic nitrogen, was the best nitrogen source for CA production. The results of this study suggest that the two biotechnologically valuable products, lipase and CA, could be produced simultaneously by this strain using renewable low-cost substrates such as plant oils in one procedure.

Evaluation of nitrogenous media components by Plackett–Burman statistical design for β-d-fructofuranosidase production by Saccharomyces sp. strain GVT263

β-d-Fructofuranosidase (FFase), an important enzyme of the confectionery and fructose syrup industry, is produced by several microorganisms. However, yeasts are the most used source because of their high sucrose fermentation capacity. In this work, production of FFase was carried out in submerged fermentation using a high enzyme-producing yeast strain. Plackett–Burman statistical experimental design was applied to evaluate the fermentation medium components. The effects of 10 nitrogen sources were studied in a 16-run experimental design. Beef extract, yeast extract, N-Z-amine, tryptone, meat extract, and ammonium acetate were found to have significant effects on enzyme production. Among these, yeast extract, N-Z-amine, and ammonium acetate were the most significant. A maximum FFase activity of 299.4 U/mL was obtained after a 24 h fermentation period.

An enhanced process for the production of a highly purified extracellular lipase in the non-conventional yeast Yarrowia lipolytica

Yarrowia lipolytica LgX64.81 is a non-genetically modified mutant that was previously identified as a promising microorganism for extracellular lipase production. In this work, the development of a fed-batch process for the production of this enzyme in this strain was described. A lipolytic activity of 2,145 U/mL was obtained after 32 h of batch culture in a defined medium supplemented with 10 g/L of tryptone, an enhancer of lipase expression. To maximize the volumetric productivity, two different fed-batch strategies had been investigated. In comparison to batch process, the intermittent fed-batch strategy had not improved the volumetric lipase productivity. In contrast, the stepwise feeding strategy combined with uncoupled cell growth and lipase production phases resulted in a 2-fold increase in the volumetric lipase productivity, namely, the lipase activity reached 10,000 U/mL after 80 h of culture. Furthermore, this lipase was purified to homogeneity by anion exchange chromatography on MonoQ resin followed by gel filtration on Sephacryl S-100. This process resulted in an overall yield of 72% and a 3.5-fold increase of the specific lipase activity. The developed process offers a great potential for an economic production of Lip2 at large scale in Y. lipolytica LgX64.81.

Temperature dependence of mycosubtilin homologue production in Bacillus subtilis ATCC6633

Bacillus subtilis ATCC6633 produces mycosubtilin, a non-ribosomally synthesized lipopeptide of the iturin family which presents antagonistic activities toward various phytopathogens. Different homologues with fatty acid moiety varying from C15 to C17 are usually co-produced, with their biological activities increasing with the number of carbons in the fatty acid chain. In the present report, we highlight that growth temperature modulates both the extent of mycosubtilin production and the relative abundance of the different homologues. A 30-fold increase in mycosubtilin production was observed when the temperature was decreased from 37 degrees C to 25 degrees C for both strain ATCC6633 and its derivative BBG100, a constitutive mycosubtilin overproducer. However, no significant difference in either the expression of the mycosubtilin synthetase encoding genes or in the intracellular synthetase concentration could be found, suggesting that the observed phenotype originated from a higher mycosubtilin synthetase turnover at lower temperature. We also point out that lower growth temperature leads to an increased proportion of odd-numbered fatty acid homologues as a consequence of de novo synthesis of C17 anteiso fatty acid following cell adaptation to low temperatures.

High performance microbiological transformation of L-tyrosine to L-dopa by Yarrowia lipolytica NRRL-143

Background

The 3,4-dihydroxy phenyl L-alanine (L-dopa) is a drug of choice for Parkinson's disease, controlling changes in energy metabolism enzymes of the myocardium following neurogenic injury. Aspergillus oryzae is commonly used for L-dopa production; however, potential improvements in ease of handling, growth rate and environmental impact have led to an interest in exploiting alternative yeasts. The two important elements required for L-dopa production are intracellular tyrosinases (thus pre-grown yeast cells are required for the transformation of L-tyrosine to L-dopa) and L-ascorbate, which acts as a reducing agent.

Results

Pre-grown cells of Yarrowia lipolytica NRRL-143 were used for the microbiological transformation of L-tyrosine to L-dopa. Different diatomite concentrations (0.5–3.0 mg/ml) were added to the acidic (pH 3.5) reaction mixture. Maximum L-dopa biosynthesis (2.96 mg/ml L-dopa from 2.68 mg/ml L-tyrosine) was obtained when 2.0 mg/ml diatomite was added 15 min after the start of the reaction. After optimizing reaction time (30 min), and yeast cell concentration (2.5 mg/ml), an overall 12.5 fold higher L-dopa production rate was observed when compared to the control. Significant enhancements in Y_p/s, Q_s and q_s over the control were observed.

Conclusion

Diatomite (2.0 mg/ml) addition 15 min after reaction commencement improved microbiological transformation of L-tyrosine to L-dopa (3.48 mg/ml; p ≤ 0.05) by Y. lipolytica NRRL-143. A 35% higher substrate conversion rate was achieved when compared to the control.

Characteristics of copper tolerance in Yarrowia lipolytica

We discovered that a mutant strain of the dimorphic yeast Yarrowia lipolytica could grow in the yeast form in high concentrations of copper sulfate. The amount of metal accumulated by Y. lipolytica increased with increasing copper concentrations in the medium. Washing with 100 mM EDTA released at least 60% of the total metal from the cells, but about 20-25 micromol/g DW persisted, which represented about 30% of the soluble fraction of cultured cells. The soluble fraction (mainly cytosol) contained only about 10% of the total metal content within cells cultured in medium supplemented with 6 mM copper. We suggest that although a high copper concentration induces an efflux mechanism, the released copper becomes entrapped in the periplasm and in other parts of the cell wall. Washing with EDTA liberated not only copper ions, but also melanin, a brown pigment that can bind metal and which located at the cell wall. These findings indicated that melanin participates in the mechanism of metal accumulation. Culture in medium supplemented with copper obviously enhanced the activities of Cu, Zn-SOD, but not of Mn-SOD.

Yeast as an efficient biocatalyst for the production of lipid-derived flavours and fragrances

Responding to consumer' demand for natural products, biotechnology is constantly seeking new biocatalysts. In the field of hydrophobic substrate degradation, some yeast species known some years ago as non-conventional, have acquired their right to be considered as good biocatalysts. These Candida, Yarrowia, Sporobolomyces ... are now used for themselves or for their lipases in processes to produce flavours and fragrances. In this paper we present some examples of use of these biocatalysts to generate high-value compounds and discuss the new trends related to progress in the development of molecular tools or the mastering of the redox characteristics of the medium.

Influence of Glucose and Saturated Free-Fatty Acid Mixtures on Citric Acid and Lipid Production by Yarrowia lipolytica

In the present report, the effect of glucose and stearin (substrate composed by saturated free-fatty acids) on the production of biomass, reserve lipid, and citric acid by Yarrowia lipolytica ACA-DC 50109 was investigated in nitrogen-limited cultures. Numerical models that were used in order to quantify the kinetic behavior of the above Yarrowia lipolytica strain showed successful simulation, while the optimized parameter values were similar to those experimentally measured and the predictive ability of the models was satisfactory. In nitrogen-limited cultures in which glucose was used as the sole substrate, satisfactory growth and no glucose inhibition occurred, although in some cases the initial concentration of glucose was significantly high (150 g/l). Citric acid production was observed in all trials, which was in some cases notable (final concentration 42.9 g/l, yield 0.56 g per g of sugar consumed). The concentration of unsaturated cellular fatty acids was slightly lower when the quantity of sugar in the medium was elevated. In the cases in which stearin and glucose were used as co-substrates, in spite of the fact that the quantity of cellular lipid inside the yeast cells varied remarkably (from 0.3 to 2.0 g/l-4 to 20% wt/wt), de novo fatty acid biosynthesis was observed. This activity increased when the yeast cells assimilated higher sugar quantities. The citric acid produced was mainly derived from the catabolism of sugar. Nevertheless, citric acid yield on sugar consumed and citrate specific production rate, as evaluated by the numerical model, presented substantially higher values in the fermentation in which no fat was used as glucose co-substrate compared with the cultures with stearin used as co-substrate.

Methyl Oleate Modulates LIP2 Expression in the Lipolytic Yeast Yarrowia lipolytica

Methyl oleate was used as a primary carbon source and as an alternative inducer for the production of an extracellular lipase, Lip2, in Y. lipolytica strain LgX64.81 grown in a 20-l bioreactor. The lipase-encoding gene, LIP2, was investigated during culture on methyl oleate using a pLIP2-LacZ reporter fusion and we provide evidence for the involvement of methyl oleate in its regulation.

Selection of new over-producing derivatives for the improvement of extracellular lipase production by the non-conventional yeast Yarrowia lipolytica

The non-conventional yeast Yarrowia lipolytica produces an extracellular lipase encoded by the LIP2 gene. Mutant strains with enhanced productivity were previously obtained either by chemical mutagenesis or genetic engineering. In this work, we used one of these mutants, named LgX64.81 to select new overproducing strains following by amplification of the LIP2 gene. We also developed a process for lipase production in bioreactors and compared lipase production levels in batch and fed-batch cultures. Batch culture led to a lipase production of 26450 U ml(-1) in a media containing olive oil and tryptone as carbon and nitrogen sources. Feeding of a combination of tryptone and olive oil at the end of the exponential growth phase yielded to lipase activity of 158246 U ml(-1) after 80 h of cultivation. In addition this production system developed for the extracellular lipase could also be applied for other heterologous protein production since we have demonstrated that LgX64.81 is an interesting alternative host strain.

Identification and characterisation of LIP7 and LIP8 genes encoding two extracellular triacylglycerol lipases in the yeast Yarrowia lipolytica

In the lipolytic yeast Yarrowia lipolytica, the LIP2 gene was previously reported to encode an extracellular lipase. The growth of a Deltalip2 strain on triglycerides as sole carbon source suggest an alternative pathway for triglycerides utilisation in this yeast. Here, we describe the isolation and the characterisation of the LIP7 and LIP8 genes which were found to encode a 366 and a 371-amino acid precursor protein, respectively. These proteins which belong to the triacylglycerol hydrolase family (EC 3.1.1.3) presented a high homology with the extracellular lipase CdLIP2 and CdLIP3 from Candida deformans. The physiological function of the lipase isoenzymes was investigated by creating single and multi-disrupted strains. Lip7p and Lip8p were found to correspond to active secreted lipases. The lack of lipase production in a Deltalip2 Deltalip7 Deltalip8 strain suggest that no additional extracellular lipase remains to be discovered in Y. lipolytica. The substrate specificity towards synthetic ester molecules indicates that Lip7p presented a maximum activity centred on caproate (C6) while that of Lip8p is in caprate (C10).