Candida Bombicola ATCC Research Articles

Screening yeasts for the stereoselective reduction of oxoester clofibrate analogues

Reduction of oxoesters 1b– d and 1f, g in the presence of different yeast strains ( Saccharomyces cerevisiae DSM 11285, S. cerevisiae CBS 7336, Cryptococcus curvatus ATCC 20509, Candida bombicola ATCC 22214, Trigonopsis variabilis DSM 70714, Kluyveromyces marxianus CBS 6556) affords hydroxy esters 2b– d and 2f, g with diastereoisomeric excesses (de) up to >99%. Hydrolytic enzyme(s) contained in the yeasts catalyzed to some extent the hydrolysis of the oxoesters to the corresponding acids, which undergo decarboxylation followed by reduction of the carbonyl moiety.

The effect of medium composition on the structure and physical state of sophorolipids produced by Candida bombicola ATCC 22214

Candida bombicola was grown using a variety of lipophilic carbon substrates. Most of the hydrocarbon and carboxylic acid substrates resulted in a mixture of sophorolipids consisting of free acids and the more desirable lactones. The ratio of diacylated lactone to free acid in these mixtures was a maximum when produced using hexadecane and heptadecane. All of the other lipophilic substrates resulted in significant amounts of free acids being produced. These lactone products were unique in that they precipitated as crystals, which were easily separated from the culture medium. All of the other products were isolated as oils as is usually reported in the literature. Finally, the amounts of these crystals recovered were significantly higher than those observed for any of the oily products. It was possible to determine the degree of direct incorporation of the lipophilic substrates into the sophorolipids for a homologous series of alkanes. The amount of direct incorporation increased with increasing chain length to a maximum for pentadecane, hexadecane and heptadecane. As the length of the alkane substrate increased further, the amount of direct incorporation then decreased until there was no apparent incorporation for eicosane.

Oxygen transfer rate and sophorose lipid production by Candida bombicola.

Sophorose lipids (SLs) have applications as surfactants and are produced at high levels by several yeasts. We developed a fed-batch shake-flask method for the production of SLs by Candida bombicola ATCC 22214. Optimal aeration, expressed in terms of oxygen transfer rate, was between 50 and 80 mM O(2)/L h(-1) and resulted in maximum values for both volumetric product formation (1-1.5 g/L h(-1)) and SL yield (350 g/L). The lowest aeration levels resulted in the enrichment in saturated fatty acid SLs at the expense of unsaturated fatty acid SLs.

Sophorolipids: a source for novel compounds

Renewable resources, such as rapeseed oil or oleic acid, combined with glucose were used both in a feed-batch and two-stage continuous process for the production of sophorolipids with the yeast Candida bombicola ATCC 22214. High yields >300 g l −1 and increased productivities of 57 g l −1 d −1 (feed-batch) and 76 g l −1 d −1 (continuous mode), respectively, were obtained by using optimized cultivation conditions. The key-factors for enhanced sophorolipid production are presented. The acidic sophorolipid was used for further modification after alkaline hydrolysis and purification. A novel glucoselipid was synthesized by using the enzyme naringinase (EC 3.2.1.40). A (ω-1)-hydroxyfatty acid, commercially not yet available and difficult to prepare by organic synthesis, was released by acidic hydrolysis, purified and is proposed as a precursor for plastics and flavours.

Production of sophorolipids from whey: development of a two-stage process with Cryptococcus curvatus ATCC 20509 and Candida bombicola ATCC 22214 using deproteinized whey concentrates as substrates

In order to produce sophorolipids from whey, thereby lowering the lactose content and biological oxygen demand, a two-step batch cultivation process was developed including medium sterilization by filtration. In the first step, whey was sterilized by a combination of crossflow and sterile filtration. Because the sophorolipid-producing yeast Candida bombicola ATCC 22214 was not able to use lactose as a carbon source directly, the oleaginous yeast Cryptococcus curvatus ATCC 20509 was grown on deproteinized whey concentrates (DWC). With 1:1 diluted DWC-20, lactose was consumed as the carbon source and biomass (24 g/l dry weight content) as well as single-cell oil (SCO, 10 g/l) were produced. The cultivation broth was disrupted with a glass bead mill and it served as medium for growth (29 g cell dry mass/l) and sophorolipid production (12 g/l) of the yeast C. bombicola.

Sophorolipid Production with High Yields on Whey Concentrate and Rapeseed Oil without Consumption of Lactose

Sophorolipids were produced by single-step batch cultivation of Candida bombicola ATCC 22214 on deproteinized whey concentrate and repeated feed of rapeseed oil. A mild sterilization method for whey was developed. High yields of 280 g dry sophorolipids l−1 were obtained from deproteinized whey concentrate containing 100 g lactose l−1 and 300 g rapeseed oil l−1. Surprisingly, the whey lactose was not consumed by the organism. Growth only on the oil was assumed and a high lipase activity of 24 U per g cell dry weight resulted.

Production of sophorolipids in high concentration from deproteinized whey and rapeseed oil in a two stage fed batch process using Candida bombicola ATCC 22214 and Cryptococcus curvatus ATCC 20509

High concentrations of 422 g sophorolipids l−1 were produced using a two-stage cultivation process: first deproteinized whey concentrate (DWC) containing 110 g lactose l−1 was used for cultivation of the yeast Cryptococcus curvatus ATCC 20509, resulting in 34 g dry weight l−1, 20 g single-cell oil l−1 and reducing the chemical oxygen demand (COD) from 159 g l−1 to 35 g oxygen l−1. Afterwards cells were disrupted by passing the cell suspension directly through a high pressure laboratory homogeniser. After autoclavation, the resulting crude cell extract containing the single-cell oil served as substrate for growth of Candida bombicola ATCC 22214 and for sophorolipid production in a second stage. When the single-cell oil was consumed, repeated feeding of 400 g rapeseed oil l−1 was started increasing the yield of sophorolipids to 422 g l−1. A simple technique for product isolation, sedimentation, could be used to harvest the crude sophorolipids. © Rapid Science Ltd. 1998

Kontinuierliche Produktion von Sophoroselipiden mit Candida bombicola ATCC 22214

AbstractSeit einigjr Zeit wild die Gewinnung von Sophoroselipiden aus nachwacnsenuen Rohstoffen mit Candida bornhicola untersueht. Schwerpunkt der Betrachtungen waren bisher Kultivierungen in Batch‐ oder Fed‐Batch‐Verfahren. Zur Produktion dicser Biotenside jmkontinuierhchen Prozeß sind bisher kaum Uniersuchungen vorbf fentlicht worden. Erste Ergebnissc zeigen jedoch, daß in kontinuierlicher Kultnr holie Produktivitäten erzielt werden können, die dieses Verfahren beziiglich dcrvorgenannten Mctlioden ?.u einerechten Alternative machen. Ein Verglcich beslehender Verfahren der Sophoioselipidproduklion and der kontinuierlichen Methode soil dies ver deutlichen.

Initial steps of sophoroselipid biosynthesis by Candida bombicola ATCC 22214 grown on glucose.

Candida bombicola ATCC 22214 produces the glycolipid sophoroselipid when cultivated on a medium with glucose as the sole carbon source. Under phosphate-limiting conditions the product yield rises from 0.033 to 0.143 and the specific product formation rate rises from 0.004 h-1 to 0.007 h-1. Enhanced sophoroselipid synthesis is initiated by the decline of the specific activities of NAD- and NADP-dependent isocitrate dehydrogenase (EC 1.1.1.41 and 1.1.1.42) to 2% and 0% of the initial activities respectively. Constantly high specific activity of citrate synthase (EC 4.1.3.7) causes an accumulation of isocitrate and citrate in the mitochondria. Both acids are transported into the cytosol where citrate is cleaved by ATP: citrate lyase (EC 4.1.3.8) giving rise to acetyl-CoA, the precursor of fatty acid synthesis. The ATP: citrate lyase is unaffected by different energy charges; the apparent K(m) values for coenzyme A, ATP and citrate are 23 microM, 250 microM and 256 microM respectively. NADPH for fatty acid synthesis might be generated by further metabolism of oxaloacetate, the other product of the citrate-cleaving reaction, by oxidation of the isocitrate by the cytosolic NADP-dependent isocitrate dehydrogenase or via the hexose monophosphate shunt. A possible explanation for sophoroselipid formation during exponential growth is given.

Influence of substrate supply on the production of sophorose lipids by Candida bombicola ATCC 22214

Candida (Torulopsis) bombicola ATCC 22214 produces 180 g/l sophorose lipids using glucose and oleic acid (technical grade) as combined substrates in an extended fed-batch cultivation. Excess of oleic acid generated a paste-like product. However, only when oleic acid was not detectable during the whole run of cultivation, a microcrystalline product precipitated. The unsaturated C-18 fatty acids of the technical grade oleic acid were transferred unchanged into the sophorose lipid.

Occurrence of fatty alcohol oxidase in alkane-and fatty-acid-utilising yeasts and moulds

Preparations of membrane fractions from 16 yeasts and three moulds were assayed for long-chain fatty alcohol oxidase (FAOD) activities after being grown on hexadecane or glucose and, in nine cases, on oleic acid. The enzyme was usually repressed in glucose-grown cells but in Candida bombicola ATCC 22 214 and Debaryomyces hansenii NCYC 33 appeared to be constitutive. Highest activities occurred in C. tropicalis and D. polymorphus (about 0.8 unit/mg protein) grown on hexadecane. Growth of yeasts on oleic acid partially induced FAOD activity but not with the moulds. In two strains of Yarrowia lipolytica (DSM 3286 and CBS 2076) no activity of FAOD was found but this could have been due to the known photo-lability of the enzyme. FAOD from different species shared similar characteristics with respect to substrate specificity and pH optimum.

Petite mutants of sophorolipid‐producing Candida yeasts

Treatment of both Candida apicola IMET 43747 and Candida bombicola ATCC 22214 with N-methyl-N'-nitro-N-nitroso guanidine resulted in formation of auxotrophic mutants and cytochrome oxidase negative mutants. The deficiency of intact cytochrome oxidase did not affect the ability to produce sophorose lipid. This indicates that intact mitochondrial energy supplying system is not necessary for the production of the extracellular sophorose lipids by both Candida yeasts.

Evidence for two fatty alcohol oxidases in the biosurfactant-producing yeast Candida (Torulopsis) bombicola

Fatty alcohol oxidase activities in Candida (Torulopsis) bombicola ATCC 22214, which produces large amounts of glycolipids consisting of omega- and (omega-1)-hydroxyfatty acids and a sugar moiety, occurred only in the microsomal fraction whether the cells had grown on n-alkanes, carbohydrates or a mixture of the two. High activities occurred in glucose-grown cells. Aliphatic alcohols from octanol to hexadecanol were oxidized with two maxima in activities for decanol and for tetradecanol. Differences in their pH optima and in temperature stability suggest two separate enzymes are present. Long chain diols, but not omega-hydroxyfatty acids, were also oxidized.