Glucose metabolism in the yeast Schwanniomyces castellii: role of phosphorylation site I and an alternative respiratory pathway.

Glucose metabolism in a Crabtree-negative yeast, Schwanniomyces castellii, and a cytochrome b-deficient mutant of this strain was investigated in chemostat culture. The wild-type and mutant strains exhibited the same behavior. Oxidative metabolism was observed when the substrate uptake rate (qS) was low.

Fatty hydroxamic acid biosynthesis in aqueous medium in the presence of the lipase-acyltransferase from Candida parapsilosis.

The lipase-acyltransferase from Candida parapsilosis has been shown to catalyze fatty hydroxamic acid biosynthesis in a biphasic lipid/aqueous medium. The substrates of the reaction were an acyl donor (fatty acid or fatty acid methyl ester) and hydroxylamine. The transfer of acyl groups from a donor ester to hydroxylamine (aminolysis) was catalyzed preferentially to the reaction of free fatty acids.

Contribution to the study of surface microflora on Cantal cheese.

Bacteria and mould were isolated from microflora of Cantal cheese rind. They were identified and the influence of pH, temperature and water activity on growth rate were studied. An equation for growth rate mu(h-1) relative to temperature is described according to a mathematical model.

Amide metabolism: a putative ABC transporter in Rhodococcus sp. R312.

The DNA sequence has been determined upstream of the amiE structural gene in the amidase operon of Rhodococcus sp. R312 and a new ORF (amiS2) identified. The amiS2 gene encodes a potential 206 amino acid (aa) protein containing a high proportion of hydrophobic residues.

Study of the amidase signature group.

Computer methods for database search, multiple alignment and cluster analysis indicated significant homology between amino-acid sequences of 21 amidases or amidohydrolases (EC 3.5). All of them were found to be involved in the reduction of organic nitrogen compounds and ammonia production.

Study of the delta 12-desaturase system of Lipomyces starkeyi.

The specific activity of the microsomal delta 12-desaturase system, which transforms oleic acid into linoleic acid, was about 16 pmol/min/mg protein. However, most of the total activity was nonsedimentable even after a 200000 x g centrifugation for 100 min. The study of various physicochemical parameters showed that this enzymatic complex, functioning optimally between pH 7 and 8, had low thermal stability.

Cloning and sequencing of the beta-glucosidase-encoding gene from Candida molischiana strain 35M5N.

We have isolated a gene (bgln) encoding beta-glucosidase (beta Glu) from a cosmid library of the yeast, Candida molischiana 35M5N. The nucleotide sequence of bgln and its flanking regions was determined. This gene was found to be composed of 2289 bp and 763 amino acid (aa) residues encoding an 83.

Fatty acid and carotenoid composition of Rhodotorula strains.

Lipid content and composition of fatty acids with 6-25 carbon atoms were studied on strains of the 13 pink or red yeast species belonging to the genus Rhodotorula. The total amount of lipid represented an average of 13% of the dry weight. The neutral and polar lipid fractions were analyzed separately.

Factors influencing ester synthesis catalysed in aqueous media by the lipase from Candida deformans (Zach) Langeron and Guerra.

The purified lipase from Candida deformans was shown to catalyse ester production in aqueous media by esterification of free fatty acids but not by alcoholysis. As the enzyme also catalysed ester hydrolysis, the influence of various physico-chemical factors on ester hydrolysis and synthesis was studied and compared. Substrate specificities were also studied.

Sizing of the Rhodococcus sp. R312 genome by pulsed-field gel electrophoresis. Localization of genes involved in nitrile degradation.

The two restriction enzymes AsnI and DraI were found to produce DNA fragment sizes that could be used for mapping the Rhodococcus sp. R312 (formerly Brevibacterium sp. R312) genome by pulsed-field gel electrophoresis.

Substrate specificity of the lipase from Candida parapsilosis.

Substrate specificity of the acyltransferase activity of the lipase (EC 3.1.1.

Karyotype studies on different strains of Candida molischiana by pulsed-field gel electrophoresis.

We used pulsed-field gel electrophoresis to compare the electrophoretic karyotype of a Candida molischiana mutant, de-repressed for beta-glucosidase production, with a wild-type strain and a reference strain. The chromosomal organization in this mutant yeast was found to be quite different. Hybridization patterns and the relative fluorescence of all bands indicated eight chromosomes in the mutant strain and seven in the other two.

A very stable beta-glucosidase from a Candida molischiana mutant strain: enzymatic properties, sequencing, and homology with other yeast beta-glucosidases.

We purified a beta-glucosidase from the mutant strain Candida molischiana 35M5N. Analysis of the kinetic properties of this enzyme did not show any differences between the previously purified wild-type enzyme and that of the mutant. Nevertheless, a study of the stability of the enzyme at different pH levels and temperatures showed the increase resistance of this protein.

Glucose metabolism, enzymic analysis and product formation in chemostat culture of Hanseniaspora uvarum.

The physiology of Hanseniaspora uvarum K5 was studied in glucose-limited chemostat cultures and upon glucose pulse. Up to a dilution rate of 0.28 h-1, glucose was completely metabolized in biomass and CO2.

Brevibacterium linens pBL33 and Rhodococcus rhodochrous pRC1 cryptic plasmids replicate in Rhodococcus sp. R312 (formerly Brevibacterium sp. R312).

The replication of two cryptic plasmids from Brevibacterium linens ATCC 9174 (pBL33) and Rhodococcus rhodochrous ATCC 4276 (pRC1) was investigated in Rhodococcus sp. R312 (formerly Brevibacterium sp. R312).

Functioning and regioselectivity of the lipase of Candida parapsilosis (Ashford) Langeron and Talice in aqueous medium. New interpretation of regioselectivity taking acyl migration into account.

The lipase of Candida parapsilosis catalyses the formation of esters in aqueous media. In addition, the hydrolytic activity of the enzyme has been described in a recent publication as being selective for the 2 position, which is extremely rare. These features led to deeper investigation of the functioning and regioselectivity of the lipase in a biphasic aqueous medium.

Remarks on the appearance of "violine" on Cantal cheese (a note).

A mould, Scopulariopsis brevicaulis was isolated from a Cantal cheese. This mould was responsible for the "violine" phenomenon. It's optimum pH growth was about 7 and the mould was able to grow suitably at 10 degrees C, the temperature of cellar for cheese ripening.

Purification and characterization of the endocellular beta-glucosidase of a new strain of Candida entomophila isolated from fermenting agave (Agave sp.) juice.

A yeast strain isolated in the laboratory from fermenting agave (Agave sp.) juice was studied and classified as Candida entomophila. The beta-glucosidase of this yeast was purified by ion-exchange chromatography and gel filtration.

Physiological approach to heterologous human serum albumin production by Kluyveromyces lactis in chemostat culture.

Production of recombinant human serum albumin (rHSA) controlled by the constitutive promoter phosphoglycerate kinase was studied in Kluyveromyces lactis. It was governed by both cell concentration and glycolytic flow. The triggering of the fermentation metabolism by unfavourable culture conditions (pH, pO2, D) caused a decrease in the synthesis of the heterologous protein.

Cloning of the wide spectrum amidase gene from Brevibacterium sp. R312 by genetic complementation. Overexpression in Brevibacterium sp. and Escherichia coli.

The amiE gene of Brevibacterium sp. R312 encoding wide spectrum amidase was isolated by complementation of a Brevibacterium sp. mutant using a plasmid gene bank of chromosomal DNA.

Application of high-performance liquid chromatography to the study of the biological transformation of adiponitrile.

A procedure for the assay of nitrile hydratase and amidase activity by high-performance liquid chromatography is described. The method can be used to assay the intermediate compounds resulting from the hydrolysis of adiponitrile into adipic acid, and to determine the kinetics of the hydrolysis of these compounds using whole cells and enzyme extracts. The precision of the method makes it suitable for the determination of the enzyme parameters: Km and Vm (nitrile hydratase and amidase).

Selection and study of a Candida molischiana mutant derepressed for beta-glucosidase production.

A mutant strain of Candida molischiana was selected. Analysis of the exocellular activity of Candida molischiana 35M5N grown on different carbon sources revealed that the biosynthesis of beta-glucosidase is derepressed in this yeast strain. The strain is not a hyper-producer mutant.

Study of the growth of yeasts from feta cheese.

The effects of various physicochemical parameters on the growth of three yeast strains were investigated, including: pH, sodium chloride content, water activity in the medium and temperature. All strains were unaffected by pH changes. Growth was optimal at pH 5.

Development of high-cell-density fermentation for heterologous interleukin 1 beta production in Kluyveromyces lactis controlled by the PHO5 promoter.

The use of a phosphate organic form taken up by Kluyveromyces lactis removes repression of the PHO5 promoter and releases heterologous interleukin 1 beta synthesis while providing sufficient phosphate for growth. The oxidative metabolism of high-cell-density fed-batch and chemostat cultures was thus maintained under derepressed protein synthesis conditions. Interleukin 1 beta production was then growth-associated, an unusual mode of protein synthesis regulation under the control of the PHO5 promoter.

Expression of a synthetic DNA region containing a consensus promoter and two lac operators in Brevibacterium sp.

The cat reporter gene was used to assess expression of two promoters, previously strongly expressed in Escherichia coli, in Brevibacterium sp. R312 strain. The tac promoter (de Boer et al.