Strains Of Geotrichum Candidum Research Articles

Production of vitamin B12 via microbial strains isolated from marine and food sources in Egypt

Background Vitamin B12 is a very important water-soluble vitamin, which was first isolated from the liver as an anti-pernicious anemia factor. The sole source of vitamin B12 is the animal-based food. It has a complicated structure and requires expensive multi-steps to be synthesized chemically. Intriguingly, vitamin B12 can be produced through microbial fermentation by microorganisms in a cheap and more effective manner. Objective This study aims to isolate and characterize microorganisms that have the capability to produce vitamin B12. In addition, the current work aims to optimize the vitamin B12 production conditions by isolating strains using suitable waste materials to obtain a high vitamin B12 yield. Materials and methods Different bacterial and yeast isolates were isolated from marine and food samples using the pour-plate technique. These isolates were screened for vitamin B12 production using a specific growth medium that lacked vitamin B12 and a test indicator bacterium. The content of vitamin B12 was estimated using spectrophotometer measurement and high-performance liquid chromatography (HPLC). The isolates that showed high vitamin B12 productivity were identified using MALDI-TOF technique. The identified strains were implemented for the optimization of vitamin B12 production to reveal the most proper and optimum conditions for the production. Response surface methodology (RSM) was employed to enhance the production of vitamin B12 in a flask scale. Agro-industrial wastes such as molasses were used for vitamin B12 production using the most optimum conditions as determined by RSM. Results and conclusion Eighty-seven actinomycetes, bacterial, and yeast isolates were screened for vitamin B12 production. Out of these isolates, 15 showed high vitamin B12 productivity. We found that bacilli and yeast isolates were the most productive among the tested cocci and actinomycetes isolates. The highly productive Bacillus and yeast isolates were identified using the MALDI-TOF analysis. The isolates were identified as Candida pelliculosa, Geotrichum candidum, Bacillus subtilis and Bacillus sp. One strain of Candida pelliculosa (coded BYI), three strains of Geotrichum candidum (coded as MZYC, MZYD, and MZYG) were selected for studying the effect of sugar type and inoculum size on the yield of vitamin B12 production. Strain MZYD was selected for the statistical modelling using RSM to optimize seven factors for the vitamin B12 production. These factors included temperature, fermentation time, salt concentration, pH, sugar concentration, inoculum size, and aeration. Five factors i.e., temperature, pH, sugar concentration, and inoculum size were shown to significantly improve the vitamin B12 production. A maximum yield of 64.21 μg/100 ml was obtained using the optimized RSM conditions. These optimized conditions were used to produce vitamin B12 using molasses as a raw material for the microbial growth.

Identification of novel totiviruses from the ascomycetous fungus Geotrichum candidum.

Mycoviruses are widely distributed across the kingdom Fungi, including ascomycetous yeast strains of the class Saccharomycetes. Geotrichum candidum is an important fungal pathogen belonging to Saccharomycetes and has a diverse host range. Here, we report the characterization of four new classical totiviruses from two distinct Geotrichum candidum strains from Pakistan. The four identified viruses were tentatively named "Geotrichum candidum totivirus 1, 2, 3a, and 3b" (GcTV1-3b). The complete dsRNA genomes of the identified totiviruses are 4621, 4592, 4576, and 4576 bp in length, respectively. All totivirus genomes have two open reading frames, encoding a capsid protein (CP) and an RNA-dependent RNA polymerase (RdRP), respectively. The downstream RdRP domain is assumed to be expressed as a CP-RdRP fusion product via -1 frameshifting mediated by a heptameric slippery site. Sequence comparisons and phylogenetic analysis showed that each of the discovered viruses belongs to a new species of the genus Totivirus in the family Totiviridae, with GcTV1 and GcTV3 (a and b strains) clustering in one subgroup and GcTV2 in another subgroup.

ASSESSMENT OF PAINT-PIGMENT DEGRADING MICROORGANISMS FROM PAINT INDUSTRIES EFFLUENT-CONTAMINATED SITES IN ABA, SOUTH-EAST NIGERIA

The potential of microorganisms isolated from paint industry effluent-polluted soils to degrade the constituents of the effluents and contaminant removal efficiency after the remediation period were evaluated. Samples were collected from six different paint industries in Aba. Samples from the various paint industries reveals sample F showed the highest bacterial plate counts of 6.21±0.20 x 104cfu/g while samples B and D had the least bacterial counts of 1.30±0.20 x 104cfu/g and 1.30±0.31 x 104cfu/g respectively. The fungal counts of the polluted soils indicates sample D as having the highest count of 2.30±0.24 x 104cfu/g while sample A had the least count of 1.00±0.30 x104cfu/g. Total Paint Utilizing Fungal (TPUF) counts ranges from 1.23±0.02 x 104cfu/g to 3.45±0.10 x 104cfu/g and showed a significant difference between sample C and the control (p<0.05). The bacterial isolates from the contaminated soil include Pseudomonas spp., Escherichia coli, Citrobacter spp., Klebsiella spp., Proteus spp., Enterobacter spp., Providencia rettgeri, Shigella flexneri, Staphylococcus spp., Streptococcus spp. and Enterococcus spp. while the fungal isolates include Saccharomyces cerevisiae, Rhodotorula species, Rhizopus species, Aspergillus niger, Aspergillus flavus and Penicillum notatum. The counts of actual paint utilizing fungi were relatively lower than the heterotrophic groups. The paint degrading microorganisms isolated from the paint industry effluent polluted soils include paint effluent bacterial degraders: Pseudomonas spp. (33.3%), Escherichia coli(33.3%),, Citrobacter spp. (25%), Klebsiella spp.(25%), Proteus spp.(25%), Enterobacter spp.(12.5%). and Providencia rettgeri(12.5%), While the fungal paint effluent degraders include Geotrichum candidum(33.3%), Pichia kudriavzevii(33.3%), Fusarium sp.(25%), Aspergillus niger(25%), Penicillium funiculosum(25%) and Mucor sp.(12.5%). Geotrichum candidum strain GAD1 (MN63874.1) and Pichia kudriavzevii strain (MK811096.1) showed highest degrees of growth indicated by high turbidities during the screening test. This study showed that majority of the Indigenous organisms has the ability to utilize paints as their sole carbon source hence are the major bioremediating agents in the sampling areas.

Modelling the Radial Growth of Geotrichum candidum: Effects of Temperature and Water Activity.

Modelling the growth of microorganisms in relation to environmental factors provides quantitative knowledge that can be used to predict their behaviour in foods. For this reason, the effects of temperature and water activity (aw) adjusted with NaCl on the surface growth of two isolates and one culture strain of Geotrichum candidum were studied. A dataset of growth parameters obtained from almost 600 growth curves was employed for secondary modelling with cardinal models (CMs). The theoretical minimal temperature resulting from the modelling of the mycelium proliferation rate ranged from −5.2 to −0.4 °C. Optimal and maximal temperatures were calculated and found to have narrow ranges of 25.4 to 28.0 °C and 34.2 to 37.6 °C, respectively. Cardinal aw values associated with radial growth (aw min from 0.948–0.960 and aw opt from 0.992–0.993) confirmed the salt sensitivity of the species. Model goodness-of-fit was evaluated by the coefficient of determination R2, which ranged from 0.954 to 0.985, and RMSE, which ranged from 0.28 to 0.42. Substantially higher variability accompanied the lag time for growth modelling than the radial growth rate modelling despite the square root transformation of the reciprocal lag phase data (R2 = 0.685 to 0.808). Nevertheless, the findings demonstrate that the outputs of growth modelling can be applied to the quantitative evaluation of the roles of G. candidum in fresh cheese spoilage as well as the ripening of Camembert-type cheeses or various artisanal cheeses. Along with validation, the interactions with lactic acid bacteria can be included to improve the predictions of G. candidum in the future.

Retraction for Polev et al., "Draft Genome Sequence of Geotrichum candidum Strain 3C".

Volume 2, no. 5, e00956-14, 2014, [https://doi.org/10.1128/genomeA.00956-14][1]. We retract this article. The Geotrichum candidum strain 3C was initially identified and classified in the early 1970s (N. A. Rodionova, N. A. Tiunova, R. V. Feniksova, T. I. Kudriashova, and L. I. Martinovich, Dokl Akad

English

Four batches of Armada semi-hard goat cheese were elaborated from pasteurized milk inoculated with a natural starter culture, constituted of two lactococci strains, combined with a Geotrichum candidum strain. The four G. candidum strains tested as co-starter were selected for their proteolytic and lipolytic activities. The effects of an autochthonous starter on physico-chemical, microbiological and sensorial characteristics during the ripening of this cheese were evaluated. The depth of proteolysis was very low, which confirms the presence of low-level aminopeptidase activity. Fungal population was involved in lipolysis. The cheeses elaborated with G. candidum strains developed a desirable flavour characteristic of goat cheese and a creamy texture. Cheeses from batch I (that included the strain of G. candidum with high lipolytic activity and low proteolytic activity) presented a hardness profile that differed from the others, as it was the batch with the highest scores at thirty days of ripening and was even the best evaluated at the end of ripening because of their odour, fresh balanced pleasant taste and creamy smooth texture. Key words: Cheese, starter culture, Geotrichum candidum, lactic acid bacteria.

Mycelium-bound lipase from a locally isolated strain of Geotrichum candidum.

Mycelium-bound lipase (MBL), from a locally isolated Geotrichum candidum strain, was produced and characterized as a natural immobilized lipase. A time course study of its lipolytic activity in 1 L liquid broth revealed the maximum MBL activity at 4 h for mycelium cells harvested after 54 h. The yield and specific activity of MBL were 3.87 g/L dry weight and 508.33 U/g protein, respectively, while less than 0.2 U/mL lipase activity was detected in the culture supernatant. Prolonged incubation caused release of the bound lipase into the growth medium. The growth pattern of G. candidum, and production and properties of MBL were not affected by the scale. The stability of mycelia harboring lipase (MBL), harvested and lyophilized after 54 h, studied at 4 °C depicted a loss of 4.3% and 30% in MBL activity after 1 and 8 months, while the activity of free lipase was totally lost after 14 days of storage. The MBL from G. candidum displayed high substrate selectivity for unsaturated fatty acids containing a cis-9 double bond, even in crude form. This unique specificity of MBL could be a direct, simple and inexpensive way in the fats and oil industry for the selective hydrolysis or transesterification of cis-9 fatty acid residues in natural triacylglycerols.

Research of Producing Single Cell Protein with Molasses Wastewater

This paper is to study the optimum conditions for extracting the protein feed by using the mixed microbial fermentation. And using the single factor and orthogonal methods, the microbial content as the main indicators, investigated the effects of the combination of strain, strain ratio, the amount of bacteria, fermentation temperature, the concentration of fermentation, fermentation pH, nitrogen sources and inorganic salts and other factors on the fermentation of protein yield. The test results showed that the best fermentation process is sterilization process, the best combination of strains of Geotrichum candidum, Candida tropicalis and Candida utilis yeast, the cast of bacteria was 10%, the best molasses fermentation concentration 20g / 100 mL, and temperature 30 ° C, initial pH 5.0, appropriate amount of Yeast extract, magnesium sulfate, potassium dihydrogen phosphate and super phosphate. The Test provides a theoretical and experimental basis for Molasses wastewater utilization

Aromatic amino acids as precursors of antimicrobial metabolites inGeotrichum candidum

Geotrichum candidum ATCC 204307 was previously found to generate phenyllactic acid (PLA) and indoleacetic acid (ILA) in complex culture media. In this study, a relationship between concentrations of PLA, ILA, and hydroxy PLA (OH-PLA) and initial concentrations of phenylalanine, tryptophan, and tyrosine, added respectively as unique sources of nitrogen in synthetic medium, was established. Phenylpyruvic acid (PPA), an intermediate compound of PLA metabolism, was able to induce not only PLA but also phenylethyl alcohol (PEA) production when used separately as initial substrate. Under pH, temperature, and salt concentrations used for cheese-making, phenylalanine was found to be the most efficient substrate for antimicrobial metabolite production. In excess of substrate, different yeast strains of Geotrichum candidum, Yarrowia lipolytica, Candida natalensis, and Candida catenulata were shown here to produce 1.6 ± 0.5-5.0 ± 0.2 mM of PLA from phenylalanine, 5.0 ± 0.1-10.9 ± 0.3 mM of ILA from tryptophan, and 1.3 ± 0.3-7.0 ± 0.02 of PLA and 0.1 ± 0.0-2.22 ± 0.09 mM of PEA from PPA. Geotrichum candidum ATCC 204307 was the highest producer. This is the first time these antimicrobial metabolites PLA, OH-PLA, ILA, and PEA are being reported as the reaction products of aromatic amino acids catabolism in G. candidum.

Genetic diversity of dairy Geotrichum candidum strains revealed by multilocus sequence typing

The introduction of multilocus sequence typing (MLST) for strain characterization provided the first sequence-based approach for genotyping many fungi, leading to reproducible, reliable, and exchangeable data. A MLST scheme based on the analysis of six housekeeping genes was developed for genotyping Geotrichum candidum. The scheme was first developed using 18 isolates for which the complete sequences of the alanyl-tRNA synthetase (ALA1), pyruvate kinase (CDC19), acetyl-coA acetyltransferase (ERG10), glutaminyl-tRNA synthase (GLN4), phosphoglucoisomerase (PGI1), and phosphoglucomutase (PGM2) housekeeping genes were determined. Multiple sequence alignments of these genes were used to define a set of loci showing, as closely as possible, the same phylogenetic resolution level as complete gene sequences. This scheme was subsequently validated with 22 additional isolates from dairy and non-dairy sources. Overall, 58 polymorphic sites were indexed among 3,009 nucleotides analyzed. Depending on the loci, four to eight alleles were detected, generating 17 different sequence types, of which ten were represented by a single strain. MLST analysis suggested a predominantly clonal population for the 40 G. candidum isolates. Phylogenetic analysis of the concatenated sequences revealed a distantly related group of four isolates. Interestingly, this group diverged with respect to internal transcribed spacers 1 (ITS1), 5.8S, and ITS2 analysis. The reproducibility of the MLST approach was compared to random amplification of microsatellites by PCR (RAM-PCR), a gel profiling method previously proposed for G. candidum strain typing. Our results found MLST differentiation to be more efficient than RAM-PCR, and MLST also offered a non-ambiguous, unique language, permitting data exchange and evolutionary inference.

Thermal Alkaline Method to Prepare Geotrichuam Candidum Protein Foaming Agent

Geotrichum Candidum strain numbered 2.0498 was used as raw material. The Geotrichum Candidum thallus were collected through inoculation and shaking cultivation. Thermal alkaline method was applied for hydrolyzing Geotrichum Candidum mycoprotein to prepare protein foaming agent. The effect of bacteria concentration, Ca(OH)2mass concentration, hydrolysis temperature and hydrolysis time on foam expansion were studied. The optimization strategy was single factor test and subsequent response surface analysis based on Box-Behnken design. The results showed that the optimized condition were a bacteria concentration of 5.4%(w/v) and a Ca(OH)2mass concentration of 1.5%(w/v), at a hydrolysis temperature of 95°C for 4.1 h. Under these optimal conditions, the foam expansion was 28.1. Compared with the model theory prediction, the relative error was 0.46%. At the same time, a multiple quadratic regression equation between Geotrichum Candidum mycoprotein foam expansion and impact factors was setted up and it played an important role in predicting the foam expansion.

Technological characterization of Geotrichum candidum strains isolated from a traditional Spanish goats’ milk cheese

Forty-one strains of Geotrichum candidum isolated from Armada cheese, Sobado variety, were screened for their enzymatic activities, including proteolytic and lipolytic activities and aminopeptidase activity. The highest extracellular proteolytic activity was detected for 8 strains with values ranging between 2.086 and 4.685 mM Gly L−1 of milk. Extracellular lipolytic activity was high for all but one of the G. candidum strains, with values ranging between 67 and 131 μmol oleic mL−1. Cell-bound lipase activity showed values which were considerably lower than those for extracellular activity, ranging between 32.50 and 42.50 μmol oleic mL−1 and falling below 20 μmol oleic mL−1 in 28 strains. Aminopeptidase activity was not very high in the cell-free extract (CFE) of any of the strains, showing the highest values toward the substrate Lys-p-nitroanilide, with levels of activity ranging between 6.12 and 10.05 UE mg−1 protein in 8 strains. In accordance with the results obtained, four G. candidum strains were selected as co-cultures in order to study their role in the ripening of a semi-hard goat’s milk cheese.

Relationship between growth behaviour, micro and macroscopic morphologies and freezing sensitivity of the ripening starterGeotrichum candidumis strain specific and mostly related to the morphotypes: the arthrospores/hyphae parameter

Microscopic conformation, growth behaviour and freezing sensitivity of seven strains of Geotrichum candidum, a ripening starter, were studied and compared according to their macroscopic morphotypes. It has been shown that the thallus forming units (TFU)×ml-1/OD600nm ratio as a function of time is an interesting parameter to follow G. candidum sporulation through the growth behaviour. Microscopic conformation, growth behaviour and freezing sensitivity are clearly strain specific and mostly related to their corresponding morphotypes "yeast", "mould" or "intermediate". The two "mould" strains that sporulate weakly (UCMA103, UCMA499) showed a low survival rate to freezing stress whereas the "yeast" strains expressed a significant resistance owing to the arthrospore abundance. Interestingly, one strain (UCMA96) which appeared on solid medium in accord with the "mould" morphotype respond similarly to freezing stress.

Kinetics of an extracellular exo-inulinase production from a 5-flourocytosine resistant mutant of Geotrichum candidum using two-factorial design

In the present study, eight different strains of Geotrichum candidum were isolated and screened for an extracellular exo-inulinase production using chemically enriched sucrose–mineral media. The isolate (Zool-3i) with a better enzyme activity (1.38 IU/ml) was subjected to induced mutagenesis using methyl methane sulphonate (MMS) and a mutant with an enzyme activity of 32.06 IU/ml was obtained. Further exposure to ethyl methane sulphonate (EMS) and ultraviolet (UV) radiations yielded a mutant exhibiting an improved activity of 39.34 IU/ml. The potential mutant was cultured overnight and plated on 5fc–YPR agar medium and thus made resistant against 5-flourocytocine. Over 50-fold enhancement in enzyme production (71.85 IU/ml) was achieved when the process parameters including incubation period (48 h), sucrose concentration (5.0 g/L), pH (6.0), inoculum size (2.0%, 16 h old) and urea (0.2%) were identified using Plackett–Burman design. On the basis of kinetic variables, notably Q p (0.723 U/g/h), Y p / s (2.036 U/g) and q p (0.091 U/g cells/h), the mutant MEU-5fc-6 was found to be a hyper producer of exo-inulinase ( HS, LSD 0.045, p ⩽ 0.05).

Fatty acid preference of mycelium-bound lipase from a locally isolated strain of Geotrichum candidum.

Mycelium-bound lipase (MBL) was prepared using a strain of Geotrichum candidum isolated from local soil. At the time of maximum lipase activity (54h), the mycelia to which the lipase was bound were harvested by filtration and centrifugation. Dry MBL was prepared by lyophilizing the mycelia obtained. The yield of MBL was 3.66g/l with a protein content of 44.11mg/g. The lipase activity and specific lipase activity were 22.59 and 510U/g protein, respectively. The moisture content of the MBL was 3.85%. The activity of free (extracellular) lipase in the culture supernatant (after removal of mycelia) was less than 0.2U/ml. The MBL showed selectivity for oleic acid over palmitic acid during hydrolysis of palm olein, indicating that the lipase from G. candidum displayed high substrate selectivity for unsaturated fatty acid containing a cis-9 double bond, even in crude form. This unique specificity of MBL could be a direct, simple and inexpensive way in the fats and oil industry for the selective hydrolysis or transesterification of cis-9 fatty acid residues in natural triacylglycerols.

Identification and Characterisation of A Locally Isolated Lipolytic Microfungus - Geotrichum candidum

A strain of Geotrichum candidum was successfully isolated from local soil samples and some of its characteristics determined. The strain produces lipase that hydrolysed palm olein on a selective agar incorporated with Nile Blue sulphate and palm olein. Suspension culture was used to study the growth and lipolytic activity. The results showed that the highest dry cell mass of G. candidum was achieved after 96 hours of growth when 2% (v/v) seed culture was used as inoculum. Using spore suspension as an inoculum was not favourable since less yield of mycelia mass was obtained at peak of log phase and the culture exhibited relatively low lipolytic activity and efficiency of hydrolysis. The maximum amount of free fatty acids (90.5%) was released after 48 hours of incubation. However, the highest lipolytic activity, 7.02 mmole FFA/g dry cell was detected at 54 hours. The production of cell-bound lipase of G. candidum was concomitant with growth and declined when growth ceased. During the course of growth, changes to palm olein added into the culture medium caused the growth culture to turn in to a creamy colloidal emulsion. Towards the end of the incubation period, solid fatty particles were formed. Thin layer chromatographic analysis showed that triacylglycerols in the palm olein were rapidly hydrolysed to fatty acids in 18 hours, with no pronounced change in the amounts of 1,2-diacylglycerols and 1,3-diacylglycerols.

Olive-mill wastewaters: a promising substrate for microbial lipase production

The present study investigated the valorization of olive-mill wastewater (OMW) by its use as a possible growth medium for the microbial production of extra-cellular lipase. To this end, strains of Geotrichum candidum (NRRL Y-552 and Y-553), Rhizopus arrhizus (NRRL 2286 and ISRIM 383), Rhizopus oryzae (NRRL 6431), Aspergillus oryzae (NRRL 1988 and 495), Aspergillus niger (NRRL 334), Candida cylindracea (NRRL Y-17506) and Penicillium citrinum (NRRL 1841 and 3754, ISRIM 118) were screened. All strains were able to grow on the undiluted OMW, producing extra-cellular lipase activity. C. cylindracea NRRL Y-17506 showed the highest lipase activity on all the typologies of OMW used. Its lipase production on OMW was markedly affected by the type of nitrogen source and was induced by the addition of olive oil. The highest activity (9.23 IU ml −1) of the yeast was obtained on OMW supplemented with NH 4Cl (2.4 g l −1) and olive oil (3.0 g l −1).

Enantioselective properties of induced lipases from Geotrichum

Production of lipase by three strains of Geotrichum candidum (DBM 4012, DBM 4013, DBM 4166) and one strain of Geotrichum ludwigii (DBM 48) in liquid medium was investigated under addition of olive oil, which has been used as activator of the activity. The activity of cell-bound and extracellular lipases was determined. The most remarkable growth of the cell biomass was also observed using a medium with peptone as a source of nitrogen. The highest specific activity of all activated lipases was found when the cell growth reached a constant level (stationary phase of growth). All activated lipases were used as biocatalysts of the hydrolytic resolution of racemic cis- or trans-isomers of 2-(4-methoxybenzyl)cyclohexyl acetates. Attention was paid to the stereochemical course of the reaction, i.e. to the determination of the optical purity of the products and, consequently, to the assignment of the absolute configuration and the determination of the conversion rate. The satisfactory results from the point of view of the chemical yields of the reaction and enantiomeric purity of the products were obtained when lipases from G. candidum DBM 4013 were used as biocatalysts of the hydrolysis of trans-isomer of 2-(4-methoxybenzyl)cyclohexyl acetate.

Effect of yeast and bacterial adjuncts on the CLA content and flavour of a washed-curd, dry-salted cheese

Three strains of Propionibacterium freudenreichii ssp. shermanii that converted free linoleic acid to conjugated linoleic acid (CLA) in laboratory media were used as adjunct strains, together with strains of Geotrichum candidum and Yarrowia lipolytica, to make a dry-salted, washed-curd cheese. Lactobacillus fermentum was included to produce ethanol (from lactose), a potential substrate for ethyl ester synthesis, while Lactobacillus rhamnosus was used to control the adventitious non-starter lactic acid bacteria population. The total (esterified plus free) level of CLA was similar in the control and experimental cheeses and remained unchanged over 4 months of ripening. Addition of linoleic acid-rich safflower oil to the cheese curd increased the concentration of free linoleic acid generated in the cheese but the CLA content did not change. Free linoleic acid was released by the yeast lipase(s) but there was no conversion to CLA. High concentrations of ethyl esters were produced in the cheeses made with added yeast, giving a fruity flavour.

Development and validation of a plate technique for screening of microorganisms that produce volatile sulfur compounds

Volatile sulfur compounds (VSCs) are of major importance for flavor development in foodstuffs such as cheeses. Such compounds originate from the amino acid l-methionine, which can be degraded to methanethiol (MTL), a common precursor to a variety of other VSCs. A plate assay based on double-layer petri dishes containing 5,5′-dithio-bis-2-nitrobenzoic acid (DTNB), a chemical used for the estimation of free thiols, in the upper layer provides an easy and reliable detection method for thiol-producing, cheese-ripening microorganisms. MTL production was quantitated by measuring the yellow–orange color intensity resulting from reaction with DTNB. Using this method, 18 Geotrichum candidum strains isolated from cheeses were compared, and the color intensity was found to be correlated with the production of microbial VSCs as measured by gas chromatographic analysis.