Potato Glucose Research Articles

Cyclodextrin glycosyltransferase production by new Bacillus sp. strains isolated from brazilian soil.

Three strains of Bacillus sp. (BACRP, BACNC-1 and BACAR) were isolated from soil adhered to cassava husk. CGTase specific activity for the three isolated strains was higher when cultivated at 40°C. Potato starch, cassava starch, maltodextrin and glucose were used as carbon source and growth temperatures varied from 25 to 55°C. The three isolates presented higher CGTase specific activity when cultivated with potato starch at 40°C. Isolated BACRP and BACAR presented specific activity of 4.0×10–3 and 2.2×10–3 U/mg prot at pH 7.0, respectively, when cultivated in mediums added with NaCl 2%; at pH 10,0 their activities were of 3.4×10–3 and 3.0×10–3 U/mg prot, respectively, in the same concentration of NaCl. On the other hand, the isolated BACNC-1 presented activity specific of 2.4×10–3 U/mg prot when cultivated at pH 7.0 added of NaCl 1%, and at pH 10.0 the specific activity was of 3.4×10–3 U/mg prot without NaCl addition. This work also showed the presence of cyclodextrins formed during fermentation process and that precipitation with acetone or lyophilization followed by dialysis was efficient at removing CDs (cyclodextrins), thus, eliminating interference in the activity assays. The enzyme produced by the BACAR strain was partially purified and β-CD was liberated as a reaction product.

Selective conversion of plasma glucose into CO2 by Saccharomyces cerevisiae for the measurement of 13C abundance by isotope ratio mass spectrometry: proof of principle

AbstractTo study carbohydrate digestion and glucose absorption, time‐dependent 13C enrichment in plasma glucose is measured after oral administration of naturally occurring 13C‐enriched carbohydrates. The isotope enrichment of the administered carbohydrate is low (APE <0.1%) and plasma 13C glucose measurements are routinely determined with gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) or liquid chromatography/combustion/isotope ratio mass spectrometry (LC/C/IRMS). In this study, plasma glucose was converted into CO2 by an in‐tube reaction with yeast permitting direct measurement of 13CO2 in the headspace. Saccharomyces cerevisiae incubated under anaerobic conditions was able to convert sufficient glucose into CO2 to produce a consistent CO2 peak in IRMS with little variation in peak area and precise δ13CPDB values for corn glucose: −11.40 ± 0.16‰, potato glucose: −25.17 ± 0.13‰, and plasma glucose: −26.29 ± 0.05‰. The measurement showed high linearity (R2 = 0.999) and selectivity and was not affected by the glucose concentration in the tested range of 5–15 mM. Comparison with GC/C/IRMS showed a good correlation of enrichment data: R2 > 0.98 for both sources of glucose and plasma samples. Commercially available, instant dried baker's yeast was qualitatively and quantitatively comparable with freshly prepared yeast: R2 > 0.96, slope 1.03 and 1.08 for glucose solutions and plasma, respectively. Thus, yeast conversion of plasma glucose into CO2 and 13C measurement applying a breath 13CO2 analyzer is an inexpensive, simple and equally accurate alternative to the more expensive and laborious GC/C/IRMS and LC/C/IRMS measurements. Copyright © 2007 John Wiley & Sons, Ltd.

Effect of multiple factors on accumulation of nucleosides and bases in Cordyceps militaris

In order to improve the accumulation of valuable metabolites (3′-deoxyadenosine, adenosine, guanosine, cytidine, uridine, adenine and uracil) in Cordyceps militaris, multiple factors such as carbon sources, nitrogen sources, metal ions and fermentation duration were investigated in liquid shake flasks. Using both potato broth and glucose as carbon sources were found to facilitate the production of nucleosides and bases most, and 2% of glucose was the most suitable initial level. Mixture of 0.3% yeast extract with 0.3% peptone was the best selection of nitrogen sources and supplementing with 0.1 mmol/L Mn 2+ achieved the maximum biomass and biosynthesis of nucleosides and bases among all investigated metal ions. The most suitable harvest time for C. militaris was found to be the 6th day, because the production of 3′-deoxyadenosine, adenosine and uridine began to speed up from the later exponential growth phase until the 6th day. Finally, under optimal culture conditions, the contents of 3′-deoxyadenosine, adenosine, guanosine, cytidine, uridine, adenine and uracil were increased to 0.212 ± 0.014 mg/g, 5.05 ± 0.31 mg/g, 4.03 ± 0.30 mg/g, 0.556 ± 0.029 mg/g, 6.39 ± 0.33 mg/g, 0.208 ± 0.016 mg/g and 0.437 ± 0.027 mg/g, respectively.

Trichophyton eboreumsp. nov. Isolated from Human Skin

An unusual dermatophyte was isolated from the plantar scales of a human immunodeficiency virus-positive man with tinea pedis. Morphology, physiology, and molecular data provided evidence to support the new species Trichophyton eboreum. This dermatophyte is characterized by rapid growth on common mycological media, a flat powdery off-white colony, formation of clavate microconidia, smooth- and thin-walled cylindrical or club-shaped macroconidia with two to nine cells, the presence of hook-shaped hyphae, the production of cleistothecium-like structures and spiral hyphae in older cultures, positive hair perforation, the absence of pigmentation on potato glucose agar, the absence of a requirement for vitamins, a weak positive urease reaction, no growth at 37 degrees C, resistance to 5% NaCl, resistance to fluconazole, good growth on human epidermal keratin, and the production of various enzymes on different media by the API-ZYM test. More than 5% divergence from any known species of dermatophyte was revealed by sequence analysis of the internal transcribed spacer of the rRNA gene.

P.3.077 The prognostic of schizophrenia and atypical antipsychotics

In order to improve the accumulation of valuable metabolites (3′-deoxyadenosine, adenosine, guanosine, cytidine, uridine, adenine and uracil) in Cordyceps militaris, multiple factors such as carbon sources, nitrogen sources, metal ions and fermentation duration were investigated in liquid shake flasks. Using both potato broth and glucose as carbon sources were found to facilitate the production of nucleosides and bases most, and 2% of glucose was the most suitable initial level. Mixture of 0.3% yeast extract with 0.3% peptone was the best selection of nitrogen sources and supplementing with 0.1 mmol/L Mn2+ achieved the maximum biomass and biosynthesis of nucleosides and bases among all investigated metal ions. The most suitable harvest time for C. militaris was found to be the 6th day, because the production of 3′-deoxyadenosine, adenosine and uridine began to speed up from the later exponential growth phase until the 6th day. Finally, under optimal culture conditions, the contents of 3′-deoxyadenosine, adenosine, guanosine, cytidine, uridine, adenine and uracil were increased to 0.212 ± 0.014 mg/g, 5.05 ± 0.31 mg/g, 4.03 ± 0.30 mg/g, 0.556 ± 0.029 mg/g, 6.39 ± 0.33 mg/g, 0.208 ± 0.016 mg/g and 0.437 ± 0.027 mg/g, respectively.

P.3.076 Bifeprunox: a novel atypical antipsychotic with in vivo 5-HT1A receptor agonistic activity

In order to improve the accumulation of valuable metabolites (3′-deoxyadenosine, adenosine, guanosine, cytidine, uridine, adenine and uracil) in Cordyceps militaris, multiple factors such as carbon sources, nitrogen sources, metal ions and fermentation duration were investigated in liquid shake flasks. Using both potato broth and glucose as carbon sources were found to facilitate the production of nucleosides and bases most, and 2% of glucose was the most suitable initial level. Mixture of 0.3% yeast extract with 0.3% peptone was the best selection of nitrogen sources and supplementing with 0.1 mmol/L Mn2+ achieved the maximum biomass and biosynthesis of nucleosides and bases among all investigated metal ions. The most suitable harvest time for C. militaris was found to be the 6th day, because the production of 3′-deoxyadenosine, adenosine and uridine began to speed up from the later exponential growth phase until the 6th day. Finally, under optimal culture conditions, the contents of 3′-deoxyadenosine, adenosine, guanosine, cytidine, uridine, adenine and uracil were increased to 0.212 ± 0.014 mg/g, 5.05 ± 0.31 mg/g, 4.03 ± 0.30 mg/g, 0.556 ± 0.029 mg/g, 6.39 ± 0.33 mg/g, 0.208 ± 0.016 mg/g and 0.437 ± 0.027 mg/g, respectively.

First Report of Pathogenic Association Between Fusarium graminearum and Soybean.

Fusarium graminearum, a pathogen of wheat and corn, was reported recently as a saprophytic fungus colonizing soybean (Glycine max L. Merr.) fruits and seeds at R7 in Argentina (2). To evaluate the capacity of F. graminearum obtained from stem and seeds of symptomatic soybean plants that cause disease on soybean seedlings, isolates were obtained during the 2001 to 2002 growing season from: (i) the basal one-third of stems from field-grown soybean plants, collected at R5, with light brown external and internal discoloration and leaves with interveinal chlorosis; and (ii) soybean seeds with pink tegument. The pathogen was isolated on potato glucose agar acidified with 0.2% lactic acid (PGAA). Isolates were identified as F. graminearum on the basis of growth rate and pigmentation of colonies on PGAA, lack of microconidia (1), and morphology and size of typical macroconidia in sporodochia developed on Spezieller Nährstoffarmer Agar (3). Isolates of F. graminearum, CE135 and CE136 (from wheat) and CE137 (from corn) deposited in the Centro de Referencia en Micología (CEREMIC), Fac. Farmacia y Bioquímica, UNR, Argentina, were used as references in identifying the soybean isolates. Plants (14-day-old) were inoculated separately with stem and seed isolates in the greenhouse at 26 ± 2 and 20 ± 2°C day/night temperature by inserting a piece of mycelium into a wound made with a scalpel in the hypocotyl. A completely randomized block design (RCB) was utilized with four replicate pots with four plants per pot. Plants wounded but without mycelium served as controls. This test was conducted twice (experiments 1 and 2). Another test was completed by burying a thin layer of wheat caryopsis colonized by fungal mycelium of the stem isolate CE170 in the soil of pots. Plants in pots with soil without inoculum served as controls (4). The experiment was conducted twice (experiments 3 and 4) in an RCB with five replications, four plants per replication. The progress of symptoms in experiments 1 and 2 were stem with light brown discoloration around the inoculation point that extended progressively along the stem, interveinal chlorosis or loss of turgence of unifoliate leaves, and interveinal chlorosis of trifoliate leaves followed by plant wilting and death. Twenty-one days after inoculation, average percentages of dead plants (%DP) was 42 and 21% for stem and seed isolates, respectively. For experiments 3 and 4, %DP was 56%, 45 days after emergence. These plants had roots with light brown, necrotic areas. Control plants remained healthy. The pathogen was reisolated from the stem (100%) and root (57%) tissues of symptomatic plants but not from similar tissues of control plants. To our knowledge, this is the first report of a pathogenic relationship between F. graminearum and soybean.

Exopolysaccharides and capsules in human pathogenic Exophiala species - Exopolysaccharide und Kapseln bei humanpathogenen Exophiala-Arten

Summary. The black yeasts Exophiala spinifera and E. dermatitidis produce extracellular slimes, which may be either in the form of a well-delimited capsule or of diffusely exuded exopolysaccharides (EPS). The optimal conditions for their production were studied. The presence or absence of polysaccharide material can be used for recognition of the two species. Five-day-old cultures grown on potato glucose agar at 24 � C were observed in India ink, and positive identification for E. spinifera was obtained when significant halos were seen around yeast cells. In contrast, E. dermatitidis had irregular EPS with a fibrillar substructure made visible by alcian blue staining. Other Exophiala species produce insignificant amounts of extracellular mucus or none at all. The diagnostic method is particularly useful with yeast-like primary cultures, which often consist entirely of budding cells and lack the characteristic structures of the filamentous Exophiala synanamorph.

Recent Outbreak of Soybean Stem Canker Caused by Diaporthe phaseolorum var. caulivora in the Main Soybean-Producing Region of Argentina.

The first report of soybean stem canker (SSC) caused by Diaporthe phaseolorum var. caulivora in South America was published in 2001, and was based on an isolate obtained in 1999 at Oliveros, Santa Fe (32°33'S, 60°51'W), Argentina (2). During the 2001 to 2002 growing season, isolates of D. phaseolorum var. caulivora were obtained from stems of field-grown soybeans (Glycine max L.) exhibiting SSC symptoms. Isolates were collected in three localities of the main soybean-producing region of Argentina: Marcos Juárez, Córdoba (32°66'S, 62°10'W); Salto, Buenos Aires (34°20'S, 60°33'W); and Diego de Alvear, Santa Fe (34°21'S, 62°10'W), and disease incidence in the fields was 10 to 60%, 5 to 15%, and 10 to 20%, respectively. The pathogen was isolated on potato glucose agar acidified with 0.2% lactic acid cultured in the dark at 25 ± 1°C. White colonies with compact and tufted mycelium were produced and turned yellow and light tan after 6 days. Appressed and fluffy mycelia were observed in old cultures. Stromata (2 mm diameter) were produced but pycnidia were not detected. After 20 days in culture at 25 ± 1°C under a 12-h light and 12-h dark regime, clustered perithecia developed on stem segments. For each isolate, 10 perithecia, 90 asci, and 30 bicellular, biguttulate ascospores were measured. Averages of asci length and width were 28.3 ± 2.3 and 5.9 ± 0.7 μm, respectively. Averages of ascospores mean length and width were 8.4 ± 0.6 and 2.5 ± 0.4 μm, respectively. These measures were similar to the measures obtained previously (2). Based on these features, the new isolates were classified as D. phaseolorum var. caulivora (Athow & Caldwell). Clustered perithecia, smaller asci and ascospores, and the development of fluffy mycelia with age were the main characteristics that distinguished D. phaseolorum var. caulivora from D. phaseolorum var. meridionalis (1). Pathogenicity trials were performed on cvs. Tracy M, Crockett, Hutchenson, and RA 702 in the greenhouse by placing a small amount of mycelium in soybean seedling hypocotyls wounds made with a scalpel. The pathogen was reisolated from stem portions of the symptomatic plants. Control plants remained healthy. The results reported here show that D. phaseolorum var. caulivora is widely disseminated in the main soybean-producing region of Argentina, where it coexists with D. phaseolorum var. meridionalis (2). The coexistence of both varieties indicates pathogen variability in the region is higher than previously recognized.

Optimization of in vitro growth conditions of Pyrenophora teres for production of the phytotoxin aspergillomarasmine A

In liquid cultures of Pyrenophora teres, three phytotoxins may be found: L, L - N -(2-amino-2-carboxyethyl) aspartic acid (toxin A), anhydroaspergillomarasmine A (toxin B) and aspergillomarasmine A (toxin C). In particular, toxins A and C cause chlorotic and necrotic symptoms in detached barley leaves, toxin C being the most damaging, whereas toxin B is only weakly phytotoxic. When P. teres is grown in liquid modified Fries medium, toxin B is the main toxin accumulated, possibly due to a ring closure of toxin C at the low pH value of the medium. The amount of toxin B produced by 11 isolates of P. teres was compared in modified Fries medium. Generally, the most virulent isolates of P. teres produced higher amounts of toxin B than the less virulent isolates. During growth, the pH of the media decreased from 6.7 to about 3.0–3.5, followed by a slight increase to about 3.5–4.0. All isolates, except one, produced toxin B, whereas only two isolates produced toxin C and toxin A. Maintaining the pH at about 6.5 by sterile titration with 1M NaOH resulted in a shift in toxin accumulation from toxin B to toxin C. The addition of tris or phosphate buffer to the media resulted in higher pH during the growth period, an increase in the total amount of toxins produced, and a shift in toxin accumulation from toxin B to toxin C. The higher pH value probably prevented the conversion of toxin C into toxin B. No toxins were produced in two routinely used media, potato glucose broth and grass broth. Toxin B and toxin C were purified by ion exchange chromatography and precipitation with HCl.

Cerebriform colonies of Paracoccidioides brasiliensis isolated from nine-banded armadillos (Dasypus novemcinctus) at room temperature.

Twelve isolates of Paracoccidioides brasiliensis generated cerebriform colonies at room temperature on potato glucose agar slants (PDA). These isolates contained abundant chlamydospores and yeast-like cells and are a subset of the 65 isolates obtained from nine-banded armadillos (Dasypus novemcinctus). They grew as a yeast form with typical multiple buddings at 37 degrees C on brain heart infusion agar supplemented with 1% glucose. After replating on PDA and culturing at room temperature for 2 months, the mutants appeared as cottonous colonies, which indicated that the morphological characteristics were unstable.

Indole-3-Acetic Acid, Glucose, and Inoculum Influence the Formation and Distribution of Basidiocarps of Pholiota malicola in Culture

Combinations of light, glucose, 10-4 or 10-3 M indole-3-acetic acid (IAA), and the developmental stage of the inoculum influenced the growth in culture of Pholiota malicola. Vegetative inoculum formed basidiocarps on potato glucose agar (PDA) only with 3 or 4%, and not with 1 or 2% glucose unless IAA was added. In the light on 2% glucose in PDA, using either whole or parts of immature or mature basidiocarps as inoculum, basidiocarps formed and IAA increased their size and numbers. When the cap was used as inoculum its orientation, pileus up or down, determined whether the basidiocarps formed were solitary, in a cluster or scattered. In the dark using all of the aforementioned types of inoculum, IAA promoted the growth of a mass of vegetative mycelium at the inoculation point and enlargement of carpophore parts, but new basidiocarps did not develop.

Indole-3-acetic acid, glucose, and inoculum influence the formation and distribution of basidiocarps of Pholiota malicola in culture

Combinations of light, glucose, 10-4 or 10-3 M indole-3-acetic acid (IAA), and the developmental stage of the inoculum influenced the growth in culture of Pholiota malicola. Vegetative inoculum formed basidiocarps on potato glucose agar (PDA) only with 3 or 4%, and not with 1 or 2% glucose unless IAA was added. In the light on 2% glucose in PDA, using either whole or parts of immature or mature basidiocarps as inoculum, basidiocarps formed and IAA increased their size and numbers. When the cap was used as inoculum its orientation, pileus up or down, determined whether the basidiocarps formed were solitary, in a cluster or scattered. In the dark using all of the aforementioned types of inoculum, IAA promoted the growth of a mass of vegetative mycelium at the inoculation point and enlargement of carpophore parts, but new basidiocarps did not develop.

First Report on Pathogenic Variability of Different Isolates of Diaporthe phaseolorum var. meridionalis on Soybean in Argentina.

The objective of this study was to characterize the pathogenicity of several local isolates of Diaporthe phaseolorum (Cooke & Ellis) Sacc. var. meridionalis Fernández and its anamorph, Phomopsis phaseoli (Desmaz.) Sacc. meridionalis Morgan-Jones, the causal agent of southern stem canker of soybean (Glycine max (L.) Merr.), in soybean lines carrying major resistance genes. Soybean plants with typical stem canker symptoms were collected during the 1996 to 1997 and 1997 to 1998 growing seasons in the central and southern areas of Santa Fe Province, Argentina. The pathogen was isolated from the internal tissues of infected stems, cultured on potato glucose agar acidified with 0.2% lactic acid (APGA), amended with streptomycin at 100 mg/liter, and maintained in the dark at 25 ± 1°C. Isolates were characterized based on the morphology of colonies, perithecia, and pycnidia and measurement of asci, bicellular, biguttulate ascospores, and alpha conidia (1). Soybean cultivars used to assay pathogenicity included Tracy M (Rdc1 and Rdc2 genes), Isoline I (Tracy Misoline with only the Rdc1 gene), Isoline II (Tracy M isoline with only the Rdc2 gene), Crockett (Rdc3 gene), Hutchinson (Rdc4 gene), and RA 702 (susceptible cultivar). Hypocotyls of 14-day-old seedlings grown in the greenhouse were inoculated by the toothpick method. Four replicates of nine seedlings each were used. Seedlings punctured with sterile toothpicks served as controls. The experiment was repeated twice with similar results. The D. phaseolorum var. meridionalis isolates assayed and their collection locations were Dpm1 (Malabrigo), Dpm2 (Los Molinos), Dpm3 (San Justo), Dpm5 (Oliveros), Dpm6 (San Jerónimo), and Dpm7 (Clarke). Twenty-eight days after inoculation, stem canker reactions were measured as the percentage of dead plants. The pathogen was reisolated from stems of randomly chosen symptomatic plants on day 14 after inoculation. These plants were included in the calculation of the percentage of dead plants. In control plants, lesions were not detected, and mycelial growth did not occur from stem portions plated on APGA. Tracy M and RA 702 had 0 to 7% dead plants and 70 to 95% dead plants, respectively, with all assayed isolates. Cultivars with single resistance genes reacted differently to various isolates. Isolates Dpm1 and Dpm3 caused little or no stem canker (<10% dead plants) on all cultivars with resistance genes. Isolates Dpm2 and Dpm6 killed 56 and 52%, respectively, of Isoline II (Rdc2 gene) plants. Isolates Dpm2 and Dpm7 killed 25% of cv. Hutchinson (Rdc4 gene) and Isoline I (Rdc1 gene) plants, respectively. Isolate Dpm5 killed <12% of plants with genes Rdc1, Rdc2, or Rdc3. The reaction of isolate Dpm5 with Hutchinson (Rdc4 gene) was not evaluated. The pathogenic diversity of these isolates of D. phaseolorum var. meridionalis may have been induced by the wide diffusion of resistant host cultivars (2).

Coimmobilized aerobic/anaerobic mixed cultures in shaked flasks

The freely suspended aerobic fungus, Aspergillus awamori, and the anaerobic bacterium, Zymomonas mobilis were cultivated in synthetic medium in a stirred tank reactor. Their immobilized monocultures and coimmobilized mixed cultures were cultivated in shaked flasks in synthetic medium on various substrates. The biological variables of the freely suspended and immobilized monocultures were determined on soluble potato starch, maltose and glucose as substrates, respectively. In the coimmobilized mixed culture the fungus, which grows in the outer aerobic shell and the surface of the beads, converts the starch and maltose to glucose. Glucose is consumed by both of the microorganisms. Z. mobilis growing in the anaerobic core of the beads, converts a part of glucose to ethanol. The influence of the spore concentration of the fungus, bacterial inoculum amount and the kind of substrate on the cell growth and ethanol formation were evaluated. Repeated batch cultivation was maintained for 200 h.

Distinction of biovar 2 strains of Agrobacterium from other chromosomal groups by differential acid production

Biovar (bv) 2 strains of Agrobacterium produced more acid from glucose than strains from the other two biovars This property caused the development of a clear zone around bv-2 colonies growing on potato glucose agar supplemented with 0.8% calcium carbonate. This simple cultural test produced results after 2 d at 28°C, and distinguished all 22 bv-2 strains tested from strains of other chromosomal groups of Agrobacterium; none of the 42 bv-1 and 16 bv-3 strains tested produced a clear zone around their colonies.

Effects of dietary carbohydrates on growth and body components of the giant freshwater prawn,Macrobrachium rosenbergii

The availability of various dietary carbohydrate sources for juvenile giant freshwater prawn, Macrobrachium rosenbergii , was evaluated according to weight gain and body composition. Different carbohydrate sources, α -potato starch, soluble starch, dextrin, sucrose, glucose and glycogen were separately included in a purified diet. After 60 days the greatest weight gain was achieved in the groups fed potato starch or soluble starch. The group receiving glucose as the carbohydrate source had low weight gain. Food conversion efficiency and the protein efficiency ratio were higher in the group receiving soluble starch as the dietary carbohydrate source. Muscle lipid consisted mainly of phospholipids and partial glycerides; midgut gland lipids were composed of triglycerides and phospholipids. A change in dietary carbohydrates had a minor influence on muscle lipid levels but caused variations in lipid class composition of the midgut gland. Comparatively high levels of free fatty acids and phospholipids were found in the midgut gland of groups fed soluble starch and potato starch, respectively. No major differences in fatty acid compositions were apparent. Soluble starch and potato starch were efliciently utilized by the prawn as dietary carbohydrate sources.

Intracellular activity of mycelial proteinases during fruit-body development in Flammulina velutipes

In the mycelium of Flammulina velutipes cultured on potato–glucose solution the concentration of water-soluble protein began to decrease steeply before fruit bodies formed, but the total amount of protein per culture decreased only when fruit bodies began to elongate rapidly. The level remained very low during rapid elongation. Proteinase activity per unit weight of mycelium against milk protein and azoalbumin decreased in parallel with the concentration of mycelial protein. Activity against azure blue – hide powder was low until the onset of rapid fruit-body elongation and reached a maximum later during that phase. Azoalbumin was hydrolyzed more actively than hide powder. Proteolytic activity per gram of mycelium against mycelial protein was almost the same before fruiting as during rapid fruit-body elongation. Specific activities per milligram protein against the three types of nonnative substrates increased in parallel to a maximum late during rapid elongation when protein concentration was lowest. Specific activity against native mycelial protein was also higher in extracts from older mycelia. Proteolysis was optimal near neutral pH and very low at pH 3.2. Tests with group-specific proteinase inhibitors showed that metallo-proteinases predominate in the mycelium. Serine, and to a lesser extent carboxyl and thiol proteinases, were also present. Neither endogenous inhibitors nor activators of proteolysis were detected.

Mating behaviour ofKeratinomyces ceretanicuswithArthroderma uncinatum

Keratinomyces ceretanicus was described as a new taxon distinct from Trichophyton ajelloi. Because of the morphological similarity between the two species, their mating behaviour was studied. The optimum temperature for growth of K. ceretanicus was found to be 25 degrees C rather than 17 degrees C. The type culture produced moderate numbers of microconidia on potato glucose agar after 2 weeks at 25 degrees C and a large number of smooth, thick-walled, cylindro-fusiform, 7-to 12-celled macroconidia. On Sabouraud glucose agar containing chloramphenicol and cycloheximide growth was partially but not completely inhibited. When crossed on a soil-hair medium, K. ceretanicus produced fertile gymnothecia typical of Arthroderma uncinatum with 10 (-) mating type isolates of A. uncinatum. As a result, it is concluded that K. ceretanicus is a facultative synonym of T. ajelloi.

Ineffective Cleaning of Polysulfone Ultrafiltration Membrane Systems and Corrosion by Bisulfite Used as a Sanitizer

Bisulfite solution was used to sanitize polysulphone ultrafiltration membranes. The ultrafiltration system consisted of a 380-L jacketed vat with agitator, prefilter, centrifugal pump, and two polysulphone ultrafiltration membranes in parallel with valves and pressure gauges before and after the membranes. The system was soiled by recycling 380L of sweet whey (40°C) for 2.0h followed by concentrating (by diverting permeate steam to drain) whey for .5h. The cleaning cycle consisted of acid cleaner (.5h, 40°C) followed by enzyme cleaner (10.0h, 40°C) and rinsing (2.0h, 40°C). A .2% sodium metabisulfite solution was circulated for 5min and the ultrafiltration unit left idle overnight. Swabs and rinse water samples were taken immediately after soiling, after cleaning, and the next morning to check sanitizing. Samples were plated on plate count agar and potato glucose agar (acidified with tartaric acid to pH 3.5) to determine numbers of bacteria, yeasts, and molds. Effectiveness of bisulfite was pH dependent. At pH 4.7, bisulfite solution was ineffective in controlling microorganisms and at pH 3.5, bisulfite was microstatic. Compared with trials with Antibac B (30ppm Cl), bisulfite (pH 3.5) was similar for controlling bacteria, yeasts, and molds. Extensive corrosion of stainless steel housings was apparent following long-term contact (2 wk) with bisulfite solution. Laboratory trials using stainless steel fittings, plates, and rubber gaskets found that extensive corrosion and pitting of stainless steel and leaching of gaskets by bisulfite solution required several conditions: low pH, exposure to bisulfite vapors, use of 304 type stainless steel, and oxygen. Intermittent or continuous exposure to acidic bisulfite vapors resulted in corrosion. Antibac B (30ppm Cl) did not show similar corrosion or leaching effects.