Glucose Yeast Extract Agar Research Articles

Activité antifongique d'une souche d' Actinomadura d'origine saharienne sur divers champignons pathogènes et toxinogènes

Objective. – Study of the antifungal activity of an actinomycete strain AC 170 isolated from a Saharan palm grove soil collected at Adrar, South-West Algeria. Methods. – Based on morphological and chemical characteristics, the isolate studied was identified as Actinomadura sp. This strain grew only on the solid media. Antibiotic production was tested on five solid culture mediums. The GYEA (Yeast extract-glucose agar) and ISP1 (tryptone-yeast extract agar) media enabled satisfactory production. The butanolic extract was tested against 11 pathogenic and toxinogenic fungi including Candida albicans and seven Aspergillus species. Results. – The results showed a strong antifungal activity of the strains studied against all the species tested. Chromatographic bioassay revealed that the crude butanolic extract contained one active compound. Conclusion. – The UV–visible spectrum and the chromogenic reactions of this active compound suggested a non-polyenic nature and probably aromatic structure. Investigation of this molecule is now in progress.

Prevalence and characterization of Clostridium perfringens from spices in Argentina

Spices can present high microbial counts and Clostridium perfringens, Bacillus cereus, Salmonella and Shigella, among others have been isolated from spices. C. perfringens is an important pathogen agent causing, among other diseases, enteritis in humans caused by C. perfringens enterotoxin (CPE) which causes human food poisoning and enterotoxemia in domestic animals. The aims of the present work were (i) to establish the hygienic sanitary quality of some spices in San Luis, Argentina; (ii) to determine the presence of C. perfringens in these spices by means of the most probable number (MPN) and count on plate methods; (iii) to characterize the enterotoxigenic strains of C. perfringens by PCR and immunological methods such as reverse passive latex agglutination (RPLA) and (iv) to type by PCR C. perfringens strains isolated. A total of 115 samples of spices, 67 of which were purchased in local retail stores and 48 domestically collected were analysed. Total aerobe counts on tryptone glucose yeast extract agar medium of the 115 samples were between <10 and 10 6 CFU/g. The colifecal counts using Mac Conkey broth of the 115 samples were <4–10 3 CFU/g, with 28 samples (24.34%) exceeding the limit established by the Spanish Alimentary Code (10 CFU/g) while 2 samples (1.73%) had a sulfite reducing anaerobe load above standard limits. A total of 14 C. perfringens strains (12.17%) were isolated and characterized from 115 samples by the standard biochemical tests. Four of which (28.60%) turned out to be enterotoxigenic by PCR and RPLA. In order to type C. perfringens strains based on their main toxins, the 14 strains were analysed by PCR. All strains belonged to type A. All RPLA positive strains were cpe + by PCR. The percentage of enterotoxigenic strains was more elevated that those reported in other studies for this type of sample. These results indicate that sanitary conditions in different production stages of species must be improved to reduce health hazards. The high percentage (24.34%) of samples with colifecal values above standard limits is an indication of deficient sanitary conditions. These results suggest the need to provide legislation on the sanitary and hygienic quality of spices in our country.

Validation of the Official Control Method Based on Polymerase Chain Reaction (PCR) for Identification of Authorised Probiotic Yeast in Animal Feed

Council Directive 70/524/EEC regulates the application of probiotic (microorganisms) additives in feeding stuffs. In the present study a method for the differentiation and strain identification of authorised probiotic Saccharomyces cereviseae strains in feeding stuffs by Polymerase Chain Reaction (PCR) was validated. Four different samples of animal feeding stuffs containing yeast at levels between 10(5) to 10(7) CFU/g were examined. Samples were enumerated on chloramphenicol glucose yeast extract agar and colonies were selected from these plates for DNA extraction and subsequent analysis. The PCR method using delta sequence primers produced an 'amplified sequence polymorphism' characteristic for the test strain. Feeds supplemented with one of four probiotic yeast strains each were analysed by seven of nine invited laboratories. All laboratories returned valid results with the exception of one laboratory that had insufficiently separated bands on the gel. The method had a good reproducibility for probiotic yeast isolates from feed of all four authorised probiotic yeast strains (APYS) CBS 493.94, APYS CNCM 1-1079, APYS CNCM 1-1077, APYS NCYC SC47 and of a commercially available yeast reference strain, NCYC 81. The PCR method is to be considered by CEN and ISO as official control method for identification of authorised probiotic Saccharomyces cerevisiae strains from feeding stuffs.

Comparison of different media for isolation and enumeration of yeasts occurring in blue-veined cheese

Comparison of eleven selective media for detecting and enumerating foodborne yeasts in blue-veined cheese showed that rose bengal chloramphenicol agar (RBC), dichloran rose bengal chloramphenicol agar (DRBC), oxytetracycline gentamycin glucose yeast extract agar (OGGY) and dichloran 18% glycerol agar (DG18) were the most efficient. Other examined media failed to be suitable for either inhibiting bacteria and suppressing the spread of moulds or supporting the growth of all yeasts present. Significant differences (P≯0.05) were obtained on different media, however counts obtained were overlapping on three groups of media. Yeast extract eugenol agar (YEE) medium significantly differed from all others.

Comparison of selective media for the recovery and enumeration of probiotic yeasts from animal feed

Six selective media (acidified malt extract agar, CHROMagar Candida, dichloran rose bengal chloramphenicol, molybdate, oxytetracycline glucose yeast extract and Petrifilm Yeast and Mould agar) were examined for the recovery of three yeasts commonly used in animal feeds as probiotic additives ( Candida pintolopesii, C. saitoana and Saccharomyces cerevisiae). The highest recovery was obtained on oxytetracycline glucose yeast extract agar, although this was susceptible to overgrowth by moulds. CHROMagar Candida also gave good recovery and species were easily discriminated by the differential colour formation of colonies.

Presence and changes in populations of yeasts on raw and processed poultry products stored at refrigeration temperature

A study was undertaken to determine populations and profiles of yeast species on fresh and processed poultry products upon purchase from retail supermarkets and after storage at 5°C until shelf life expiration, and to assess the potential role of these yeasts in product spoilage. Fifty samples representing 15 commercial raw, marinated, smoked, or roasted chicken and turkey products were analyzed. Yeast populations were determined by plating on dichloran rose bengal chloramphenicol (DRBC) agar and tryptone glucose yeast extract (TGY) agar. Proteolytic activity was determined using caseinate and gelatin agars and lipolytic activity was determined on plate count agar supplemented with tributyrin. Populations of aerobic microorganisms were also determined. Initial populations of yeasts (log 10 cfu/g) ranged from less than 1 (detection limit) to 2.89, and increased by the expiration date to 0.37–5.06, indicating the presence of psychrotrophic species. Highest initial populations were detected in raw chicken breast, wings, and ground chicken, as well as in turkey necks and legs, whereas roasted chicken and turkey products contained less than 1 log 10 cfu/g. During storage, yeast populations increased significantly ( P≤0.05) in whole chicken, ground chicken, liver, heart and gizzard, and in ground turkey and turkey sausage. Isolates (152 strains) of yeasts from poultry products consisted of 12 species. Yarrowia lipolytica and Candida zeylanoides were predominant, making up 39 and 26% of the isolates, respectively. Six different species of basidiomycetous yeasts representing 24% of the isolates were identified. Most Y. lipolytica strains showed strong proteolytic and lipolytic activities, whereas C. zeylanoides was weakly lipolytic. Results suggest that yeasts, particularly Y. lipolytica, may play a more prominent role than previously recognized in the spoilage of fresh and processed poultry stored at 5°C.

Reduced susceptibility in laboratory-selected mutants of Aspergillus fumigatus to itraconazole due to decreased intracellular accumulation of the antifungal agent

To study the mechanism of resistance of Aspergillus fumigatus to itraconazole, spontaneous mutants with reduced susceptibility were selected by spreading 2×10 8 conidia from a clinical isolate (W73355) susceptible to miconazole (MIC 2 mg/l), itraconazole (MIC 0.25 mg/l) and amphotericin B (MIC 0.5 mg/l) on 40 peptone yeast extract glucose agar plates containing miconazole (32 mg/l). The 19 colonies that grew (frequency 0.95×10 −7) in the presence of miconazole were screened by broth macrodilution technique for their susceptibility to itraconazole. A total of two isolates (frequency 1×10 −8) MCZ14 and MCZ15 had MICs of 16 and 8 mg/l, respectively, for itraconazole. Both MCZ14 and MCZ15 showed concomitant increases in MICs for ketoconazole and miconazole, but not for amphotericin B. Growth inhibition studies as well as kill curve experiments revealed that MCZ14 and MCZ15 were less susceptible to itraconazole compared to the parental strain. The intracellular accumulation of itraconazole in A. fumigatus was time and concentration dependent. Maximum accumulation was obtained within 30 min at 5 μM itraconazole. In MCZ14 and MCZ15 intracellular accumulation of [ 3H]itraconazole was reduced by approximately 80 and 60%, respectively, compared to the susceptible parent. The respiratory inhibitor carbonyl cyanide m-chlorophenyl hydrazone at 200 μM reduced the intracellular accumulation of itraconazole by approximately 36.2% ( P≤0.05) in the parent and in the mutant strains. These results suggest that (i) the reduced accumulation of itraconazole in MCZ14 and MCZ15 is due to diminished permeability of the drug and perhaps not due to efflux, (ii) the uptake of itraconazole in A. fumigatus may be an energy dependent process, and (iii) decreased accumulation of itraconazole is at least in part responsible for the reduced susceptibility of the mutant isolates to itraconazole.

A collaborative study on media for the enumeration of yeasts in foods

A collaborative study was made to evaluate the effectivity of a general purpose medium, tryptone glucose yeast extract (TGY) agar on the detection and enumeration of yeasts from food. Nine laboratories participated in the study and compared five media (four kinds of TGY with different concentrations of glucose, one of them without tryptone, and, for comparison, dichloran rose bengal chloramphenicol (DRBC) agar). Six food samples were investigated by each laboratory and 23 additional food samples were investigated individually by different laboratories. No difference was found in the performance of media with either the samples common to all laboratories or the various samples tested in different ones. A medium consisting of tryptone, glucose and yeast extract, at any concentration of glucose tested, appeared reliable for the detection and enumeration of yeasts from foods, and its performance did not differ from that of DRBC. Omission of tryptone as recommended by ISO provided an even simpler medium of equally good performance. TGY without chloramphenicol may result in higher total counts due to the development of bacteria. DRBC incubated in light results in lower counts compared to that incubated in the dark.

Biolistic transformation of the human pathogenic fungus Coccidioides immitis

Coccidioides immitis is a fungal respiratory pathogen of humans. The infectious, saprobic phase of the microbe resides in soil of southwestern desert regions of the United States. The genetics of this pathogen are essentially undeveloped. Progress in studies of the molecular biology of C. immitis have been hampered by the absence of a transformation system. We report here the first stable integration of plasmid DNA into chromosomes of C. immitis by the method of biolistic DNA delivery. A previously-described pAN7-1 plasmid and a newly-constructed C. immitis URA5 gene disruptant (pU5H-1) were used to transform C. immitis strain 735. The 6.8-kilobase (kb) pAN7-1 plasmid and the 10.1-kb pU5H-1 construct both contained the hygromycin phosphotransferase gene ( hph) which encodes a protein that inactivates hygromycin B (HmB) by phosphorylation. Germinated, saprobic phase spores (arthroconidia) and parasitic phase cells (spherules) of C. immitis were subjected to bombardment by gold particles coated with either the linearized pAN7-1 or the circular pU5H-1 plasmid DNA (50 μg DNA per 25 mg gold particles). A single pAN7-1 and two pU5H-1 transformants were initially selected from approximately 10 7 cells on the basis of their ability to grow on glucose–yeast extract agar supplemented with 60–80 μg/ml HmB. The transformants showed resistance to HmB up to a concentration of approximately 320 μg/ml of media, compared to the parental strain which was unable to grow in the presence of 40 μg HmB/ml of media. Southern hybridization analyses of the transformants suggested that both the pAN7-1 and pU5H-1 DNAs were integrated into chromosomal DNA of C. immitis as tandem repeats. After animal passage, all transformants showed mitotic stability of the integrated DNA. This newly-developed transformation system permits genetic manipulations of C. immitis which were not previously possible.

In-vitro isolation and antifungal susceptibility of amphotericin B-resistant mutants of Aspergillus fumigatus.

Aspergillus fumigatus mutants resistant to amphotericin B were selected in the laboratory following UV irradiation. A total of 18 colonies (frequency 1.8 x 10(-7)) that grew in the presence of amphotericin B (8 mg/L and 16 mg/L) on peptone yeast extract glucose agar were tested for their susceptibility to amphotericin B, nystatin, azoles, and the echinocandin L-743872. Ten of the 18 isolates showed an eight-fold rise in amphotericin B MIC (4 mg/L) compared with the susceptible parent whereas the remaining isolates showed a 16 to 32-fold rise in amphotericin B MIC (8-16 mg/L). Subculturing of three representatives from each of the groups that had MIC values of 4 mg/L and 8-16 mg/L for six cycles revealed that the resistance trait was stably expressed. All amphotericin B-resistant isolates showed a significant level of cross-resistance to nystatin but not to azoles and L-743872. Kill-curve studies with amphotericin B revealed that the killing of the resistant isolates was significantly less than that of the susceptible parent strain. These results show that amphotericin B-resistant mutants of A. fumigatus can be isolated in the laboratory following a single-step UV-induced mutagenesis and suggest that similar mechanisms could operate in nature for the emergence of resistance in clinical isolates.

Mycoflora of paddy and milled rice produced in the region of Northeastern Argentina and Southern Paraguay

Thirty samples of paddy rice and twenty-five of milled rice were obtained from processing centers located in two northern Provinces of Argentina and one southern Province of Paraguay. Contaminating fungi were enumerated by direct plating on dichloran rose bengal chloramphenicol agar and oxytetracycline glucose yeast extract agar before and after surface disinfection. All fungi were isolated and identified to the genus level and percentage infection of samples calculated. Those belonging to the genera Penicillium, Aspergillus and Fusarium were identified to species level. The surface mycoflora was dominated by storage fungi, notably Penicillium citrinum (73% of samples), P. islandicum (60% of samples), Aspergillus niger, A. flavus and Fusarium semitectum. The major fungi found as internal contaminants of paddy rice were, again, Penicillium citrinum (66% of samples) and P. islandicum (50% of samples). Milled rice showed a lower level of contamination, but with a similar species distribution, Penicillium citrinum and P. islandicum again being the main contaminants. The presence of these species suggests a potential for mycotoxin production. Further studies are needed to establish the mycotoxin quality of rice from this region.

Optimisation of methodology for enumeration of xerophilic yeasts from foods

Xerophilic yeasts grow in intermediate moisture foods ( a w, 0.65–0.85) such as sugar syrups, fruit concentrates, jams and brines. Non-osmophilic yeasts are enumerated by diluting in 0.1% peptone and then plated onto media such as malt extract or glucose yeast extract agar. In the presence of moulds the yeasts are enumerated in dichloran rose bengal chloramphenicol agar (DRBC). These procedures were demonstrated to be unsatisfactory for the enumeration of xerophilic yeasts in low a w foods. Investigations using pure cultures of xerophilic yeasts as well as naturally contaminated apple juice concentrates and glacé cherries have shown that a reduced a w diluent, in particular 30% w/w glycerol in combination with tryptone 10% glucose yeast extract agar (TGY) optimises the recovery of the yeasts, especially sublethally injured cells. The inclusion of sodium chloride in either the diluents or the culture media was not necessary to optimise the recovery of D. hansenii growing in 20% sodium chloride broths.

Effect of water activity, modified atmosphere packaging and storage temperature on spore germination of moulds isolated from prunes

The combined effect of medium water activity ( a w) modified atmosphere packaging (MAP) on the conidial germination of Aspergillus niger, Eurotium amstelodami, Penicillium chrysogenum and Fusarium oxysporum was studied by applying response surface methodology (RSM) for 45 days incubation at 20, 30 and 40 °C. Oxytetracycline glucose yeast extract (OGYE) agar media were prepared over a wide range of a w (0.80–0.95), controlled by glucose. The headspace atmosphere composition varied from 0–20% for O 2 and from 0–80% for CO 2 with N 2 as balance in the ratio medium gas mixture of 1 3 ( v v ). The results of this experiment were confirmed by repeating some combinations ( a w-MAP) in the zone where the inhibition was effective. In contrast to A. niger which germinated and grew better at 30 and 40 °C, P. chrysogenum and F. oxysporum were capable of germinating and growing at 20 °C but not at 40 °C. E. amstelodami was less influenced by the incubation temperature than were the other species. Under anaerobic atmospheres, germination and growth of all tested species were completely inhibited at low a w, while at high a w because of residual O 2, conidia germinated but failed to grow. At any a w value between 0.88 and 0.92, conidia failed to germinate when 100% CO 2 was applied. Similar results were obtained for E. amstelodami and F. oxysporum in 80% CO 2-20% N 2 and 60% CO 2-40% N 2. Under aerobic conditions, at 5% O 2 germination and growth occurred only at high a w, while 10 or 20% O 2 combined with either 80 or 60% CO 2 conidial germination and mould growth were only delayed comparing to the control (air).

Evaluation of media for enumerating heat-stressed, benzoate-resistant Zygosaccharomyces bailii

A study was undertaken to determine the efficacy of yeast malt extract agar (YMA), acidified YMA (YMAA), acidified tryptone glucose yeast extract agar (TGYA) and Zygosaccharomyces bailii agar (ZBA) for enumerating two strains of Z. bailii (FRR 2227 and FRR 3680) grown and heated in blueberry syrup containing 0, 300 and 600 μg ml sodium benzoate. Cells were heated at 50, 51 or 52 °C for 0, 15, 30 or 45 min before spread plating diluted samples on enumeration media and incubating at 30 °C for 5 days. Strain FRR 3680 exhibited higher heat resistance than did strain FRR 2227. Regardless of the sodium benzoate concentration in growth and heating media, or the temperature and time of heating, non-selective YMA supported recovery of the highest number of viable cells, followed by TGYA for strain FRR 2227 and TGYA or ZBA for strain FRR 3680. YMAA supported the lowest recovery of heat-stressed cells. The concentration of sodium benzoate in the growth medium did not have a significant effect on tolerance of strain FRR 3680 to heat; however, tolerance of strain FRR 2227 to heat decreased when cells were grown in blueberry syrup containing increased concentrations of sodium benzoate. Regardless of the sodium benzoate concentration in the growth medium, both strains exhibited increased sensitivity when heated in blueberry syrup containing increased concentrations of sodium benzoate. Overall, TGYA was judged best among selective media for enumerating Z. bailii because of its ability to support colony development by heat-stressed cells and because of the ease of counting and differentiating colonies.

Improved selective medium for enumeration of benzoate-resistant, heat-stressed Zygosaccharomyces bailii

The efficacy of acidified (0.5% acetic acid) tryptone glucose yeast extract agar (TGYA), acidified malt extract agar (MEAA) and Zygosaccharomyces bailiiselective medium (ZBA) to recover seven strains of Z. bailiifrom a mixture of mayonnaise and water (1:1, w:v, mayonnaise:water) heated at 50 and 51°C for up to 45 min was determined. Cells not subjected to heat treatment were recovered in equal numbers on TGYA, ZBA and non-selective yeast malt agar (YMA). Recovery on MEAA was inferior. YMA supported the highest recovery of unheated and heat stressed cells, followed by TGYA and ZBA. Lowest recovery of heated cells was observed on MEAA. The ability of heated Z. bailiicells to recover on acidified (0.5% acetic acid) tryptone fructose yeast extract agar (TFYA), acidified (0.3% acetic acid) tryptone glucose yeast extract agar (TGYAC), acidified (0.5% acetic acid) tryptone yeast extract agar containing sodium benzoate (300 μg ml −1) (TGYACB), acidified (0.3% acetic acid) fructose yeast extract agar (TFYAC) and ZBA containing 0.3% acetic acid (ZBAC) compared with recovery on YMA was investigated. Regardless of the strain, performance of media for recovering heated-stressed cells of Z. bailiiwas YMA=TGYAC=TFYAC>TFYA>TGYA>TGYACB>ZBAC>ZBA. Overall, TGYAC and TFYAC were judged best among selective media for recovering unheated and heat-stressed Z. bailii. However, the ability of these media to inhibit colony formation by several other yeasts, not particularly resistant to acids, is less than adequate. A medium that supports the growth of all healthy and heat-injured cells of Z. bailiibut not other yeast species has yet to be perfected.

Media for preservative resistant yeasts: a collaborative study

An international collaborative study was carried out to determine the most effective medium for selective isolation and enumeration of preservative resistant yeasts. Such a medium should prevent the growth of other yeasts such as Saccharomyces cerevisiae that are tolerant to lower levels of commonly used food preservatives, and sensitive yeasts such as Rhodotomla species. The study compared two non-selective media that are in common use for cultivation of yeasts from foods, Malt Extract agar (MEA) and Tryptone Glucose Yeast extract agar (TGY) with media made selective for preservative resistant yeasts by the addition of 0.5% acetic acid to these two basal media (MEAA and TGYA). A fifth medium, Zygosaccharomyces bailii medium (ZBM) was also included in the study. These media were compared for their efficacy in selective isolation and enumeration of the preservative resistant yeasts Zygosaccharomyces bailii, Schizosaccharomyces pombe and Pichia membranaefaciens. MEA and TGY without acetic acid were used as control, non-selective media, and Rhodotorula glutinis was the preservative sensitive control culture. Seven laboratories in six countries took part in the study. Of the non-selective media, TGY generally gave the highest counts, and TGY amended with 0.5% acetic acid (TGYA) was the best medium for recovery of all three preservative-resistant yeasts. ZBM was found to be selective for Z. bailii, but counts of this yeast on ZBM were significantly lower than on TGYA. R. glutinis did not grow on any of the selective media.

Enumeration of xerophilic yeasts in the presence of xerophilic moulds: a collaborative study

A collaborative study was undertaken to compare the performance of Dichloran 18% Glycerol agar (DG18) with three other media widely used in food mycology, for the enumeration of xerophilic yeasts in the presence of xerophilic moulds. Oxytetracycline Glucose Yeast extract agar, (OGY), Dichloran Rose Bengal Chloramphenicol agar (DRBC) and Malt extract Yeast extract 50% Glucose agar (MY50G) were evaluated. Three reference samples (A, B, C) were prepared using skimmed milk powder inoculated with mixed lyophilized cultures of selected xerophilic yeasts and moulds, at levels around 10 4 to 10 5 CFU/g. Yeast species used were Candida glucosophila, C. versatilis, Zygosaccharomyces ballii and Z. rouxii, together with Eurotium spp. and some other moulds. Collaborators were asked to examine each sample twice, by dilution plating on the four media. Colonies were counted after 3, 5 and 7 days incubation at 25 °C. Fourteen participants from seven laboratories in six countries collaborated in this study. The ability of collaborators to detect and count yeasts after 5 and 7 days on DG18, DRBC and OGY varied depending on the sample. Few participants were able to count yeasts even after 7 days on MY50G. The overall results demonstrated that DG18 incubated 5 days at 25 °C was superior to the other three media tested for the enumeration of xerophilic yeasts in the presence of xerophilic moulds.

Evaluation of diluents and media for enumerating Zygosaccharomyces rouxii in blueberry syrup

Combinations of diluents and enumeration media were evaluated for their efficacy in enumerating Zygosaccharomyces rouxii in blueberry syrup ( a w 0.818, 0.870 and 0.921). Diluents consisted of deionized water containing 0.1% peptone, 20%, 30%, 40% or 50% glucose, 50% glucose plus 0.05% Tween 80, and 12%, 18%, 26% or 35% glycerol, all calculated on a w w basis. Enumeration media were dichloran rose bengal chloramphenicol (DRBC) agar, tryptone glucose yeast extract (TGY) agar, dichloran 18% glycerol (DG18) agar, plate count agar containing 52% sucrose (PCA52S) and malt extract yeast extract 50% glucose (MY50G) agar. Two test strains of Z. rouxii grown in blueberry syrup for 7 or 14 days responded similarly to diluent/enumeration medium combinations. The use of 0.1% peptone diluent or DRBC agar in combination with other enumeration media or diluents was inferior for recovering Z. rouxii. As the a w of the blueberry syrup decreased, the sensitivity of Z. rouxii to diluent containing decreased concentrations of glucose increased. The use of glycerol as a solute in diluent did not result in a similar trend, indicating that the protective effect of glycerol against osmotic stress to Z. rouxii cells is greater than that of glucose at high a w and that cells adapted to low a w in blueberry syrup are more sensitive to high a w in diluents. The addition of 0.05% Tween 80 to 50% glucose diluent did not influence performance. Overall, diluents containing 50% glucose ( a w 0.898), 18% glycerol ( a w 0.956) or 26% glycerol (0.934), in combination with TGY agar ( a w 0.982), resulted in the highest recovery of Z. rouxii from blueberry syrup at a w 0.818 to 0.921.

Significance of Insensitivity ofSclerotinia minorto Iprodione in Control of Sclerotinia Blight of Peanut.

Four hundred isolates of Sclerotinia minor were obtained from diseased peanut plants (Arachis hypogaea) in field plots untreated or treated three times with iprodione (1.12 kg/ha) in 1987. On glucose-yeast extract agar containing iprodione at 2 μg/ml, only 6% of the isolates grew. These isolates produced more mycelial growth than corresponding isolates not previously exposed to the fungicide in agar, indicating that insensitivity developed in vitro. In field microplots artificially infested with sclerotia of the insensitive isolates and planted to peanut for 7 yr, iprodione provided significant disease suppression even though insensitive isolates could still be recovered. In a separate 3-yr microplot study, the pathogenicity of an isolate (B-83-T2) of S. minor suspected of possessing field resistance to dicarboximide fungicides was compared to a sensitive isolate (S-2) after treatment of peanuts with dicarboximide fungicides (iprodione or vinclozolin), aromatic hydrocarbon fungicides (dicloran or pentachloronitrobenzene [PCNB]), and an experimental fungicide (fluazinam). Without fungicide treatment, disease incidence (stem lesions per microplot) at harvest averaged 19.9 in plots infested with isolate S-2 and 18.3 in plots infested with isolate B-83-T2 (no statistical difference), but yields were significantly lower (10%) in microplots infested with isolate S-2. When averaged across isolates, disease incidence was suppressed 96, 63, 42, 41, and 2O% by fluazinam, vinclozolin, iprodione, PCNB, and dicloran, respectively. Insensitivity in S. minor to the dicarboximide fungicides appears low but persistent and does not pose a threat to the continued use of dicarboximides or related fungicides in peanut production

Temperature Requirements of Selected Marine Fungi

The growth responses of nineteen marine fungi to temperature (10, 20, 30°) and selected media were studied. Poor growth was recorded at 10°C on all media. Growth was greatest at 20°C and 30°C on all media, with the exception of Amylocarpus encephaloides and Marinospora calyptrata with no growth at 30°C. for growth was 20°C for nine fungi (eleven strains) [Ceriosporopsis halima, Marinospora calyptrata encephaloides, Lulworthia sp., Asteromyces cruciatus, Dendryphiella arenaria, Monodictys pelagica (2 strains), Nia vibrissa (2 strains), Digitatispora marina] and 30°C for seven fungi (eight strains) [Corollospora maritima (2 strains), Halosphaeriopsis mediosetigera, Zalerion maritimum, Periconia prolifica, Hydronectria tethys, Hypoxylon oceanicum, Nais glitra]. Slight difference in growth was recorded on the four media employed with increased growth on sea water corn meal agar and sea water starch yeast extract glucose agar