Exophiala pisciphila

Exophiala pisciphila is a dematiaceous fungus that belongs to a group of fungi known as the black yeasts. It was isolated from the skin lesions of a smooth dogfish, Mustelus canis Mitchill, that had been born in the shark exhibit tank of the New York Aquarium. The different stages of development of this fungus were studied by light microscopy and scanning electron microscopy to illustrate the morphology and surface structures of conidia and mycelium. The list of marine and fresh water fish, which have been infected by Exophiala spp. and Exophiala-like fungi has been up-dated. Potato Dextrose Agar and Malt Agar proved to be the best growth media, while Corn Meal Agar proved to be the best medium for studying the morphological features of the conidia and mycelial development of E. pisciphila, which exhibited polymorphic conidiogenesis.     

Fusarium pallidoroseum L. on castor (Ricinus communis) in Samaru,Nigeria

Diseased castor leaves were collected from the Institute for Agricultural Research (IAR) fields and taken to the laboratory for isolation. Leaves were grown on Potato Dextrose Agar with Streptomycin and incubated for seven days. Grown cultures were observed under microscope and Fusarium pallidoroseum was isolated as confirmed by IMI. Inoculated leaves showed symptoms of wilts and blight.     

Cultural,morphological and bio-chemical variability of different isolates of Colletotrichum truncatum causing anthracnose of greengram

A laboratory experiment was conducted to study the variability among the eight isolates of Colletotrichum truncatum of greengram collected from different locations on the basis of cultural, morphological and biochemical characteristics by using nine different culture media viz., Potato Dextrose Agar (PDA), Potato Carrot Agar (PCA), Oat Meal Agar (OMA), Corn Meal Agar (CMA), Carrot Agar (CA), Sabouraud’s Agar (SA), Czapek’s Dox Agar (CDA), Richard’s Agar (RA) and V₈ Juice Agar. Colony colour varied in different media from white or white with light brown centres which later changed to black or dark to light brown with increase in the age of the fungal cultures. Mostly, the colonies had fluffy or cottony mycelial growth with slight variations and regular to irregular white margin. PDA, PCA, CA and RA produced maximum mycelial growth (90?mm) at 10 DAI (days after inoculation). Minimum growth was observed on SA (69.56?mm) and V₈ juice agar media (55.42?mm) and their difference was statistically significant. Morphological variability among the isolates was studied by comparing their conidial length, breadth and length and breadth of setae and their differences were statistically significant. Biochemical variability among the isolates was based on α- and β-esterase and peroxidise profiling. Positive activity was observed for both α- and β-esterase. α-Esterase enzyme showed the highest enzyme activity in terms of maximum numbers of banding loci among the three isozymes tested. The findings of the present study clearly revealed that cultural, morphological and biochemical variability did exist among the different isolates of C. truncatum.     

Segregation pattern of gene expression in cotton leaf curl virus-resistant transgenics

Non-pathogenic soil bacteria living in association with roots of higher plants enhance their adaptive potential and thus could be beneficial for their growth. Here, we present the current status of the use of Bacillus subtilis in biocontrol. Rhizobacteria are found in the rhizosphere. Plant growth promoting rhizobacteria (PGPR) strains, such as Bacillus and Pseudomonas, were isolated by using Nutreint dextrose Agar medium or Potato Dextrose Agar medium. The selection of PGPR strains was done by duel culture methods against the potato pathogens. The interaction of PGPR (Bacillus) with potato seeds or vegetative parts show promising antagonism by virtue of producing siderophore and antibiotics against black scurf and stem canker diseases of potato caused by Rhizoctonia solani, thereby resulting in increase of potato yield. The effectiveness of PGPR strain (Bacillus spp.) in improving the yield of potato in greenhouse conditions and in the field was observed.     

First report of oral colonization by <Emphasis Type="Italic">Debaryomyces nepalensis</Emphasis> in a dog

A stray, young male, wire-haired pointing griffon dog, found in a street of Perugia (Italy), was examined in order to check his health status. Two oropharyngeal swabs were collected in 24 h and streaked onto Sabouraud agar and after 6 days the yeasts colonies were transferred onto Malt agar. Ascospores were observed on Potato Dextrose Agar medium. The major ubiquinone of an isolated yeast was identified as ubiquinone-9 (Q-9), and genetical analyses were performed together with the type strains of Debaryomyces hansenii (var. hansenii and var. fabry), C. psychrophila and D. nepalensis type strain. The base sequences of ITS1 and ITS2, and D1/D2 domains of LSU rDNA completely coincided with those of D. nepalensis. From these results, the isolated yeast was identified as D. nepalensis. RAPD patterns between the two strains were found to be identical. The results indicate the first colonization of D. nepalensis in a dog.     

Identification and host range of causal agent of dieback disease on Jatropha curcas

Diseased Jatropha branches collected from Institute for Agricultural Research (IAR), Samaru, Zaria field were plated in Potato Dextrose Agar with Streptomycin (PDAS) and incubated for seven days. Grown cultures were observed under microscope and with aid of identification manuals Fusarium sp. was isolated. Inoculated seedlings showed symptoms of dieback. The fungus was also inoculated on some crop plants and it induced the typical dieback symptoms on sesame and leaf spot/ blight on groundnut and soya beans, respectively.     

Inactivation of Salmonella serovars by Pseudomonas chlororaphis and Pseudomonas fluorescens strains on tomatoes

Salmonella enterica and its serovars have been associated with pathogen contamination of tomatoes with numerous outbreaks of salmonellosis. To improve food safety, pathogen control is of immediate concern. The aim of this research was to assess the populations of natural microflora (aerobic mesophilic bacteria, lactic acid bacteria, yeasts and moulds and Pseudomonas species) on tomatoes, and evaluate the efficacy of Pseudomonas fluorescens (Pf) and Pseudomonas chlororaphis (Pc) for inactivation of Salmonella on tomatoes. Microflora were determined on sanitised and unsanitised produce and enumerated on Plate Count Agar, de Man, Rogosa and Sharpe medium, Potato Dextrose Agar and Pseudomonas Agar F media. The efficacy of Pc and Pf for inactivation of S. enterica serovars Montevideo, Typhimurium and Poona was determined on spot-inoculated tomato stem scars. The effects of storage time on bacterial populations were also investigated. On unsanitised tomatoes, lactic acid bacteria, Pseudomonas sp., aerobic mesophilic bacteria and yeasts and moulds ranged from 3.31–4.84, 3.93–4.77, 4.09–4.80 and 3.83–4.67 log CFU/g of produce, respectively. The microflora were similar at 0 and 24 storage hours on sanitised produce. The suppression of Salmonella Montevideo by P. chlororaphis and P. fluorescens on tomatoes ranged from 0.51 to 2.00 log CFU/g of produce. On Salmonella Montevideo and S. Typhimurium, the suppressive effects ranged from 0.51 to 0.95 and 0.46 to 2.00 log CFU/g of produce, respectively. The pathogen suppressive effects may be attributed to competition ability of Pseudomonas relative to Salmonella strains. Pseudomonas strains may be effective against Salmonella strains as a post-harvest application, but strain synergy is required to optimise pathogen reductions.     

Phosphate directed Y-M variation in candida albicans

Summary The influence of pH, O-R potential, dextrose/inorganic phosphate ratio, nitrogen source, and various cations on filamentation ofCandida albicans when grown on phosphate enriched Sabouraud Dextrose Agar (Difco) at 37° C were investigated. The dextrose/phosphate ratio apparently plays a key role under these conditions. It is postulated that magnesium ion trapped within the cell by excess polyphosphate formation leads to filamentation.Supported by U.S.P.H.S. E-1700 and U.N.C. Research Council 324-ALU-1 (360).     

红色毛癣菌临床分离株的菌落形态和镜下结构特征再分析

目的探讨红色毛癣菌的菌落形态和镜下结构特征以及与感染部位的相关性。方法采用传统培养方法对192株红色毛癣菌进行表型分型,选取其中39株在28℃、30℃、35℃3种温度孵育6d、10d、14d时观察菌落形态和生长速度。结果192株红色毛癣菌共分离出3种表型：绒毛型、沟纹型、粉末型（或颗粒型）。在相同培养基上,28℃、30℃时菌落生长速度无显著差异（P〈0.05）,均快于35℃（P〈0.05）。在相同温度时,菌落在SDA上的生长速度快于PDA培养基。在28℃、30℃时菌落形态比较稳定,在35℃时变异较大。菌落在PDA培养基上产孢丰富,镜下显示有较多的大、小分生孢子,而在SDA培养基上只有少量的小分生孢子,几乎见不到大分生孢子。各种浅部感染均以绒毛型为主,绒毛型在手足癣中占比例最高,沟纹型在体股癣中所占比例较高,粉末型在甲癣中占的比例较高。结论红色毛癣菌的菌落形态与培养基和培养温度有关,其表型和镜下结构与感染部位均有一定的相关性。     

Enumeration of byssochlamys and other heat-resistant molds

Methods for the detection of low numbers of heat-resistant molds on fruits were studied by using cultures of Byssochlamys and a number of unidentified mold isolates. Ascospore dormancy had a marked effect on viable recoveries, and the medium in which ascospores were heated influenced activation rates. Best results were obtained when fruit homogenates were heated for 60 min at 70 C in Concord grape juice, followed by culturing on acidified Potato Dextrose Agar.     

Morphological and molecular identification of Leptosphaeria maculans in canola seeds and flowers collected from the North Iran

Blackleg disease, caused by Leptosphaeria maculans, is one of the most important diseases of rapeseed Brassica napus in Iran as in other regions of the world. The samples including canola petals and seeds were collected during 2014–2015 from canola field in North Iran. Isolates characteristics of fungus were assessed based on the colony growth rate and pycnidia in Potato Dextrose Agar. The pycnidia of the fungus were black, globose to subglobose in shape, the single-celled conidia, hyaline and fusiform with diameters of 4–5 × 1.5–2 μm. Most of the isolates were produced pigment in the liquid culture in variable color brown to black. Thirteen isolates were then separated into pathogenicity groups based on the interactions on B. napus differential cultivars. For the direct detection of seed contamination with L. maculans, PCR was developed using specific primers pair (LmacF, LmacR) which can amplify ITS1 and ITS2 along with the 5.8S rRNA region of L. maculans genome. Based on the followed information and sequence analysis, the fungal isolates from these samples were identified as L. maculans. The findings of this research showed that the disease was aggressive and highly distributed from infested seeds to oilseed rape fields.     

Antibacterial activity of the leaf essential oil of <Emphasis Type="Italic">Blumea mollis</Emphasis> (D. Don) Merr.

The antibacterial activity of the leaf essential oil of Blumea mollis was assayed against 14 clinically isolated bacterial strains on Muller–Hinton Agar medium and Muller–Hinton Agar medium with 5% sheep blood. The essential oil had promising antibacterial activity against all the bacterial strains tested. The highest mean zone of inhibition and lowest values of minimum inhibitory concentration were recorded against methicillin-resistant Staphylococcus aureus followed by beta hemolytic Streptococcus pyogenes. The Gram-positive bacteria were more sensitive than Gram-negative bacteria. Among the bacterial strains tested, Psudomonas aeruginosa was resistant to the essential oil. The results of the present study suggest that the essential oil of B. mollis is one of the new medicinal resources as an antibacterial agent against the bacterial strains tested.     

Antifungal activity of plants extracts against Alternaria solani,the causal agent of early blight of tomato

Aqueous extracts of 39 plants selected from local flora were evaluated for antifungal potential against Alternaria solani, causing early blight of tomato, at 4% concentration in Potato Dextrose Agar by poison food technique. Out of these, 13 plant extracts significantly reduced the mycelial growth of the pathogen, according to ANOVA, Tukey’s post-test. Inhibition rate of above 20% was shown by seven plant extracts namely Crotalaria trichotoma (36.6%), Citrus aurantifolia (27.3%), Azadirachta indica (23.7%), Polyalthia longifolia (23.3%), Datura metel (21.3%), Muntingia calabura (20.09%) and Oxalis latifolia (20.09%). At 2% concentration, six extracts showed significant growth inhibition namely, C. trichotoma (16.6%), A. indica (10%), Capsicum annum (7.1%), D. metel (6.6%), P. longifolia (6.3%) and C. aurantifolia (5.5%). The plant extracts shortlisted for pathogen inhibition have potential to be developed as potent fungicides in organic farming.     

The growth of Epidermophyton floccosum and E. stockdaleae at different temperatures

The ability of 17 strains of genus Epidermophyton (15 strains belonging to Epidermophyton floccosum, one to E. floccosum var. nigricans and one to E. stockdaleae) to grow at different temperatures (4 °C, 25 °C, 28 °C, 31 °C, 34 °C, 37 °C and 40 °C) was stated.The strains were inoculated on Sabouraud Dextrose Agar and regularly controled over a period of 14 days when the plates were incubated at 25 °C, 28 °C, 31 °C, 34 °C, 37 °C and 40 °C, and over a period of 70 days when the temperature was 4 °C. The optimal growth of E. floccosum was observed at 28 °C and 31 °C, and no signs of growth were recorded neither at 4 °C nor at 40 °C. The optimal development of E. stockdaleae was observed at 25 °C and 28 °C. This species grew from 4 °C to 31 °C.     

Characterization of Pythium spp. associated with root rot of tobacco seedlings produced using the float tray system in Zimbabwe

The study was undertaken to identify and characterize Pythium isolates associated with root rot disease of tobacco seedlings as a first step towards developing management strategies for the pathogen. A total of 85 Pythium isolates were collected from diseased tobacco seedlings during 2015–2016 tobacco growing season. The isolates were identified to species level using sequencing of the internal transcribed spacer region. Thereafter, a subset of the isolates was tested for sensitivity to the commonly used fungicides, metalaxyl, azoxystrobin and a combination of fenamidone/propamocarbby growing isolates on Potato Dextrose Agar plates amended with the fungicides. The sequence analysis of the ITS‐rDNA identified Pythium myriotylum as the dominant Pythium species associated with the root rot of tobacco seedlings in Zimbabwe. Pythium aphanidermatum and P. insidiosum were also identified albeit at lower frequencies. Phylogenetic analyses of the ITS region of the P. myriotylum isolates showed little sequence diversity giving rise to one distinct clade. The fungicide sensitivity tests showed that metalaxyl provided the best control of P. myriotylum in vitro, as compared to other fungicides. To the best of our knowledge, this is the first comprehensive study to determine and characterize Pythium species associated with root rot of tobacco in the float seedling production system in Zimbabwe.     

Aspergillus penicillioides—a true halophile existing in hypersaline and polyhaline econiches

Aspergillus penicillioides is a true halophile, present in diverse econiches from the hypersaline athalassohaline Dead Sea and the thalassohaline solar salterns, to the polyhaline estuaries and mangroves of Goa-India. Thirty-nine isolates from these environments were seen to be moderate halophiles, stenohaline or euryhaline in nature, with comparable salt tolerance indices. They had an obligate need for a low water activity and were unable to grow on a regular defined medium such as Czapek Dox Agar, or on various nutrient rich agar media such as Malt Extract, Potato Dextrose and Sabouraud Agar; however, growth was obtained on all these media when amended with 10 % solar salt. In the absence of added salt, the conidia either did not germinate, or when germinated, distortions and lysis were seen in the short mycelial forms; on media with salt, the mycelia and vesicles appeared normal.     

三种白腐菌生物学特性与木质纤维素酶基因遗传多样性

以采自东北林业大学帽儿山实验林场的3种白腐真菌——木蹄层孔菌(Fomes fomentarius)、鲍姆鲍姆木层孔菌(Phellinus baumiibaumii)和火木层孔菌(Phellinus igniarius)为材料,用菌落直径测量法比较3种白腐菌在马铃署葡萄糖固体培养基上的生长速度,采用菌丝体干重法比较其在马铃署葡萄糖液体培养基中的生物量变化。结果显示:马铃薯葡萄糖固体培养基上3种白腐菌均为快速生长类型,其生长速度木蹄层孔菌火木层孔菌鲍姆鲍姆木层孔菌;马铃署葡萄糖液体培养基中生物量增长速度木蹄层孔菌鲍姆鲍姆木层孔菌火木层孔菌。用比色法测量其木质纤维素酶活性,结果显示:木蹄层孔菌产锰过氧化物酶和漆酶量较高,鲍姆鲍姆木层孔菌和火木层孔菌产木质素过氧化物酶量较高;木蹄层孔菌、鲍姆鲍姆木层孔菌和火木层孔菌3种白腐菌的3种主要木质素酶(锰过氧化物酶、漆酶和木质素过氧化物酶)的表达量,种间差异显著(F=3.75*、5.20**、3.01*),白桦木屑诱导处理与对照间差异显著(F=3.84*、4.19*、5.28*);两种主要纤维素酶(葡聚糖内切酶、葡聚糖外切酶)的表达量,种间差异不显著,受碳源影响作用显著(F=3.99*、4.04*)。筛选29对引物组合,对3种白腐菌几种主要木质纤维素酶基因进行TRAP-PCR分子标记检测,比较3菌种间遗传差异,扩增总条带数为357条,多态性条带数为255条,多态性条带的比例为71.43%,其中木质素降解酶基因总多态位点比率为73.77%,纤维素降解酶基因总多态位点比率为68.97%。3种白腐菌的木质纤维素降解酶基因在种间均存在较高的遗传差异。因此,特定基因的TRAP分子标记可以用于木腐菌的遗传变异分析。     

Effect of the Conditions of Incubation in the Recovery of Oral Actinomyces

The Gram-positive Pleomorphic Bacilli (GPPB), especially the genus Actinomyces, are part of the oral microflora and they are generally associated with cement caries. They are also found in inactive sites in periodontal disease and in pulpar infections. The aim of the present work was to find an appropriate isolation culture medium for the recovery of the genus Actinomyces from oral samples, and to propose a minimum schema of biochemical tests for the identification and differentiation of Actinomyces species from other GPPB. Samples of saliva, subgingival plaque and post-extraction acute alveolar osteitis were cultivated in Starch Casein Agar (SCA), Yeast Extract Dextrose Agar (YDA), Columbia Blood Agar 5% (BA), both with cephadroxyl (10 μL/mL) and without antibiotic. The plates were incubated in aerobic conditions, in strict anaerobic conditions and in a candle jar for 5 days at 37°C. (1) The highest recovery of Actinomyces was obtained in BA without antibiotic in a candle jar for all oral samples. (2) In all the incubated in SCA, YDA and BA with antibiotic,Actinomyces , other GPPB, Gram-positive and -negative cocci and Gram-negative bacilli showed growth in all aerobic conditions. (3) In BA medium with antibiotic the Gram-negative microflora was inhibited, the Actinomyces recovery being lower than in the other media studied.     

Application of Replica Plating and Computer Analysis for Rapid Identification of Bacteria in Some Foods: I. Identification Scheme

A method was devised and tested for a quantitative identification of microbial flora in foods. The colonies developing on the initial isolation plates were picked with sterile toothpicks and inoculated on a master plate in prearranged spacing and order. The growth on the master plates was then replicated on a series of solid-agar plates containing differential or selective agents. The characteristic growth and physiological responses of microbial isolates to penicillin, tylosin, vancomycin, streptomycin, chloramphenicol, neomycin, colistin, and to S S Agar, Staphylococcus Medium No. 110, and Potato Dextrose Agar were recorded, together with Gram reaction and cell morphology. This information was then fed into an IBM 1410 digital computer which grouped and analyzed each isolate into 10 microbial genera, or groups, according to the identification key. The identification scheme was established by use of reference culture studies and from the literature. This system was used to analyze the microbial flora in dover sole (Microstomus pacificus) and ground beef. The method described in this article enables one to examine large numbers of microbial isolates with simplicity.     

Saccharomycomorpha psychra n. g., n. sp., a Novel Member of Glissmonadida (Cercozoa) Isolated from Arctic and Antarctica

A novel genus and species within the order Glissmonadida (Cercozoa, Rhizaria), Saccharomycomorpha psychra n. g., n. sp., is described from lichen in the Ny-Ålesund region (High Arctic) and moss in the Fildes peninsula of King George Island (Maritime Antarctica). Cells were spherical and did not appear to present flagella in organic-rich Potato Dextrose Agar medium where they were able to feed osmotrophically. Molecular phylogenetic analyses based on 18S rRNA gene sequence demonstrated that Saccharomycomorpha psychra belong to “clade T” within the order Glissmonadida (Cercozoa, Rhizaria). All three investigated strains could grow at 4 °C and had an optimum growth temperature of 12 °C, 20 °C, and 20 °C, while a maximum growth temperature of 20 °C, 20 °C, and 25 °C, respectively. In conclusion, we established the phenotypic identity of “clade T,” which until now was exclusively detected by environmental sequences, and erect a new family Saccharomycomorphidae for “clade T.” Nomenclatural, morphological and ecological aspects of this novel species are discussed.