Yeast Malt Agar Research Articles

In vitro Antioxidant activity of extracellular L-glutaminase enzyme isolated from marine yeast Rhodotorula sp. DAMB1

Yeasts from marine ecosystem have been recognized as producers of several bioactive compounds and also for various enzyme productions. The present study mainly focuses on the extracellular production, medium optimization and in vitro antioxidant activity of L-glutaminase enzyme from marine yeasts isolated from marine water samples of the backwaters of Andaman-Nicobar islands, India. A total of 26 marine yeast isolates were recovered using yeast malt agar (YMA) medium. After primary screening using minimal glutamine agar, 4 marine yeast isolates DAMB1, DAMB2, DAMB3 and DAMB4 showed positive enzyme activity. Zones of hydrolysis for DAMB1 and DAMB3 were 40mm and 30mm respectively. Further, secondary screening was done for the two potential yeast isolates at pH 7.6 along with nesslerization for quantitative analysis. Yeast isolate DAMB1 showed highest L-glutaminase enzyme activity of 67%. This was followed by medium optimization for better production of L-glutaminase enzyme. The optimum temperature and pH was 37°C and pH 8 respectively. Optimum carbon source was arabinose and optimum nitrogen source was found to be casein. The potential yeast isolates showed good antioxidant activity too. DAMB1 showed highest DPPH activity of 62% and DAMB2 showed DPPH activity of 47%. The potential yeast isolate was identified as Rhodotorula sp. DAMB1 (Acc. No. MK968443) using 18s rRNA sequencing method.

Short Communication: Isolation and characterization of thermophilic actinobacteria as proteolytic enzyme producer from Ie Seuum Hot Spring, Aceh Besar, Indonesia

Abstract. Fitri L, Putri KA, Suhartono, Ismail YS. 2019. Short Communication: Isolation and characterization of thermophilic actinobacteria as proteolytic enzyme producer from Ie Seuum Hot Spring, Aceh Besar, Indonesia. Biodiversitas 20: 2802-2808. Proteases are enzymes who catalyze the breakdown of peptide bonds in proteins. This enzyme could be produced from thermophilic bacteria that are able to grow at temperatures of 45-80ºC and are stable to heat. The samples were collected at Ie Seu'um hot spring, Aceh Besar. This study aimed to isolate, to characterize and to determine actinobacteria that were capable of producing protease enzymes. The sampling method in this study was conducted by purposive sampling at temperatures of 50, 60 and 70ºC. Isolation of thermophilic actinobacteria was carried out in Humic Acid Vitamin B (HV) Agar medium and morphological characterization was carried out in Yeast Malt Agar (YMA), Yeast Starch Agar (YSA), Oatmeal Agar (OA) media. Microscopic characterization and measurement of clear zone diameter formed were carried out in skim milk medium. The results showed that one actinobacteria isolate was obtained at a temperature of 50ºC and five isolates at a temperature of 60ºC, meanwhile, no actinobacteria could be obtained at a temperature of 70ºC. A total of 4 isolates obtained were able to produce protease enzymes. The highest Proteolytic Index (IP) value was obtained from IS01 which was 3.8.

Mycelial Growth Characteristics of Pleurotus citrinopileatus and Pleurotus platypus in Culture Media Variants

Pleurotus species, because of their flexible temperature and environmental requirements, have more cultivated species than any other mushrooms. As one of the preliminary experiments for standardizing the cultivation technique of Pleurotus citrinopileatus and Pleurotus platypus, this work was done to find out the basic nutrient requirements and hence the effect of seven different growth media namely Potato dextrose agar (PDA), Malt extract agar (MEA), Yeast malt agar (YMA), Sabouraud's dextrose agar (SDA), Czapek dox agar (CDA), Glucose peptone agar (GPA) and Oat meal agar (OMA) on the mycelial growth of these mushrooms at room temperature(28°C) for a period of 8 days. Since the mycelium of Pleurotus platypus showed a non-symmetrical spreading pattern, the average growth was measured drawing cross sections on the petriplate. The experiments were done in six replications and colony diameter (CD), mycelial density (MD), growth rate (GR) of the mycelium were recorded. The CD of both Pleurotus citrinopileatus and Pleurotus platypus showed outstanding results in PDA medium with a GR of 1.13cm/day and 0.75cm/day respectively. The highest MD for Pleurotus citrinopileatus was indicated in PDA and MEA and for Pleurotus platypus it was in PDA, MEA and YMA. Though mycelial density did not follow the same pattern of inference as colony diameter, there was a positive correlation between CD and MD in all the experimental plates. The overall study proved PDA followed by MEA to be the most suitable media for culturing both Pleurotus citrinopileatus and Pleurotus platypus under in vitro conditions.

Detection of antibiotic-producing Actinobacteria in the sediment and water of Ma'in thermal springs (Jordan).

Detection of new Actinobacteria is significant to discover new antibiotics because development of new antibiotics is connected to the characterization of novel bacterial taxa. This study has focused on the identification and isolation of antibiotic-producing Actinobacteria from the sediment and the water of Ma'in thermal springs (48-59°C) situated in the center area of Jordan. Samples of sediment and water were transferred to glucose yeast malt agar medium and Actinobacteria were cultivated, isolated and identified according to scanning electron microscopy and 16S rRNA gene analysis. Antibacterial activities of the isolates were then tested against different test bacteria by agar well diffusion method. Three different species of Actinobacteria were isolated (M1-1, M2-2, M3-2) from sediment samples. Based on 16S rRNA gene analysis, isolate M1-1 was found to have only 90% identity percentage with Nocardiopsis sp., however, isolates M2-2 and M3-2 were found to be closely related Streptomyces sp. (97%) and Nocardioides luteus (99%), respectively. The antibacterial activity showed that strain M1-1 is active against P. aeruginosa ATCC 2785 (inhibition zone, 9 mm). Strain M2-2 was found to be active against S. aureus ATCC 29213 (12 mm), B. cereus ATCC 11778 (11 mm), and E. coli ATCC 25922 (9 mm). In respect to strain M3-2, it was found to be active against S. aureus ATCC 29213 (14 mm) and B. cereus ATCC 11778 (9 mm). There were no actinobacterial isolates obtained from water samples despite their significant diversity revealed by our previous metagenomic analysis, which showed the presence of 13 different species dominated by Arthrobacter (an Actinobacterium belonging to family Actinomycetales). There were 17 different Actinobacteria that could be detected in Ma'in thermal springs (13 unculturable species and 3 culturable species). The culturable Actinobacteria were found to have some antimicrobial activity. Further chemical analysis of the bioactive compounds is recommended.

Caves as a source of new antimicrobial agents: the case study of antibacterial activity from microorganisms inhabiting Cerâmica Cave, Portugal

Antibiotics have been developed for more than 80 years but presently there is an evident decline on their effectiveness due to the development of resistance by pathogens. The arising of multi drug resistant pathogens, has become a serious threat to public health. Microorganisms play a central role in nature as well as in drug discovery with a long track record as important sources of bioactive natural products revealing a wide array of molecules. Although many approaches have been applied to solve this crisis, in the last decades the focus on extreme habitats as gain attention due to peculiar features and due to the presence of unique microbial populations inhabiting these ecosystems. Caves are considered extreme environments, usually oligotrophic, being in general devoid of light, and presenting stable conditions (temperature, humidity) throughout the year. We present the first analysis of antimicrobial activity of bacteria isolated from Cerâmica Cave, located in the Sicó karst massif, central Portugal. Microorganism acquisition was performed through a variety of physical and chemical treatments: dry-heat, wet-heat, dry-heat plus phenol (1,5%), phenol (1,5%), microwave irradiation, rehydration centrifugation, and no-treatment, along with three media: R2A agar, Actinomycetes isolation agar and Yeast-malt agar. A primary antimicrobial activity screening, through cross streak method, was performed in 28 isolates, using two different incubation periods and different target agents (Staphylococcus aureus, Bacillus cereus, Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, Aeromonas salmonicida, Salmonella typhimurium and Enterococcus faecalis). A total of 7 isolates presented antagonistic activity against B. cereus, P. aeruginosa, E. coli, A. salmonicida S. typhimurium and S. aureus. This study proves the ability of cave microorganisms to inhibit both Gram positive and Gram negative pathogenic strains, highlighting the potential of caves microbiome to be one of the answers to solve the current global crisis of multi drug resistant pathogens.

Screening of antibiotic-producing Streptomyces from marine sediments of Bangladesh

Antimicrobial resistance is a rising concern in the treatment of infectious diseases and the discovery of potential antimicrobial compounds is needed to combat against it. The focus of this study was the in vitro antimicrobial activities of Streptomyces obtained from the soil samples collected from different places of Cox’s Bazar, Bangladesh. A total of 156 isolates was obtained from thirty soil samples using two selective media namely yeast malt agar and starch casein agar. The isolates were morphologically distinct on the basis of spore mass color, reverse slide color, aerial and substrate mycelia formation and production of diffusible pigment. Among the isolates, 12 exhibited good antimicrobial activity against the tested micro-organisms. Isolates were subjected to biochemical characterization and identified as Streptomyces spp. The results suggest that the Streptomyces species could be a promising source for potential antibacterial agents.

GREEN SYNTHESIS AND CHARACTERIZATION OF MARINE YEAST-MEDIATED SILVER AND ZINC OXIDE NANOPARTICLES AND ASSESSMENT OF THEIR ANTIOXIDANT ACTIVITY

Objective: The present study focuses on the synthesis of silver and zinc oxide (ZnO) nanoparticles from marine yeasts, isolated from the sediments of the Bay of Bengal, Bakkhali coast, West Bengal, and India.Methods: The marine sediment samples were diluted through serial diution and cultured onto yeast malt agar medium by the spread plate method. The selected yeast isolates were screened for the biosynthesis of silver and ZnO nanoparticles. Characterization of both the nanoparticles was done by applying ultraviolet (UV)-visible spectroscopy, atomic force microscopy, scanning electron microscopy, and Fourier transform infrared spectroscopy.Results: A total of five marine yeasts isolates were able to synthesize silver and ZnO nanoparticles as evidence of the color change. Optical density was measured in UV-spectrometer at different time interval for the conformation of production of nanoparticles. The size of silver nanoparticle was 31.78 nm and ZnO nanoparticle was 86.27 nm. The synthesized nanoparticles are then used for antioxidant assays.Conclusions: We are concluding that marine yeast isolates SAG1 and SAG2 both are potential marine yeast isolates which can synthesize both the silver and ZnO nanoparticles. They also showed good antioxidant activity.

English

The actinobacteria are the most abundant bacterial group in the soil, where they present different characteristics and antagonistic effects on other microorganisms. The objectives of this study were to characterize and evaluate the antagonistic effect of actinobacteria from the semiarid region on rhizobia from the same climatic region. Tests were performed to observe chromogenic and micro-morphological characteristics, tolerance to pH levels of melanin production, and use of carbon sources. This occurred due to the use of modified CDA culture media and basal medium supplemented with specific carbon sources, as well as the use of Ral color chat to observe the colonies. The in vitro antagonism on rhizobia was evaluated in yeast malt agar (YMA) culture medium for the observation of inhibition halo by actinobacteria. We observed different characteristics in relation to the color of aerial mycelium and reverse pigments; tolerance to media with acid and alkaline pH; and production of melanoid pigment occurred only in three strains. The morphological characteristics were described for genera Streptomyces and Saccharothrix, later confirmed by molecular sequencing. These genera were generalists in use of carbon sources, showing their physiological versatility. Regarding antagonism, nine strains of the genus Streptomyces were able to inhibit in vitro strains of Rhizobium tropici and Bradyrhizobium yuanmingense also coming from semiarid soils. The antagonism between actinobacteria and rhizobia can directly affect the symbiosis between nitrogen-fixing bacteria and leguminous plants. These results are pioneering in observing antagonism of these species of rhizobia under the climate condition of the semiarid region, and may contribute to agricultural biotechnology. Key words: Streptomyces, soil, microbe interactions, Brazil, agricultural biotechnology, actinobacteria, antagonistic effect.

Antifungal and antioxidant activities of Coleonema album and C. pulchellum against skin diseases

Context: Coleonema album (Thunb) Bart. & H. L. Wendl (Rutaceae) has been used in the formulation of skincare products, and the Khoisan people rub it on their skin to add luster. Coleonema pulchellum I. Williams has received less attention in the South African traditional medicine. Objective: This study investigates the antifungal and antioxidant activities of C. album and C. pulchellum essential oil (EO) and leaf extracts; and analyzes the chemical components of their EOs. Materials and methods: Antifungal activity of leaf extracts was determined using the microdilution method with griseofulvin and ketoconazole as controls. Antifungal capacity of EO was investigated using the ‘Volatile release plate method’. Trichophyton rubrum (ATCC 28188) and T. mentagrophytes (ATCC 9533) mycelia (0.3 cm diameter) were placed on fresh yeast malt agar in Petri dishes with filter paper (impregnated with 20 μL of EO) on the lid for direct exposure to EO volatiles while plates without EO were used as controls. The incubation time was seven days. Antioxidant activities of the leaf extracts were determined. Results: Methanol leaf extract of C. pulchellum inhibited the growth of three fungi tested with MIC values of 195, 391 and 49 μg/mL for Trichophyton rubrum, Trichophyton mentagrophytes and Microsporum gypseum, respectively. Terpenes formed the major components of the EO. The EO from both plants inhibited the growth of T. rubrum in vitro. Discussion and conclusion: This study revealed the therapeutic value of C. pulchellum. Coleonema album and C. pulchellum should be considered as potential plants for skin ointment from natural origin.

Distribution of tannin-'tolerant yeasts isolated from Miang, a traditional fermented tea leaf (Camellia sinensis var. assamica) in northern Thailand

Miang is a fermented food product prepared from the tea leaves of Camellia sinensis var. assamica, and is traditionally produced in mountainous areas of northern Thailand. Although Miang has a long history and reveals deep-rooted cultural involvement with local people in northern Thailand, little is known regarding its microbial diversity. Yeasts were isolated from 47 Miang samples collected from 28 sampling sites, including eight provinces in upper northern Thailand. A hundred and seven yeast isolates were recovered and identified within 14 species based on the comparison of the D1/D2 sequence of the large subunit (LSU) rRNA gene. Candida ethanolica was determined to be the dominant species that was frequently found in Miang together with minor resident yeast species. All yeast isolates demonstrated their tannin-tolerant capability when cultivated on yeast malt agar (YMA) containing 50g/l tannin, but nine isolates displayed clear zones forming around their colonies, e.g., Debaryomyces hansenii, Cyberlindnera rhodanensis, and Sporidiobolus ruineniae. The results obtained from a visual reading method of tannase revealed that all yeast isolates were positive for methyl gallate, indicating that they possess tannase activity. It is assumed that a tannin-tolerant ability is one of the most important factors for developing a yeast community in Miang. This research study is the first report to describe tannin-tolerant yeasts and yeast communities in traditionally fermented tea leaves.

ISOLASI DAN IDENTIFIKASI KHAMIR PENGHASIL ASAM INDOL ASETAT DARI RHIZOSFER ANGGREK TANAH Pecteilis susannae (L.) Rafin

The objectives of this study were to isolate and identify yeast producing Indole-3-acetic acid from rhizosphere of terrestrial orchid Pecteilis susannae (L.) Rafin. This research commenced with the isolation of yeasts from rhizosphere of orchid P. susannae using Yeast Malt Agar (YMA) medium. Yeast isolates were selected based on growth experiment on Glucose Peptone Broth (GPB) supplemented with 200 µg/mL L-tryptophan. The IAA concentration was determined colorimetrically on spectrophotometer (OD530 nm) with Salkowsky’s reagent added to supernatant of yeast culture. Biomass (OD600 nm) and IAA production (OD530 nm) measured every 24 hours for 4 days. Identification of selected isolates carried out through macroscopic, microscopic, and biochemical properties. The results revealed that 29 isolates of yeast had been successfully isolated from rhizosphere of terrestrial orchid P. susannae (L.) Rafin, and only four isolates (K2, U5, A3 and A1) showed their capability to grow and produce high concentration of IAA on GPB. The fourth selected yeast isolates were identified as strain Saccharomyces sp.1 (K2), Saccharomyces sp.2 (U5), Cryptococcus sp.1 (A3), and Candida sp.1 (A1). Further evaluation of the selected rhizosphere yeast isolated producing IAA is necessary to be carried out to explore their potency as a source of hormone to promote plant growth.

Critical analysis of the maximum non inhibitory concentration (MNIC) method in quantifying sub-lethal injury in Saccharomyces cerevisiae cells exposed to either thermal or pulsed electric field treatments

Sub-lethal injury within a microbial population, due to processing treatments or environmental stress, is often assessed as the difference in the number of cells recovered on non-selective media compared to numbers recovered on a “selective media” containing a predetermined maximum non-inhibitory concentration (MNIC) of a selective agent. However, as knowledge of cell metabolic response to injury, population diversity and dynamics increased, the rationale behind the conventional approach of quantifying sub-lethal injury must be scrutinized further. This study reassessed the methodology used to quantify sub-lethal injury for Saccharomyces cerevisiae cells (≈ 4.75 Log CFU/mL) exposed to either a mild thermal (45°C for 0, 10 and 20min) or a mild pulsed electric field treatment (field strengths of 8.0–9.0kV/cm and energy levels of 8, 14 and 21kJ/kg). Treated cells were plated onto either Yeast Malt agar (YM) or YM containing NaCl, as a selective agent at 5–15% in 1% increments. The impact of sub-lethal stress due to initial processing, the stress due to selective agents in the plating media, and the subsequent variation of inhibition following the treatments was assessed based on the CFU count (cell numbers). ANOVA and a generalised least squares model indicated significant effects of media, treatments, and their interaction effects (P<0.05) on cell numbers. It was shown that the concentration of the selective agent used dictated the extent of sub-lethal injury recorded owing to the interaction effects of the selective component (NaCl) in the recovery media. Our findings highlight a potential common misunderstanding on how culture conditions impact on sub-lethal injury. Interestingly for S. cerevisiae cells the number of cells recovered at different NaCl concentrations in the media appears to provide valuable information about the mode of injury, the comparative efficacy of different processing regimes and the inherent degree of resistance within a population. This approach may provide similar information for other micro-organisms.

English

In this paper, we did some preliminary characterization of six slow growing rhizobial strains, isolated from Retama monosperma (L.) Boiss. root nodules sampled from 3 sites along the coast of Oran (CapeFalcon, Bousfer and MersElHadjadj) in Northwestern Algeria. Results of this study showed that all strains had a very slow growth rate in yeast malt (YM) agar medium, forming colonies less than 1 mm in diameter after seven days incubation. Catalase, oxidase and urease were positive, 3-ketolactose was negative. All strains resisted alkaline pH up to 9 and salinity equal to 2% (w/v) NaCl. They grew from 14 to 30&deg;C with optimum growth at 28&deg;C which is related to their place of presence (marine sand dunes Mediterranean climate). The strains used are, on the one hand D-glucose and D-galactose as carbon source and on the other hand L-leucine, L-tyrosine as nitrogen source. The nodulation tests performed pointed out that the total dry weight of the plant could go up to 1.7 g per plant and the maximum number of nodules was equal to 5.6 nodules per plant for the strain RMB1 from Bousfer site. The intrinsic antibiotic resistance level in all strains was tested against nine antibiotics; they revealed a variability of resistance against spectinomycin (10 &micro;g,&nbsp;erythromycin (15 &micro;gml-1, rifampicin (30 &micro;gml-1), streptomycin (500 &micro;gml-1), kanamycin (30 &micro;gml-1), naldixic acid (30 &micro;gml-1), penicillin (6 &micro;gml-1) and tetracycline (30 &micro;gml-1) except for gentamycin (500 &micro;gml-1). The results of electrophoresis on 0.7% agarose gel showed the presence of chromosomal DNA and absence of plasmids. &nbsp; Key words: Retama monosperma (L.) Boiss., Bradyrhizobium, symbiosis, root nodules, nitrogen fixation, endemic legumes, Algeria.

Culture conditions for mycelial growth of Poria cocos

This study was carried out to determine the basic mycelial culture conditions for Poria cocos growth. According to colony diameter and mycelial density, suitable media for mycelial growth were Malt yeast extract, Potato dextrose agar, Yeast extract agar, and Yeast malt agar. The optimum temperature for mycelial growth was between 25 and <TEX>$35^{\circ}C$</TEX>, and the optimum pH value was between 4 and 7. Carbon and nitrogen sources were fructose and yeast extract. The optimum C/N ratio was about 10 to 1 with 2% glucose. Other minor components for optimal growth were thiamine-HCl and nicotinamide as vitamins, acetic and lactic acid as organic acids, and <TEX>$MgSO_4{\cdot}7H_2O$</TEX> and <TEX>$FeSO_4{\cdot}7H_2O$</TEX> as mineral salts.

Exploration of Potential Actinomycetes from CIFOR Forest Origin as Antimicrobial, Antifungus, and Producing Extracellular Xylanase

&lt;p&gt;This study aimed to isolate and explore the actinomycetes of CIFOR forest origin as an antimicrobial and antifungal agent, to produce an extracellular xylanase, and to identify isolates based on 16S rRNA gene sequences. Actinomycetes were isolated using Humic-acid Vitamin-B agar (HV) media. Actinomycetes colonies that grow on the medium HV was subsequently purified by growing them on yeast malt agar (YMA) media), then an antagonistic test of selected bacteria against Bacillus sp., Escherichia coli, Fusarium oxysporum, and Sclerotium sp was performed. Xylanase activity test was detected by observing a clear zone, followed by identification. Total of 35 isolates of actinomycetes isolated based on their colony morphology characteristics and diverse types of spore chains showed Streptomyces spp. of isolates CFR-06, CFR-15, CFR-17, CFR-18, and CFR-19 were able to inhibit the growth of Bacillus sp.. The highest inhibition zone has a diameter of 10.1 mm (isolate CFR-17). Isolates CFR-01 and CFR-15 were able to inhibit the growth of E. coli with the highest inhibition zone diameter of 5.1 mm (isolate CFR-15). Isolates CFR-29 and CFR-12 were able to inhibit the growth of F. oxysporum while isolate CFR-35 were able to inhibit the growth of Sclerotium sp.. Xylanase activity test showed that isolates CFR-12, CFR-20, CFR-22, CFR-24, CFR-25, CFR-30, CFR-33, CFR-34 have an ability to produce extracellular xylanase enzyme. Actinomycetes isolate (Xyl_22) as a potential xylanase enzyme producer was closely related with Streptomyces drozdowicii by the maximum similarity of 99%.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;How to Cite&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;Sipriyadi, S., Lestari, Y., Wahyudi, A., &amp;amp; Meryandini, A. (2016). Exploration Potential CIFOR Forest actinomycetes origin as Antimicrobial, Anti Fungus and Producing Enzymes Extracellular Xylanase. &lt;em&gt;Biosaintifika: Journal of Biology &amp;amp; Biology Education&lt;/em&gt;, 8(1), 94-102.&lt;/p&gt;

Atlantic salmon physiological and immune response to amoebic gill disease and insight into the biology of the amoeba

Amoebic gill disease (AGD) is an emerging disease in North European Atlantic salmon (Salmo salar) aquaculture caused by the amoeba Paramoeba perurans. Non-optimal environmental conditions such as increasing water temperature may affect AGD progression. To understand the role of predisposing environmental conditions on the biology of the parasite and on the host physiological and immune response, different clonal cultures of P. perurans and AGD infected Atlantic salmon were exposed, respectively, in vitro and in vivo to two different temperatures, 10°C and 15°C. Outputs from the in vitro experiment are 1) an improved understanding of the impact of temperature on amoebae growth rate during conditions that potentially influence disease development and 2) characterisation of changes in bacterial communities at different temperatures for different clonal cultures. Negative binomial analysis in R (R software, version 3.0.1) showed significant differences in growth rate among clonal cultures over time. Moreover, for each clonal culture, the fraction of amoebae in suspension in seawater showed a higher increase over time at 10°C, whereas the fraction of amoebae attached to the malt yeast agar (MYA) showed a higher increase over time at 15°C. 16S MiSeq analysis was also performed to characterise the changes in bacterial communities present in the cultures at the two different temperatures of the in vitro experiment. The host physiological and immune response to AGD infection during predisposing seasonal weather conditions (summer period) is still not well understood. Atlantic salmon smolts were exposed in vivo to the same temperatures used for the in vitro experiment, 10°C and 15°C, and to an initial concentration of 5000 cells l of a clonal culture of P. perurans for 3 weeks. Analyses of cortisol, glucose, and lactate concentration in plasma samples, white blood cell (wbc) differential count in blood smears, and gene expression have been performed at different time points after the challenge. The present results from the temperature dependent AGD infection and in vitro P. perurans growth rate studies hint that increased AGD outbreaks during summer periods may not be solely due to increased thermal stress in fish but also to increased amoebae attachment at 15°C which cause an increased gill pathology.

The first isolation of Trichosporon coremiiforme from soil in Iran.

Background and Purpose: Trichosporon is a genus of anamorphic basidiomycetous yeast which is widely distributed in nature and is found in tropical and temperate areas. The aim of this work was to study the isolation, identification and molecular analysis of Trichosporon species in soil.Materials and Methods:In order to isolate and identify Trichosporon species in soil, 30 samples were collected from 30 different locations across Iran. The isolates were identified by means of the standard methods of yeast identification. To confirm morphological identification, genomic DNA was extracted and the hypervariable D1/D2 domain of the large-subunit (LSU) ribosomal DNA (rDNA) gene was amplified by polymerase chain reaction (PCR), using primer pair NL-1/NL-4, and then the sequences were analyzed. Results:According to the morphological and physiological assessments, isolates were identified as T. coremiiforme. The isolates formed chlamydospore after one week on yeast-malt (YM) agar medium. Using Blast program, we found that the D1/D2 sequences of the T. coremiiforme isolates from Iran (accession no: KP055040 and KP055041) showed 99% homology with the T. coremiiforme deposited in GenBank. All the T. coremiiforme isolates placed in the Ovoides cluster were well-supported by bootstrap values.Conclusion:The present study is the first attempt to survey Trichosporon in soil of Iran. To the best of our knowledge, this is the first investigation of T. coremiiforme in Iran.

Substratum preference of two species of Xanthoparmelia

The distribution of established saxicolous lichens has been previously studied but substratum preference and elemental composition has been relatively unexplored. The objectives of this study were to compare ascospore germination and growth for two species of Xanthoparmelia using media supplemented with pulverized rock and to explore photobiont selectivity relative to ecological guilds. Mature apothecia from X. cumberlandia and X. viriduloumbrina were subjected to five treatments, which include water agar supplemented with crushed granodiorite, basalt, mica schist, dolostone, and malt yeast agar as the control. The algal actin gene was sequenced and the closest algal matches were retrieved from GenBank and analysed to produce a haplotype network. X. cumberlandia exhibited substratum preference for the mica schist treatment, while X. viriduloumbrina grew better on granodiorite and malt yeast agar relative to dolostone. Ascospore germination for both species failed to progress beyond the initial swelling and protrusion stage on the dolostone treatment. The actin gene sequences for the algae were most similar to those of Trebouxia jamesii. The rock substrates did not correspond with the photobiont haplotypes, which does not support the ecological guild hypothesis. This study provided insights into substratum preference and the suitability of the substratum for algal selection.

First morphogenetic identification of Fusarium solani isolated from orange fruit in Egypt

Losses due to post harvest decay may occur at any time during post harvest handling, from harvest to consumption affecting the produce quality and quantity. Accurate identification of the pathogen causing post harvest disease is essential to the selection of an appropriate disease control approach. Nine isolates of Fusarium recovered from orange fruit were identified as Fusarium solani. The fungus is involved with fruit decay. The obtained cultures were purified and grown on potato-dextrose agar (PDA), malt yeastagar (MYA), and Czapek's nutrient media (CNM) under light for identification. A pathogenicity test was carried out to fullfil Koch'spostulates. The pathogen could only enter ripe orange fruit through wounds and cracks causing the rot disease. The identification of the fungal isolates was confirmed to be F. solani by DNA sequencing, which was 99 to 100% homologous to those deposited in the Gen-Bank. The identity of nine fungal isolates was confirmed to be F.solani by DNA sequencing of the internal transcribed spacer (ITS) rDNA region (GenBank Accession Nos. DQ486874 to DQ486881 and KC758879). To our knowledge, this is the first morphogenetic identification of F. solani isolated from orange fruit in Egypt.

Microbial lipid production by oleaginous yeast Cryptococcus sp. in the batch cultures using corncob hydrolysate as carbon source

To realize the feasibility of biodiesel production from high-lipid cell culture, microbial lipid production by the oleaginous yeasts was studied using glucose and sucrose as carbon source. Among the tested strains, Cryptococcus sp. SM5S05 accumulated the highest levels of intracellular lipids. The crude lipid contents of Cryptococcus sp. cultured in yeast malt agar reached 30% on a dry weight basis. The accumulation of lipids strongly depended on carbon/nitrogen ratio and nitrogen concentration. The highest content of lipids, measured at a carbon/nitrogen ratio of 60–90 and at a nitrogen concentration of 0.2%, was 60–57% lipids in the dry biomass. Batch cultures using corncob hydrolysate demonstrated that there was minimal inhibitory effect with a reducing sugar concentration of 60 g l−1 or higher. Batch cultures of Cryptococcus sp. SM5S05 in the corncob hydrolysate medium with 60 g l−1 glucose resulted in a dry biomass, lipid yields, and content of 12.6 g l−1, 7.6 g l−1, and 60.2%, respectively. The lipids contained mainly long-chain saturated and unsaturated fatty acids with 16 and 18 carbon atoms. The fatty acid profile of Cryptococcus oils was quite similar to that of conventional vegetable oil. The cost of lipid production could be further reduced with corncob hydrolysate being utilized as the raw material for the oleaginous yeast. The results showed that the microbial lipid from Cryptococcus sp. was a potential alternative resource for biodiesel production.