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Abstract: Deterioration in heritage wood structures caused by wood-decay fungi is a worldwide concern. In the University of the Philippines Los Baños, decay fungi from wooden canopies of the Baker Memorial Hall were identified and its degrading ability was evaluated. Specimen collection was conducted on degraded canopies made of Mayapis (Shorea palosapis) with signs of white or green fungal growth. Fungi associated with the rotting symptoms were isolated, purified, characterized and identified. Colonies of fungal isolates were fast-growing in malt extract agar (MEA), with colony diameter reaching 5.60 % 0.43 cm (WRF8) and 5.15 % 0.25 cm (WRF5) after a day. Mycelia of isolates were hyaline and rhizoidal on water agar. Isolate WRF5 produced green, raised colonies that imparted yellow pigmentation on potato dextrose agar (PDA) and MEA. Generally, colonies were raised, radially striated with green center and white margin on PDA. Average length and width of WRF5 conidia were 3.19 % 0.33 %m and 2.73 % 0.36 %m, respectively. Cross-referencing morphological and cultural data with related literatures and identification keys indicated the isolated fungi were Trichoderma viride (WRF1), T. crassum (WRF3), T. reesei (WRF5), Rhizopus sp. (WRF8) and Coniophora sp. Furthermore, inoculation of 108 T. reesei conidia/mL on clean Mayapis wood blocks resulted to profuse fungal growth, with average weight loss recorded at 8.81 % 0.79% at 8 wks and 10.53 % 0.88% at 14 wks which indicated a considerable but slow wood degradation.
Published in DiRROS: 31.07.2024; Views: 255; Downloads: 160
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Abstract: Potato virus Y (PVY) is the most economically important potato virus, therefore extensive research is focusing on elucidation of its interaction with the host. To obtain repeatable results, strict standardization of research methods is crucial. Mechanical inoculation by rubbing sap from a PVY infected plant onto the leaf surface together with a fine abrasive powder is the most convenient way of experimental transmission of PVY to host plants. However, factors determining reproducibility of this process need to be determined. In the present study, it was shown that higher titre of the virus in the inoculum resulted in faster increase of PVYNTN RNA titre in the inoculated leaves, as well as in faster translocation of PVYNTN from inoculated leaves into upper non-inoculated leaves. The final titre of PVYNTN RNA in upper non-inoculated leaves was independent of the virus titre in the inoculum. In addition, the occurrence of the disease symptoms was followed and the dependence to the titre of the virus in the inoculum was observed.
Keywords: krompir, virus krompirja Y, mehanska inokulacija, titer virusa, inokulum, Potato virus Y, PVY, potato, mechanical inoculation, inoculum, virus titre, symptoms
Published in DiRROS: 31.07.2024; Views: 282; Downloads: 179
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Abstract: A checklist of the dragonflies and damselflies occurring in Bangladesh, Bhutan, India (including Andaman and Nicobar Islands), Nepal, Pakistan and Sri Lanka is presented. In total 588 (including 559 full species) taxa are known to occur in the region of which 251 taxa (species & subspecies) are single country endemics. Recent taxonomic changes relevant to the area are summarized. Sixteen taxa are synonymized and a checklist of all synonyms established since 1950 is provided. Information is given on available larval descriptions including a list of genera present in the region for which no larvae have yet been described. Numerous species occurring in the area are still poorly known and a list of genera for which a revision is urgently needed is provided. The following new synonyms are established: Calicnemia sudhaae Mitra, 1994 = Calicnemia imitans Lieftinck, 1948 syn. nov.; Ceriagrion fallax cerinomelas Lieftinck, 1927 = Ceriagrion fallax Ris, 1914 syn. nov.; Ceriagrion fallax pendleburyi Laidlaw, 1931 = Ceriagrion fallax Ris, 1914 syn. nov.; Coenagrion kashmirus Chowdhary & Das, 1975 = Ischnura forcipata Morton, 1907 syn. nov.; Enallagma insula Fraser, 1920 = Aciagrion occidentale Laidlaw, 1919 syn. nov.; Himalagrion pithoragarhicum Sahni, 1964 = Ceriagrion fallax Ris, 1914 syn. nov.; Ischnura bhimtalensis Sahni, 1965 = Ischnura rubilio Selys, 1876 syn. nov.; Onychargia indica Sahni, 1964 = Paracercion calamorum (Ris, 1916) syn. nov.; Anaciaeschna kashmirense Singh & Baijal, 1954 = Anaciaeschna martini (Selys, 1897) syn. nov.; Cyclogomphus vesiculosus Selys, 1854 = Cyclogomphus ypsilon Selys, 1954 syn. nov.; Chlorogomphus brittoi Navás, 1934 = Chlorogomphus xanthoptera (Fraser, 1919) syn. nov.; Hylaeothemis indica Fraser, 1946 = Hylaeothemis apicalis Fraser, 1924 syn. nov.; Sympetrum durum Bartenef, 1916 = Sympetrum striolatum commixtum Selys, 1884 syn. nov.; Sympetrum himalayanum Navás, 1934 = Sympetrum hypomelas (Selys, 1884) syn. nov.; Sympetrum haematoneura Fraser, 1924 = Sympetrum speciosum Oguma, 1915 syn. nov.; Sympetrum speciosum taiwanum Asahina, 1951 = Sympetrum speciosum Oguma, 1915 syn. nov. In addition, Periaeschna lebasi Navás, 1930 is regarded a nomen nudum. The following new combinations are proposed: Onychogomphus acinaces Laidlaw, 1922 is transferred to the genus Melligomphus Chao, 1990 resulting in Melligomphus acinaces (Laidlaw, 1922) comb. nov. Onychogomphus saundersii Selys, 1854 is transferred to the genus Nychogomphus Carle, 1986 resulting in Nychogomphus saundersii (Selys, 1854) comb. nov..
Keywords: damselfly, dragonfly, diversity, taxonomy, larval description, Indian subcontinent, South Asia
Published in DiRROS: 31.07.2024; Views: 251; Downloads: 213
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Abstract: Detailed investigation of photocatalyzed degradation of dibutyl phthalate (DBP), an endocrine disrupter, in the presence of α-FeOOH (goethite) and different carboxylic acids is the focus of this study. To get a better insight into the efficiency of the degradation, the influence of different parameters, such as concentration of total Fe and Fe(II), dissolved oxygen, DBP concentration, pH and salinity is investigated. The reaction mechanism consists of several interrelationship steps. The first step is the chemical reaction of carboxylic acid groups of the organic acids with hydroxyl groups of the α-FeOOH and a charge transfer upon illumination generating Fe(II). The second step is the release of Fe(II) into the solution followed by H2O2 oxidation to form highly photoactive hydroxyl complex of iron(III) and ˙OH. Simultaneously, the superoxide radical O2˙− and hydroperoxyl radical is formed in acidic solutions in presence of carboxylic acids as well. This mechanism explains the genesis of different reactive species oxidizing DBP. From the variety of the studied carboxylic acids (oxalic, citric, salicylic, pyruvic, maleic, and fumaric), oxalic acid is the best Fe-ligand for the photoreductive dissolution of goethite. Concentrations of the total amount of Fe and its dissociated forms Fe(II) as well as oxygen and hydroxyl radicals play a fundamental role in efficiency of DBP degradation. The photodegradation of DBP with goethite and the use of suitable carboxylic acids under optimized reaction conditions could be an efficient process for decontamination of polluted waters.
Keywords: photocatalysis, goethite, dibutyl phthalate, carboxylic acid, water treatment
Published in DiRROS: 31.07.2024; Views: 289; Downloads: 240
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Abstract: The presence of plastics in the environment is currently one of the most pressing global environmental problems. Microorganisms start to form biofilms on plastic surfaces when they first come in contact with the biosphere; however, these interactions and processes are little understood, especially in freshwaters. This study aimed to better understand the colonization process of microorganisms from activated sludge on plastic materials exhibiting different surface characteristics. We inoculated synthetic fabric (PET), water bottles (PET), and plastic bags for packing vegetables and fruits (HDPE) with microorganisms from activated sludge. Mixtures of plastics and activated sludge, as well as the control, were incubated at 22-24°C in Bushnell Haas (BH) liquid medium and shaken at 120 rpm for two months. The mixtures were sub-sampled weekly and seeded into fresh BH medium with test plastic materials to avoid feeding microorganisms on dead biomass. The colonization was followed by measuring optical density (OD600) of liquid medium, by measurements of isotopic composition of carbon (δ13C) in untreated and treated plastic materials and, with in-specting the plastics surface with scanning electron microscopy (SEM). Overall, the study confirmed differences between colonizing microorganisms on different plastic material when comparing SEM micrographs of materials from the flasks inoculated with activated sludge. The texture of the HDPE bag changed during the experiment in both, control and inoculated flasks, but it is not clear whether the observed changes were due to abiotic or biotic factors. We concluded that microorganisms from activated sludge are capable of colonizing both PET and HDPE materials, and biofilm formation is most probably influenced by the chemical composition of plastics and their surface characteristics.
Keywords: biofilm, plastics, SEM, isotopic composition of carbon, co-cultivation, UV sterilization
Published in DiRROS: 31.07.2024; Views: 328; Downloads: 246
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