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1.
Lipase production by Candida rugosa was carried out in submerged fermentation. Plackett-Burman statistical experimental design was applied to evaluate the fermentation medium components. The effect of twelve medium components was studied in sixteen experimental trials. Glucose, olive oil, peptone and FeCl3?6H2O were found to have more significance on lipase production by Candida rugosa. Maximum lipase activity of 3.8 u mL-1 was obtained at 50 h of fermentation period. The fermentation was carried out at optimized temperature of 30oC, initial pH of 6.8 and shaking speed of 120 r/min. Unstructured kinetic models were used to simulate the experimental data. Logistic model, Luedeking-Piret model and modified Luedeking-Piret model were found suitable to efficiently predict the cell mass, lipase production and glucose consumption respectively with high determination coefficient(R2). From the estimated values of the Luedeking-Piret kinetic model parameters, α and β, it was found that the lipase production by Candida rugosa is growth associated.  相似文献   
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We studied extent and type of arbuscular mycorrhizal (AM) and septate endophytic (SE) fungal associations in five lycophytes and 50 ferns collected from Eastern and Western Ghats regions. Of the 54 species and one variety (belonging to 31 genera) examined; 54 taxa had AM association and AM fungal structures were absent in Marsilea quadrifolia. This is the first report of AM and SE fungal status for 26 species each. Of the 55 taxa examined, AM morphology has been evaluated for the first time in 51 species. The hydrophytic fern Salvinia molesta was mycorrhizal and non-mycorrhizal at different sites. All the epiphytic and saxicolous species examined were mycorrhizal. The percentage of AM colonization ranged from 22.23 (Christella parasitica) to 82.20 (Adiantum lunulatum) in ferns and 53.46 (Selaginella bryopteris) to 84.34 (Selaginella sp.) in lycophytes. Epiphytic life-forms had the maximum average AM colonization levels, whereas aquatic life-forms had the minimum colonization levels. The percentage root length colonized by septate fungi ranged between 0.59 in Ophioglossum reticulatum and 16.36 in Pteris pellucida. The root length with AM and SE fungal structures as well as their total colonization significantly varied among the taxa examined. Most of the lycophytes and ferns had intermediate-type of AM morphology with a few exhibiting Paris-type. AM fungal spore numbers ranged from 1.0 (Angiopteris evecta, Pteridium aquilinum) to (Nephrolepis exaltata) 9.3 spores per 25 g soil and varied significantly among taxa. AM fungal spore morphotypes belonging to Claroideoglomus, Funneliformis, Glomus and Rhizophagus were recorded.  相似文献   
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Sponges invariably filter a large volume of seawater and potentially accumulate heavy metals and other contaminants from the environment. Sponges, being sessile marine invertebrates and modular in body organization, can live many years in the same location and therefore have the capability to accumulate anthropogenic pollutants such as metals over a long period. Almost all marine sponges harbor large number of microorganisms within their tissues where they reside in the extra- and intra-cellular spaces. Bacteria in seawater have already been established as biological indicators of contamination. The present study was intended to find out the heavy metal resistance pattern of sponge-associated bacteria so as to develop suitable biological indicators. The bacteria associated with a marine sponge Fasciospongia cavernosa were evaluated as potential indicator organisms. The associated bacteria including Streptomyces sp. (MSI01), Salinobacter sp. (MSI06), Roseobacter sp. (MSI09), Pseudomonas sp. (MSI016), Vibrio sp. (MSI23), Micromonospora sp. (MSI28), Saccharomonospora sp. (MSI36) and Alteromonas sp. (MSI42) showed resistance against tested heavy metals. Based on the present findings, Cd and Hg emerged as the highly resistant heavy metal pollutants in the Gulf of Mannar biosphere reserve. Plasmids in varied numbers and molecular weights were found in all the isolates. Particularly the isolates MSI01 and MSI36 harbored as many as three plasmids each. The results envisaged that the plasmids might have carried the resistance factor. No correlation was observed in number of plasmids and level of resistance. The literature evidenced that the sponge-associated bacteria were seldom exploited for pollution monitoring though they have been extensively used for bioprospecting. In this background, the present findings come up with a new insight into the development of indicator models.  相似文献   
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The effect of Pseudomonas fluorescens treatment and Fusarium oxysporum f. sp. cubense inoculation on induction of phenylalanine ammonia-lyase (PAL), peroxidase (POX), chitinase, -1,3-glucanase and accumulation of phenolics in banana (Musa sp.) was studied. When banana roots were treated with P. fluorescens strain Pf10, a two-fold increase in phenolic content in leaf tissues was recorded 3 – 6 d after treatment. Challenge inoculation with F. oxysporum, the wilt pathogen, steeply increased the phenolic content in P. fluorescens-treated banana plants. Significant increase in POX activity was detected 6 – 9 d after P. fluorescens treatment. PAL, chitinase and -1,3-glucanase activities increased significantly from 3 d after P. fluorescens treatment and reached the maximum 6 d after treatment. Challenge inoculation with F. oxysporum further increased the enzyme activities. These results suggest that the enhanced activities of defense enzymes and elevated content of phenolics may contribute to bioprotection of banana plants against F. oxysporum.  相似文献   
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HAPPY mapping is an in vitro approach for defining the order and spacing of DNA markers directly on native genomic DNA. This cloning-free technique is based on analysing the segregation of markers amplified from high molecular weight genomic DNA which has been broken randomly and 'segregated' by limiting dilution into subhaploid samples. It is a uniquely versatile tool, allowing for the construction of genome maps with flexible ranges and resolutions. Moreover, it is applicable to plant genomes, for which many of the techniques pioneered in animal genomes are inapplicable or inappropriate. We report here its demonstration in a plant genome by reconstructing the physical map of a 1.9 Mbp region around the FCA locus of Arabidopsis thaliana. The resulting map, spanning around 10% of chromosome 4, is in excellent agreement with the DNA sequence and has a mean marker spacing of 16 kbp. We argue that HAPPY maps of any required resolution can be made immediately and with relatively little effort for most plant species and, furthermore, that such maps can greatly aid the construction of regional or genome-wide physical maps.  相似文献   
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To find out the genetic diversity of Indian Foc isolates of banana, a total of 107 isolates of Fusarium which includes 98 Foc isolates obtained from different banana growing regions of India and seven Foc isolates belong to all known VCGs obtained from Australia and two non-pathogenic Fusarium oxysporum (npFo) isolates were subjected to ISSR analysis. In the initial screening of ISSR primers, out of 34, 10 primers which generated more polymorphic bands were selected for further analysis. The Phylogenetic analysis carried out based on the fingerprints obtained through ISSR analysis indicated the presence of wide genetic diversity among the Foc isolates of India and also its polyphyletic nature. Totally, seven different clusters were obtained and these clusters differentiated the Foc isolates of India based on the races/VCGs. Besides, the cluster analysis clearly distinguished the freshly emerged Foc strain obtained from cv. Grand Naine (Cavendish-AAA) and Poovan (Mysore-AAB) from the other Foc isolates. The non-pathogenic F. oxysporum isolates which have been included for comparison purpose also clustered separately. All these above said findings indicates for the first time the discriminatory power of ISSR to clearly distinguish and separate the Foc isolates according to its race/VCGs and also its virulence. This study would be useful not only to design and develop effective management strategies but also useful for quarantine purposes.  相似文献   
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Fusarium wilt caused by Fusarium oxysporum f. sp. cubense (Foc) is considered as a lethal disease of bananas worldwide. To manage the disease effectively, 20 rhizospheric and 43 endophytic Trichoderma isolates obtained from 12 different Foc resistant banana accessions were evaluated against Foc in vitro and in vivo. In vitro screening among Trichoderma isolates for their multiple functions (mycelial and spore germination inhibition, hydrogen cyanide, chitinolytic enzymes, non-volatile and volatile metabolites production) in suppressing Foc and promoting plant growth (IAA production and phosphate solubilisation) indicated that the multiple biocontrol actions were significantly higher in 6 isolates of rhizospheric Trichoderma and 10 isolates of endophytic Trichoderma compared to other isolates. The greenhouse evaluation of individual application of these rhizospheric and endophytic Trichoderma isolates against Fusarium wilt pathogen in cv. Grand Naine (AAA) indicated significant suppression of Fusarium wilt disease and increased plant growth characters as compared to Foc pathogen inoculated plants. However, none of these individual Trichoderma isolates recorded complete suppression of Fusarium wilt disease. Therefore, the greenhouse evaluation involving combination of rhizospheric Trichoderma sp. NRCB3 + endophytic Trichoderma asperellum Prr2 recorded 100% reduction of Fusarium wilt disease and increased plant growth parameters up to 250% when compared to individual isolates application and Foc alone-inoculated plants. Further, the field evaluation of this combination of Trichoderma isolates applied for three times: (1) at 15 days before planting, (2) second month after planting and (3) fourth month after planting resulting in significant reduction of Fusarium wilt disease and also increase in bunch weight as compared to untreated control plants. Therefore, these Trichoderma isolates may be used in combination for the effective suppression of Fusarium wilt disease in banana.  相似文献   
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