Antisopp aktivitet av kitosan/chitooligosakkarider alene og i kombinasjon med kjemiske fungicider mot sopp-patogener

Botrytis cinerea Pers. ex Fr. is an economically important pathogen causing gray mold in over 200 plants species worldwide, including strawberry (Fragaria × ananassa). In Norway, gray mold is economically the most important disease on strawberry and may cause 30-60% yield loss. In Bangladesh, the main constraint of chickpea production is attack by B. cinerea, which may cause up to complete yield loss. Thus farmers are highly concerned to control this disease but they are mainly dependent on commercially available chemical fungicides. In developing countries like Bangladesh, farmers use excessive amounts of chemical fungicides to control B. cinerea without having safety knowledge about chemical fungicides and this creates health, environmental and disease resistance problems. This PhD project studied chitosan and chitooligosaccharides (CHOS) as alternatives and means to reduce the use of chemical fungicides without reduced efficacy. Chitosan or CHOS alone and mixtures of chitosan or CHOS combined with reduced amounts of chemical fungicides were tested in vitro (in microtiter plates) and in vivo (strawberry flower, chickpea and bean leaf assays) against B. cinerea. Chitosan is a biopolymer obtained by partial deacetylation of chitin. The antifungal activity of chitosan depends on factors (Paper I) such as the fraction of acetylation (FA) (chitosan with low FA was more inhibitory to B. cinerea than high FA), the pH and cations present in the media (the antifungal activity of chitosan with low FA was higher at pH 6 than 3-5 and increasing Ca2+ and Mg2+ concentrations in the media reduced the ability of chitosan to inhibit B. cinerea). The antifungal activity of chitosan also depended on the average degree of polymerization (DPn) CHOS with DPn 23 and 40 were the most effective inhibiting germination of all tested pathogens. Mucor piriformis and B. cinerea BCBD were sensitive (in terms of germination inhibition) to a wide range of CHOS (DPn 75, 58, 48, 40, 15; DPn 40, 23, 15 and 11 respectively), but B. cinerea BC 101 was only inhibited by DPn 23-40 (Paper III). As chitosan or CHOS alone were not as effective as chemical fungicides, the combination of chitosan or CHOS with chemical fungicides were tested to control B. cinerea in vitro and in vivo (Paper II and VI). Our study showed that both chitosan and CHOS showed synergism (in terms of inhibiting B. cinerea) with chemical fungicides and CHOS were more effective than chitosan. In vitro, CHOS showed high levels of synergism with all tested fungicides, i.e. CHOS DPn 23 (5 μg mL-1), Amistar and Signum (10 μg mL-1) alone only showed 2-4% germination inhibition of B. cinerea BC 101, but the combinations of CHOS and Amistar or CHOS and Signum, in the aforementioned concentrations and DPn, showed >90% germination inhibition. Chitosan (DPn 206) only showed low levels of synergism with Teldor and Switch. In vivo bioassay of strawberry flowers and chickpea leaves showed a similar trend as in vitro where CHOS showed more synergism with chemical fungicides than chitosan (DPn 206) in inhibiting B. cinerea. However, there was no difference between chitosan and CHOS in combination with chemical fungicides to reduce bean leaf infection by B. cinerea. Our study suggested that CHOS used in combination with chemical fungicides could considerably reduce the need for chemical fungicides by enhancing their efficacy. Application of this knowledge in Integrated Pest Management programs against plant pathogens could reduce the need for chemical fungicides, thus causing less harm for the environment and human health.Botrytis cinerea Pers. ex Fr. er en økonomisk viktig patogen som forårsaker gråskimmel på over 200 plantearter over hele verden, deriblant jordbær (Fragaria × ananassa). I Norge, er gråskimmel den økonomisk viktigste sykdommen på jordbær og kan føre til 30-60% avlingstap. I Bangladesh, er det alvorligste problemet i kikkerter produksjonen, angrep av B. cinerea, som kan føre opp til totalt tap av avlingen. Bøndene er derfor svært opptatt av å kontrollere denne sykdommen og de er avhengig av å benytte kommersielt tilgjengelige kjemiske fungicider. I utviklingslandene som Bangladesh, bruker bøndene store mengder kjemiske fungicider for kontroll av B. cinerea uten å ha nødvendig sikkerhetsopplæring og dette skaper helse, miljø og sykdomsresistens problemer. I dette PhD prosjektet ble det undersøkt om kitosan og kitooligosakkarider (CHOS) kan være et alternativ for å redusere bruken av kjemiske fungicider uten å redusere sykdomskontrollen. Chitosan eller CHOS alene eller en blanding av kitosan eller CHOS kombinert med redusert mengde kjemiske fungicider ble testet in vitro (i mikrotiter plater) og in vivo (på jordbær blomster, kikkerter blad eller bønne blad) mot B. cinerea. Kitosan er en biopolymer fremstilt ved partsiell deasetylering av kitin. Antisopp aktivitet av kitosan er avhengig av faktorer (Paper I) slik som fraksjonen av acetylering (FA) (kitosan med lav FA var mer hemmende overfor B. cinerea enn kitosan med høy FA), pH og kationer tilstede i media (den antifungal aktivitet av kitosan med lav FA var høyere ved pH 6 enn ved 3-5 og økende Ca2+ og Mg2+ konsentrasjoner i media reduserte evne kitosan hadde til å inhibere B. cinerea). Antisopp aktivitet av kitosan er også avhengig av gjennomsnittlig grad av polymerisering (DPn) av kitosan. CHOS med DPn 23 og 40 var de mest effektive hemmere av spiring av alle testede patogener. Mucor piriformis og B. cinerea BCBD var følsomme (i form av spiring inhibering) til et bredt spekter av CHOS (DPn 75, 58, 48, 40, 15; DPn 40, 23, 15 og 11 henholdsvis), mens B. cinerea BC 101 bare ble hemmet av DPn 23-40 (Paper III). Fordi kitosan eller CHOS alene ikke var så effektive som kjemiske fungicider, ble blandinger av kitosan eller CHOS med kjemiske fungicider testet mot B. cinerea in vitro og in vivo. (Papir II og VI). Vår studier viste at både kitosan og CHOS hadde evnen til å vise synergisme (i form av å hemme B. cinerea) med kjemiske soppmidler og CHOS var mer effektiv enn kitosan. In vitro viste CHOS høye nivåer av synergisme med alle testede fungicider, dvs. mens CHOS DPn 23 (5 ug ml-1), Amistar og Signum (10 μg ml-1) alene bare viste 2-4% spiring hemming av B. cinerea BC 101, viste kombinasjoner av CHOS og Amistar eller CHOS og Signum, i de nevnte konsentrasjoner og DPN, > 90% spire hemming. Kitosan (DPn 206) viste lave nivåer av synergisme med Teldor og Switch. In vivo biotester med jordbær blomster og kikertblader viste en lignende trend som in vitro hvor CHOS var mer effektivt og vise større synergisme med kjemiske soppmidler enn kitosan (DPn 206) i hemning av B. cinerea. Imidlertid var det ingen forskjell mellom kitosan og CHOS i kombinasjon med kjemiske fungicider for å redusere infeksjon av bønneblader med B. cinerea. Vår studier viser at CHOS brukt i kombinasjon med kjemiske soppmidler kan redusere behovet for kjemiske soppmidler ved å styrke deres effekt. Anvendelsen av denne kunnskapen i Integrert plantevern (IPM) mot plantesykdommer kan redusere behovet for kjemiske soppmidler og dermed forårsaker mindre skade for miljøet og menneskers helse

Insight into Solvent Coordination of an Iron Porphyrin Hydroxylamine Complex from Spectroscopy and DFT Calculations

The reduction of Fe(OEP)(NO) in the presence of substituted phenols leads to a three‐electron reduction to form Fe(OEP)(NH2OH), which has been characterized by visible spectroscopy and electron stoichiometry. In this work, we have further characterized this species using infrared and 1H NMR spectroscopy, along with DFT calculations. The infrared bands in the 3400–3600 cm–1 region, due to hydroxylamine, were significantly downshifted to the 2500–2700 cm–1 region when 4‐[D1]chlorophenol replaced the normal abundance acid. Using 1H NMR spectroscopy, the hydroxylamine and the meso‐protons were identified. From DFT calculations, the 1H NMR spectra were most consistent with a six‐coordinate complex, Fe(OEP)(NH2OH)(THF)

FM and Web Based Solution: A Novel Approach to Monitor and Control Home Appliances using Mobile Phone

The capacity of controlling various electrical and electronics devices in a wireless and remote fashion has provided a great convenience to many people in life. Through a wireless distant control system, people can do remote operation without directly accessing the host of home appliances like fan, lamp, TV, washing machines and others. Pocket switch is one of these types of system which we can use to control home appliances smartly from anywhere. The main objective of this work is to make such a system which controls the home appliances remotely using Web service and FM technology from a mobile phone. This paper discusses two methods of controlling home appliances. The first one is web service based where server will generate a command to the controller computer and the second one is FM network based where server will synthesize the SMS in to speech

Redox and Spectroscopic Properties of Protonated Species of Iron Porphyrin Nitroxlys and Their Analogues

Nitrite reduction to ammonia or nitrous oxide involves a series of electron transfer and protonation steps which are carried out by assimilatory or dissimilatory nitrite reductases. In the assimilatory process, nitrite incorporated into the biomass while in the dissimilatory process, it is excreted from the cell and the reaction is a source of energy. The complexes that will be studied in this work are models for assimilatory (siroheme) and dissimilatory (heme d1 ) nitrite reductases. Iron porphyrin nitrosyls were reduced in the presence of weak acids such as phenol and substituted phenols. Voltammetric techniques such as cyclic and rotating ring disk electrode (RRDE) voltammetry were employed to elucidate the reduction/protonation reaction mechanism and kinetics. Cyclic voltammograms showed two closely spaced waves for the reduction of Fe(OEP)(NO) (OEP= octaethylporphyrin) in the presence of substituted phenols. The first wave corresponded to a single electron reduction and the second wave was a multielectron process which was kinetically controlled. To determine the kinetics of the first protonation, RRDE voltammetry on the first wave was studied. UV-visible spectroelectrochemistry was carried out to identify the protonated species that were formed. The results indicated that the two-protonated species were present, which were identified as Fe(OEP)(HNO) and Fe(OEP)(NH2OH). The formation of these two species was suppressed by adding the conjugate base of the substituted phenol to the solution. FTIR spectroelectrochemistry was also employed to confirm those protonated species. Fe(OEP)(HNO) and Fe(OEP)(NH2OH) were generated chemically and verified by UV-visible, FTIR and NMR spectroscopy. Other models showed similar behavior with slight differences. A series of iron corrole nitrosyl complexes were also studied. Even though the one electron reduction species were stable in both the voltammetric and spectroelectrochemical timescale, the protonation of reduced species was not observed in the experimental time scale

Redox and Spectroscopic Properties of Iron Porphyrin Nitroxyl in the Presence of Weak Acids

The spectroelectrochemistry and voltammetry of Fe(OEP) (NO) in the presence of substituted phenols was studied. Cyclic voltammetry showed that two closely spaced waves were observed for the reduction of Fe(OEP) (NO) in the presence of substituted phenols. The first wave was a single electron reduction under voltammetric conditions. The second wave was kinetically controlled, multielectron process. Visible spectroelectrochemistry of Fe(OEP) (NO) in the presence of substituted phenols showed that three species were present during the electrolysis. Additional spectroscopic studies indicated that the two reduction species were Fe(OEP) (HNO) and Fe(OEP)(H2NOH). The Fe(OEP) (HNO) species, which can be generated chemically, was stable over a period of hours. Additional acid did not lead to further protonation. Proton NMR spectroscopy confirmed the Fe(OEP) (HNO) species could be deprotonated under basic conditions. The third species, Fe(OEP)(H2NOH), was generated by the further reduction of the chemically generated Fe(OEP) (HNO) complex. Both the Fe(OEP) (HNO) and Fe(OEP)(H2NOH) complexes could be slowly oxidized back to Fe(OEP) (NO). At millimolar concentrations of Fe(OEP) (HNO), there was no evidence for the disproportionation of Fe(OEP) (HNO) to Fe(OEP) (NO) and H2 in the presence of substituted phenols. Nor was there evidence for the generation of N2O. The FTIR spectroelectrochemistry showed changes in the infrared spectra in the presence of substituted phenols, but no isotopic sensitive bands were observed for the reduced species between 1450 and 1200 cm–1. This may be because the νNO band shifted into a region (1500–1450 cm–1) where it would be difficult to observe

Catalytic Reduction of Bisulfite by Myoglobin/Surfactant Films

The voltammetry of bisulfite at a film formed with myoglobin was studied in aqueous solutions. A broad wave was observed for the reduction of bisulfite. Using controlled potential electrolysis, the reduction at potentials positive of the FeII/FeIwave formed dithionite exclusively. As the potential approached the region for the FeII/FeI reduction, bisulfite was reduced primarily to HS−. Even at the negative potentials, some dithionite was still formed, which could then be electrochemically reduced to thiosulfate. Analysis of the formation of HS−, dithionite and thiosulfate during the electrolysis was consistent with the parallel formation of HS−and dithionite, the latter of which was reduced to thiosulfate. Thiosulfate was verified by chemical analysis of the products from controlled potential electrolysis of the solution, and dithionite was observed spectroscopically using spectroelectro−chemistry

Investigating the role of the V. cholerae integron/gene cassette system in biofilm formation and resistance to protozoa

University of Technology Sydney. Faculty of Science.Vibrio cholerae is a marine aquatic bacterium and the causal agent of the devastating diarrhoeal cholera disease that sickens millions of people each year. Persistence in the environment of this pathogen causes periodical disease outbreaks. Biofilm formation by V. cholerae on abiotic or biotic surfaces including chitin surface act as a major reservoir in the environment that also induces the natural competency of this bacterium and allows the lateral gene transfer (LGT) through uptake of exogenous DNA. Chromosome 2 of V. cholerae carries an adaptive genetic element called the integron that contains more than 150 gene cassettes of which 80-90 % are of unknown function. Integration, deletion or rearrangement of gene cassettes is dependent on a recombinase called the integron-integrase (intIA) that is induced by the bacterial SOS response, which is activated by the presence of single-stranded DNA (ssDNA) due to stalled DNA replication from damage or from acquisition of ssDNA from LGT processes. In order to study chitin induced transformation and intIA transcription in V. cholerae, this thesis described the construction of circular and linear gene cassettes and investigated their transfer into the V. cholerae integron and demonstrating that the integron is a novel site for adding DNA for complementation of mutations in V. cholerae. Additionally, insertion of the artificial gene cassettes into attI and two different attC sites were shown to affect bacterial surface properties and biofilm formation. Finally, one of the artificial gene cassettes was used to investigate cassette transfer dynamics in V. cholerae in the presence of two bacteriovorist protozoa, the ciliate Tetrahymena pyriformis and the amoeba Acanthamoeba castellanii. This thesis shows that following internalization and packaging of V. cholerae into the food vacuoles of both protozoa, intracellular ROS induces the SOS response leading to enhanced integron-integrase expression and gene cassette recombination. In addition, this thesis shows that due to the indiscriminate feeding behaviour of protozoa, co-localisation of different species such as V. cholerae and E. coli in the same phagosome can facilitate LGT. It is shown that V. cholerae utilizes its T6SS to kill and release artificial gene cassette DNA from E. coli to make it accessible for uptake and subsequent integron-integrase mediated integration. Taken together, this thesis, through the creation of artificial gene cassettes to study integron integration dynamics, highlights the importance of integron-associated gene cassettes in biofilm formation and shows the importance of protozoa in driving LGT-driven adaptation and evolution in V. cholerae

Production of functional textile filaments from chemically modified cellulose fibers

Cellulose is the most abundant natural polymer on earth originated from renewable plant biomass. Among all plant sources, cotton fibers contain the highest amount of pure cellulose, which is used directly in textile fibers for yarn and fabric production. Cellulose fibers (more commonly referred to as pulp fibers) are extracted through various pulping processes to remove the lignin andC hemicellulose, which increases the overall alpha-cellulose contents. However, cellulose fibers have a lower aspect ratio and do not fulfill the technical requirements for textile and yarn production. However, the aspect ratio can be increased by dissolving the cellulose fibers in an appropriate solution to regenerate them for getting continuous filaments. Currently, cellulose regeneration processes require toxic chemical processes that are not environmentally friendly and required extensive pre-treatment. In this study, we developed a green method to produce textile filaments from existing kraft pulp (cellulose) fibers. The cellulose fibers were chemically modified to produce a low-substituted carboxymethylcellulose (CMC) and dialdehyde cellulose (DAC). The CMC and DAC gels were then extruded through a wet-spinning process to obtain cross-linked textile filaments. These filaments have a low content of carboxylic groups (∼1.4 mmol/g cellulose) and aldehyde groups (∼1.5 mmol/g cellulose) and underwent a significant reduction of water absorption with high mechanical strength. In this work, the degree of hydrophilicity of the produced filaments was optimized by controlling the functional groups (carboxyl and aldehyde). We also focus on other conditions that affect the hydrophilicity of the filaments to achieve similar absorption properties of cotton fabric (i.e., water uptake - 1.5 g/g yarn)

Absolutely Continuous Invariant Measures for Piecewise Convex Maps of Interval with Infinite Number of Branches

The main result of this Master's thesis is the generalization of the existence of absolutely continuous invariant measure for piecewise convex maps of an interval from a case with the finite number of branches to one with infinitely many branches. We give a similar result for piecewise concave maps as well. We also provide examples of piecewise convex maps with a finite and infinite number of branches without ACIM

Food Recognition and Volume Estimation in a Dietary Assessment System

Recently obesity has become an epidemic and one of the most serious worldwide public health concerns of the 21st century. Obesity diminishes the average life expectancy and there is now convincing evidence that poor diet, in combination with physical inactivity are key determinants of an individual s risk of developing chronic diseases such as cancer, cardiovascular disease or diabetes. Assessing what people eat is fundamental to establishing the link between diet and disease. Food records are considered the best approach for assessing energy intake. However, this method requires literate and highly motivated subjects. This is a particular problem for adolescents and young adults who are the least likely to undertake food records. The ready access of the majority of the population to mobile phones (with integrated camera, improved memory capacity, network connectivity and faster processing capability) has opened up new opportunities for dietary assessment. The dietary information extracted from dietary assessment provide valuable insights into the cause of diseases that greatly helps practicing dietitians and researchers to develop subsequent approaches for mounting intervention programs for prevention. In such systems, the camera in the mobile phone is used for capturing images of food consumed and these images are then processed to automatically estimate the nutritional content of the food. However, food objects are deformable objects that exhibit variations in appearance, shape, texture and color so the food classification and volume estimation in these systems suffer from lower accuracy. The improvement of the food recognition accuracy and volume estimation accuracy are challenging tasks. This thesis presents new techniques for food classification and food volume estimation. For food recognition, emphasis was given to texture features. The existing food recognition techniques assume that the food images will be viewed at similar scales and from the same viewpoints. However, this assumption fails in practical applications, because it is difficult to ensure that a user in a dietary assessment system will put his/her camera at the same scale and orientation to capture food images as that of the target food images in the database. A new scale and rotation invariant feature generation approach that applies Gabor filter banks is proposed. To obtain scale and rotation invariance, the proposed approach identifies the dominant orientation of the filtered coefficient and applies a circular shifting operation to place this value at the first scale of dominant direction. The advantages of this technique are it does not require the scale factor to be known in advance and it is scale/and rotation invariant separately and concurrently. This approach is modified to achieve improved accuracy by applying a Gaussian window along the scale dimension which reduces the impact of high and low frequencies of the filter outputs enabling better matching between the same classes. Besides automatic classification, semi automatic classification and group classification are also considered to have an idea about the improvement. To estimate the volume of a food item, a stereo pair is used to recover the structure as a 3D point cloud. A slice based volume estimation approach is proposed that converts the 3D point cloud to a series of 2D slices. The proposed approach eliminates the problem of knowing the distance between two cameras with the help of disparities and depth information from a fiducial marker. The experimental results show that the proposed approach can provide an accurate estimate of food volume