Antimicrobial Activity of Selected Essential Oils on Pseudomonas Species Associated with Spoilage of Fish with Emphasis on Cinnamon Essential Oil

ABSTRACT

Eight plant essential oils (cardamom, cinnamon, clove, eucalyptus, lemongrass, lime, nutmeg and rosemary) were evaluated for their antimicrobial activity against three Pseudomonas species associated with microbial spoilage of refrigerated tilapia. In vitro test of the essential oils, using disc-diffusion method, showed various degrees of antimicrobial activity against the Pseudomonas species. Cinnamon essential oil (CEO) had the highest antimicrobial activity, followed by clove essential oil. The remaining essential oils showed consistently weak activity. The antimicrobial efficiency of CEO against the Pseudomonas species was confirmed by potential minimum inhibitory concentration and minimum bactericidal concentration values, ranging between 0.125 and 0.375 µL/mL and 0.250–0.500 µL/mL, respectively. The anti-Pseudomonas activity of CEO was also tested in fish extract model at refrigeration temperature. The essential oil reduced the Pseudomonas viable count in fish extract but to a lesser extent than when it was applied at the same concentrations in culture medium. The chemical composition of CEO showed that the oil contained 79.1% cinnamaldehyde, which was suggested to be responsible for its antimicrobial activity. These results revealed the potential of CEO as a promising natural antimicrobial agent that could efficiently contribute to the control of spoilage bacteria and retard microbial spoilage of fresh fish.     

Evidence for extreme climatic warmth from late cretaceous arctic vertebrates

A Late Cretaceous (92 to 86 million years ago) vertebrate assemblage from the high Canadian Arctic (Axel Heiberg Island) implies that polar climates were warm (mean annual temperature exceeding 14 degreesC) rather than near freezing. The assemblage includes large (2.4 meters long) champsosaurs, which are extinct crocodilelike reptiles. Magmatism at six large igneous provinces at this time suggests that volcanic carbon dioxide emissions helped cause the global warmth.     

Identification of Wap65, a human homologue of hemopexin as a copper-inducible gene in swordtail fish, <Emphasis Type="Italic">Xiphophorus helleri</Emphasis>

Copper is one of the major heavy metal pollutants found in the aquatic environment. Therefore, it is important for determining the genes that play a key role in copper metabolism in aquatic organisms. This study, thus, aimed to identify a new copper-inducible gene in swordtail fish, Xiphophorus helleri. Using ACP-based RT-PCR coupled with RLM-RACE, we cloned Wap65, a mammalian homologue of hemopexin gene. The gene exhibits high identity at amino acid levels with the Wap65 gene of other fish species (42–68%) and mammalian hemopexin gene (35–37%). In addition, ten cysteine and two histidine residues are conserved in the swordtail fish Wap65 gene. These cysteine residues are vital for structural integrity, and histidine residues provide high binding affinity towards heme. As revealed by RT-PCR, the gene was upregulated in swordtail fish that were exposed to copper in a dose- and time-dependent manner. Therefore, the identification of Wap65, a mammalian homologue of hemopexin, as a new copper-inducible gene will provide greater insight into the role of this gene in copper metabolism.     

Effect ofZinnia elegans as a mix-crop along with tomato againstMeloidogyne incognita andRotylenchulus reniformis

Effect of nematicidal potential ofZinnia elegans Jacq (1, 2, 3 & 4 plants per pot) as a mix-crop along with tomato againstMeloidogyne incognita andRotylenchulus reniformis was studied under a greenhouse conditions. The nematode final population of both nematodes and their rate of build up as well as the root gall index were significantly affected by the number of zinnia plants when grown with tomato together. There was a negative correlation between the number of zinnia seedlings and the final population of both nematodes. The lowest nematode final population and rate of build up were determined at the highest number of zinnia plants (4 plants per pot). The highest number of root gall index was found on roots of tomato grown alone (4), while, the lowest one was found on roots of tomato (0.7) grown with four plants of zinnia. This type of control is considered inexpensive and pollution-free.

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Zusammenfassung Zur Wirkung vonZinnia-Pflanzen in Mischung mit Tomate gegen die NematodenMeloidogyne incognita undRotylenchulus reniformis.Bei Zugabe von 1, 2, 3 oder 4 Pflanzen vonZinnia elegans pro Topf zu Tomate unter Gewächshausbedingungen wurden die Enddichte der Wurzel-NematodenMeloidogyne incognita undRotylenchulus reniformis sowie die Reproduktionsrate und der Wurzelgallenindex signifikant beeinflußt, und zwar mit steigender Zahl an Zinnia-Pflanzen vermindert. Der höchste Wurzelgallen-Index (4,0) wurde bei allein wachsender Tomate pro Topf festgestellt, der niedrigste Index (0,7) bei Anwesenheit von 4 Zinnien. Diese Form der Wurzelnematodenbekämpfung ist billig und frei von Umweltbelastungen.

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With 2 tables     

Effect of some oilseed cakes as soil amendments and Aldicarb on cowpea plants infected with Rotylenchulus reniformis Lin. & Ol. in relation to soil type

Cotton, linseed, soybean and sunflower oilseed cakes as well as aldicarb were used to study their effect on the reproduction of R. reniformis and growth of cowpea plants under greenhouse conditions. All treatments of oilseed cakes and aldicarb reduced final population, rate of build up and reproduction of nematode than those of untreated soil in all soil types. The reduction in such values varied greatly according to the type of employed oilseed cakes and soil type. In general, cotton and sunflower proved to be the most effective oilseed cakes for controlling. R. reniformis and gave the greatest growth of cowpea plants when, compared with the other tested oilseed cakes in sandy and both sandy loam and clayloam soil, respectively. Aldicarb was superior and very potent inhibitor to the reniform nematode reproduction, when compared to the tested oilseed cakes in all soil types.     

Antimicrobial screening of plants used for traditional medicine in the state of Perak, Peninsular Malaysia

Seventy-two extracts (methanol) obtained from the leaves, barks, and roots of 50 plant species used in the traditional medicine of Perak, Peninsular Malaysia, have been screened for antibacterial and antifungal activities. Peristrophe tinctoria, Polyalthia lateriflora, Knema malayana, Solanum torvum, Celosia argentea, Eclipta prostrata, Ancistrocladus tectorius, Dillenia suffruticosa, Piper stylosum and Rafflesia hasseltii displayed the broadest spectrum of activity.     

Effects of root diffusates of some weeds associated with corn plantations on the hatchability of the corn cyst nematode,Heterodera zeae

Twenty two summer weeds belonging to fifteen plant families and twelve winter weeds from eight plant families were tested to compare the effects of their root diffusates with the corn root diffusates (CRD) of cv. Giza 2 on the hatchability of the corn cyst nematode (CCN),Heterodera zeae.All tested weed root diffusates (WRD) successfully stimulated the hatchability of the cysts, but less than CRD did except the root diffusates (RD) ofRumex dentatus which failed to stimulate the nematode cysts.As for the summer weeds, RD ofEchinochloa colonum was the most effective treatment, followed byChenopodium album, Malva parviflora andPortulaca oleracea. While, RD ofBeta vulgaris, Convolvulus arvensis andSolanum nigrum had the lowest effect.As to the winter weeds, RD ofMelilotus indica was the most effective treatment followed byLolium multiflorum andBrassica kaber; whereas, RD ofRumex dentatus failed to stimulate the hatchability of the nematode cysts.     

Effect of Drought Conditions at Boiling Stage on Some Chemical Constituents of Cotton Plant

The investigation was carried out to study the effect of drought conditions at boiling stage on chloroplast pigments and anthocyanin, in leaves, carbohydrate, phenols and total amino nitrogen content in leaves and roots, oil and protein contents in bolls of different ages. Seeds of cv. Giza 75 cotton were sown during 1987 and 1988 seasons in pots of 30 cm in diameter containing 11 kg of soil; after complete germination, thinning was carried out leaving one plant per pot. Plants were subjected to water stress conditions at boiling stage till the sign of wilting, while the control plants were irrigated regularly at this stage without allowing the plants to reach wilting stage and kept in turgid state. The results obtained can be summarized as follows:
1. Drought conditions decreased reducing sugar, nonreducing sugar, total soluble sugar and total amino nitrogen in leaves, while the reverse was true in roots.
2. Drought conditions reduced total and polyphenols content in leaves while it had no effect on phenols compounds in roots.
3. Drought conditions had no significant effect on pigments except total carotenoid in 1987 season.
4. Oil content in seeds of different boll ages decreased as a result of drought in both seasons.
5. In general drought condition increased protein content in 1987 season while the reverse was true in 1988 season.
6. Leaves and roots of wilted plants had more inhibitors as compared to turgid plants.