The food industry is constantly struggling with one of the most prevalent biofilm-forming and food-borne pathogenic bacteria, Campylobacter jejuni. Different approaches are used to control biofilms ...in the food production chain, but none is fully effective. In this study, we aim to produce and determine the chemical profile of essential oils (EOs), ethanolic extracts of flowers prior to distillation (EFs), and ethanolic extracts of post-distillation waste material (EWMs) from Lavandula × intermedia ‘Bila’, ‘Budrovka’ St Nicholas and ‘Budrovka’, which were further used to reduce C. jejuni intercellular signaling, adhesion, and biofilm formation, as well as to test their antioxidant activity. Glycosides of hydroxycinnamic acids were the major constituents of both types of lavandin ethanolic extract, while linalool, linalyl acetate, 1,8-cineol, and camphor were the major compounds found in lavandin EOs. Tested EOs showed the best antibacterial activity with a minimal inhibitory concentration of 0.25 mg/mL. Lavandin EFs proved more effective in reducing C. jejuni intercellular signaling and adhesion compared to lavandin EOs and EWMs, while lavandin EOs showed a slightly better effect against biofilm formation. Interestingly, the best antioxidant activity was determined for lavandin EWMs. A positive and moderate correlation was found between the reduction of C. jejuni intercellular signaling and adhesion, as well as between adhesion and biofilm formation. These findings mean novel bacterial targets are of interest for biofilm control with alternative natural agents throughout the whole food production chain.
The aim of the study was to investigate the essential oil (EO) of
x
cv. Bila, which has not been studied before. The EOs were distilled from plants collected in two consecutive years on the island of ...Hvar (Croatia) and in the Karst (Slovenia) and analysed for chemical composition and antimicrobial activity. The main component of EOs was linalool, but the EOs from Hvar had higher contents of Z-β-ocimene and borneol + lavandulol than the EOs from Karst, in which camphor, linalyl acetate and 1,8-cineole predominated. The antimicrobial activity was evaluated using the minimum inhibitory concentration and proved that the EOs were effective against
spp. Studies have shown that the composition of
x
EO depends on the variety and the climatic and geographical characteristics of the plant growth. The antimicrobial activity of EO is also influenced by the type and strain of microorganisms involved in the research.
The abandoned Sitarjevec mine represents a specific environment (complete darkness; 10 °C) with waters of pH 3 and it contains various ores (e.g. lead, mercury, zinc, iron, copper) and many different ...minerals (e.g. anglesite, baryte, cinnabar, pyrite, cerussite, quartz, siderite). The aim of this study was to characterize the iron oxide/hydroxide speleothems that show rapid growth of up to 5 cm/year. Their morphological and chemical characterization showed that they have a layered structure with different ferrihydrite minerals (i.e. goethite, feroxyhyte, lepidocrocite). Scanning electron microscopy-energy dispersive X-ray spectrometry confirmed that the surface layers were very porous, while for the inner parts, the bulk was compact. Bacterial populations in these speleothems and their environment were analyzed using 16S rRNA sequencing. These data revealed a great diversity of bacteria, which included 19-34 phyla across different samples. Proteobacteria were dominant in all of the samples (60-95%), although the highest bacterial diversity was seen for a water sample from the base of the speleothem, with 670 different genera and 100 different species detected. Among these there were typical iron-oxidizing bacteria, like Gallionella capsiferriformans, Sideroxydans lithotrophicus, Sphingomonas echinoides, Candidatus Nitrotoga Nitrotoga, Leptospirillum ferrooxidans, and Ferrovum myxofaciens. These iron-oxidizing bacteria were not present in other samples from the mine. Therefore, these bacteria might be involved in the structural growth of these speleothems. The specific bacterial interactions with the minerals under the environmental conditions in the mine need to be further analyzed and evaluated.
Rubies from the Prilep dolomitic marble contain numerous diaspore inclusions, resulting from oriented intergrowth with corundum. In the world of gemstones, this phenomenon has been recognized as ...diasporescence, which has to date been researched only in the cases of corundum crystals from Macedonia. The paper describes the importance of diasporescence for the appearance and thus the quality of rubies, in which the inclusions of diaspore are also a distinctive character for the determination of the origin of this renowned gemstone. Diaspore is colourless to white and affect on intensity of red to pink colour of ruby as a gem. Macedonian rubies are the only rubies from around the world with inclusions of diaspore and that´s why also the only rubies with optical phenomena diasporescence.
This lecture text presents features of the fascinating mineral corundum and its gem varieties, ruby and sapphire. The geologic occurrences of its varieties and the best-known world localities are ...presented in detail. The mineralogy and crystallography of corundum, as well as its occurrence forms, are discussed. The origin of their colour varieties and their usage are described, in addition to their important physical characteristics. Applications in the watch and laser industries and as an abrasive material, among others, are included. The ruby variety from dolomite marble in North Macedonia exhibits the unique optical phenomenon known as diasporescence–the inclusion of diaspore crystals in the corundum matrix. This phenomenon affects the parting of corundum crystals and influences their colour, density and hardness. Therefore, special attention is paid here to morphological and physical characteristics of the Macedonian gem corundum.
The Jezersko meteorite is a newly confirmed stony meteorite found in 1992 in the Karavanke mountains, Slovenia. The meteorite is moderately weathered (W2), indicating short terrestrial residence ...time. Chondrules in partially recrystallized matrix are clearly discernible but often fragmented and have mean diameter of 0.73 mm. The meteorite consists of homogeneous olivine (Fa19.4) and low‐Ca pyroxenes (Fs16.7Wo1.2), of which 34% are monoclinic, and minor plagioclase (Ab83An11Or6) and Ca‐pyroxene (Fs6Wo45.8). Troilite, kamacite, zoned taenite, tetrataenite, chromite, and metallic copper comprise about 16.5 vol% of the meteorite. Phosphates are represented by merrillite and minor chlorapatite. Undulatory extinction in some olivine grains and other shock indicators suggests weak shock metamorphism between stages S2 and S3. The bulk chemical composition generally corresponds to the mean H chondrite composition. Low siderophile element contents indicate the oxidized character of the Jezersko parent body. The temperatures recorded by two‐pyroxene, olivine‐chromite, and olivine‐orthopyroxene geothermometers are 854 °C, 737–787 °C, and 750 °C, respectively. Mg concentration profiles across orthopyroxenes and clinopyroxenes indicate relatively fast cooling at temperatures above 700 °C. A low cooling rate of 10 °C Myr−1 was obtained from metallographic data. Considering physical, chemical, and mineralogical properties, meteorite Jezersko was classified as an H4 S2(3) ordinary chondrite.
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