Anna Maráz

Phylogeny and systematics of the fungi with special reference to the Ascomycota and Basidiomycota.

In 1965, Zuckerkandl and Pauling [1] argued that sequence comparison of informational macromolecules permits the evaluation of evolutionary relatedness, thereby fomenting a phylogenetic revolution, especially in prokaryotic organisms and protists [2, 3]. Protista were once considered as a distinct third kingdom besides animals and plants by Haeckel [4]. Kimura’s neutral theory of molecular evolution also had an impact on studies of the phylogeny and evolution, especially of microorganisms with an inadequate fossil record [5–7]. Meanwhile, molecular systematics has revolutionized our understanding of the microbial world. Currently, phylogenies of the Eukarya depend principally on small [3, 8, 9–17] or large [18–24] ribosomal RNA (rRNA) subunits, although 5S rRNA [25, 26] and a number of protein sequences [27, 28] also influence phylogenetic interpretations. Based on 18S rDNA sequencing, the Ascomycota and Basidiomycota form monophyletic clades within the kingdom Mycobionta or chitinous Fungi (fig. 1) [14, 29–31]. Defined by a membrane-bounded nucleus, the kingdom Mycobionta is one of several kingdoms within the crown groups of the Eukarya or eukaryotes (fig. 1).

Food Spoilage by Cold-Adapted Yeasts

This Chapter gives an overview of the spoiling potential of cold-adapted yeasts under different food ecological conditions. Special attention is paid to the physiological characterisation of the most important food-spoilage yeasts, illustrating the elevated tolerance of cold-adapted spoilage yeasts to one or more food-related stress factors. Finally, spoilage yeast associations and food deterioration problems caused by cold-adapted spoilage yeasts in different type of foods (fruits, vegetables, beverages, dairy and meat products) are introduced in details.

Élelmiszer-biztonsági jelentőségű baktériumok molekuláris detektálásának fejlesztése miniatürizált mikrofluidikai eszközök segítségével

Absztrakt A biztonsagos elelmiszerek előallitasa szempontjabol kulcsfontossagu az elelmiszerrel terjedő patogen bakteriumok kimutatasa es azonositasa. A hagyomanyos, tenyesztesen alapulo diagnosztikai eljarasokat egyre inkabb felvaltjak vagy kiegeszitik a nukleinsav-alapu, a genom specialis (elsősorban virulencia) genjeinek kimutatasat celzo molekularis technikak. A rutin elelmiszer-mikrobiologiai vizsgalo laboratoriumok leggyakrabban nemzetkozileg validalt DNS-amplifikacios, elsősorban valos idejű polimeraz lancreakcio alapu modszereket alkalmaznak, amelyek a vizsgalati idő jelentős leroviditese mellett lenyegesen javitjak a modszerek teljesitesi jellemzőit (peldaul erzekenyseg, specifikussag) is. A polimeraz lancreakcio alapu modszereknek rutindiagnosztikai celu alkalmazasa azonban az előnyok mellett szamos hatrannyal is jar, amelyek kozott emlitendő a keszulekek es a reagensek magas koltsege, valamint a laboratoriumi kornyezetnek a reakciotermekekkel valo kontaminalasi kockazata, ami elkulonitett laboratoriumi rendszert igenyel. Manapsag az ilyen laboratoriumi rendszerek miniaturizalasa es hordozhatova tetele is fontos fejlesztesi irany. A Lab-on-a-chip eszkozokben tobb ilyen laboratoriumi műveletet lehet megvalositani egy kis meretű eszkozon, a standard eljarasokhoz hasonlo pontossaggal es megbizhatosaggal. Ezen miniaturizalt eszkozok nagy előnye az egyszerű – sokszor automatizalt – kezelhetőseg, kis meret, hordozhatosag es sterilitas, ami az egyszeri hasznalatbol adodik. Ilyen miniaturizalt gyorsdiagnosztikai eszkozok kutatasa es fejlesztese folyik a vilag vezető kutatohelyein, peldaul kulonboző minta-előkeszitesi es DNS-amplifikacios modszerek miniaturizalasaval. A szerzők is ezt a celt tűztek ki kutatasaikban: olyan miniaturizalt mikrofluidikai eszkozok fejleszteset, amelyek alkalmasak elelmiszer-biztonsagi jelentősegű bakteriumok molekularis detektalasara. Orv. Hetil., 2015, 156(51), 2082–2088.

Colonization ability of escherichia coli and listeria monocytogenes in the endosphere of sweet pepper (Capsicum annuum Var. grossum)

Fruits and vegetables can be transmission vehicles of human opportunistic and obligate pathogenic bacteria, persisting in inner tissues for shorter or longer periods or colonizing the plants as facultative endophytes. In this study we investigated the ability of commensal E. coli and pathogenic L. monocytogenes strains to internalize sweet pepper seedlings via seed bacterization, as germinating seeds and roots are important infiltration sites for entry of enteric bacteria. By combining cultivation dependent and independent (PCR and FISH-CLSM) techniques we could not detect stably or transiently colonized inoculated bacteria in 6–7 weeks old pepper seedlings, suggesting that there is low risk associated with internalized enteric or human pathogenic bacteria via germinating seeds in sweet pepper.

Purification and Characterization of a Novel Cold-Active Lipase from the Yeast Candida zeylanoides.

Cold-active lipases have attracted attention in recent years due to their potential applications in reactions requiring lower temperatures. Both bacterial and fungal lipases have been investigated, each having distinct advantages for particular applications. Among yeasts, cold-active lipases from the genera Candida, Yarrowia, Rhodotorula, and Pichia have been reported. In this paper, biosynthesis and properties of a novel cold-active lipase from Candida zeylanoides isolated from refrigerated poultry meat are described. Heat-sterilized olive oil was found to be the best lipase biosynthesis inducer, while nonionic detergents were not effective. The enzyme was purified to homogeneity using hydrophobic chromatography and its enzymatic properties were tested. Pure enzyme activity at 7°C was about 60% of the maximal activity at 27°C. The enzyme had rather good activity at higher temperatures, as well. Optimal pH of pure lipase was between 7.3 and 8.2, while the enzyme from the crude extract had an optimum pH of about 9.0. The enzyme was sensitive to high ionic strength and lost most of its activity at high salt concentrations. Due to the described properties, cold-active C. zeylanoides lipase has comparative advantages to most similar enzymes with technological applications and may have potential to become an industrially important enzyme.

Antagonističko djelovanje bakterije Pseudomonas sp. CMI-1 na patogenu bakteriju Listeria monocytogenes u hrani

In this study, the influence of lactic acid fermentation on the quality of tomato powder was evaluated. The effect of adding fermented tomato powder to ready-to-cook minced pork meat to improve its nutritional value and sensory characteristics was also analysed. The cell growth of Lactobacillus sakei (7.53 log CFU/g) was more intense in the medium containing tomato powder, compared to the growth of Pediococcus pentosaceus (6.35 log CFU/g) during 24 h of fermentation; however, higher acidity (pH=4.1) was observed in the tomato powder samples fermented with Pediococcus pentosaceus. The spontaneous fermentation of tomato powder reduced cell growth by 38% and pH values slightly increased to 4.17, compared to the fermentation with pure LAB. The lactofermentation of tomato powder increased the average β-carotene and lycopene mass fractions by 43.9 and 50.2%, respectively, compared with the nonfermented samples. Lycopene and β-carotene contents in the ready-to-cook minced pork meat were proportional to the added tomato powder (10 and 30%). After cooking, β-carotene and lycopene contents decreased, on average, by 24.2 and 41.2%, respectively. The highest loss (up to 49.2%) of carotenoids was found in samples with 30% nonfermented tomato powder. Tomato powder fermented with 10% Lactobacillus sakei KTU05-6 can be recommended as both a colouring agent and a source of lycopene in the preparation of ready-to-cook minced pork meat.Chokeberries (Aronia melanocarpa) are rarely used in diet in Croatia but they have high content of polyphenolic compounds and one of the highest in vitro antioxidant activities among fruits. The aim of this study is to compare the quality, phenolic content and antioxidant capacity of different chokeberry products (juices, powders, fruit tea, capsules and dried berries). It can be expected that processing influences antioxidant activity and phenolic content of final products reaching consumers. Characterisation of phenolic compounds was carried out by using spectroscopic methods (Folin-Ciocalteu and pH differential methods). Antioxidant activity of chokeberry products was determined using 2,2-diphenyl-2-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) methods. The results show that the investigated products contain high amount of phenols (3002 to 6639 mg per L and 1494 to 5292 mg per 100 g of dry matter) and lower amount of total anthocyanins (150 to 1228 mg per L and 141 to 2468 mg per 100 g of dry matter). The examined juices and other chokeberry products possess high antioxidant capacity (12.09 to 40.19 mmol per L or 58.49 to 191.31 mmol per 100 g of dry matter, respectively) and reducing power (38.71 to 79.86 mmol per L or 13.50 to 68.60 mmol per 100 g of dry matter, respectively). On the basis of phenolic content and antioxidant activity, capsules and powders stand out among other products. The study indicates that there are significant differences (p<0.05) in the quality, phenolic content and antioxidant capacity among examined products.