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Abstract

In this study molecular microbiological and multivariate statistical analyses were carried out to determine the structure and dynamics of bacterial communities through a biofilm based, pilot-scale wastewater treatment cascade system comprised of eight reactors. Results indicated a vertical as well as horizontal differentiation of biofilm bacterial communities within individual reactors and through the reactor series, respectively. The richness of biofilm samples taken from dissolved oxygen rich sections of reactors were relatively lower than of samples taken from less oxygenized sections (one-way ANOVA P = 0.07). The Euclidean distance based one-way ANOSIM pointed out that in bacteriological point of view: (1) no statistically significant difference could be observed among the first five reactors (P ≥ 0.1); (2) the first seven reactors differed significantly from the last reactor, (P ≤ 0.03); (3) reactors 1 and 2 differed significantly from reactors 6 and 7 (P ≈ 0.02) and (4) reactor 3 from reactor 7 (P ≈ 0.03). 16S rRNA gene cloning revealed that through the cascade system the initially dominant heterotrophic bacteria (Acinetobacter, Acidovorax, Parabacteroides, Thauera, Desulfobacterium and Desulfomicrobium) were gradually replaced or supplemented by autotrophic nitrifying bacteria (Nitrosomonas, 'Candidatus Nitrotoga' and Nitrospira). Our results indicate that the vertical alteration of bacterial community structure within a particular reactor was driven by the alteration of dissolved oxygen concentration, while the horizontal alteration of bacterial community structure through the cascade system was driven mainly by the gradually decreasing dissolved organic matter content and increasing dissolved oxygen concentration.

Due to the climate change, aflatoxigenic Aspergillus species and strains have appeared in several European countries, contaminating different agricultural commodities with aflatoxin. Our aim was to screen the presence of aflatoxigenic fungi in maize fields throughout the seven geographic regions of Hungary. Fungi belonging to Aspergillus section Flavi were isolated in the ratio of 26.9% and 42.3% from soil and maize samples in 2013, and these ratios decreased to 16.1% and 34.7% in 2014. Based on morphological characteristics and the sequence analysis of the partial calmodulin gene, all isolates proved to be Aspergillus flavus, except four strains, which were identified as Aspergillus parasiticus. About half of the A. flavus strains and all the A. parasiticus strains were able to synthesize aflatoxins. Aflatoxigenic Aspergillus strains were isolated from all the seven regions of Hungary. A. parasiticus strains were found in the soil of the regions Southern Great Plain and Southern Transdanubia and in a maize sample of the region Western Transdanubia. In spite of the fact that aflatoxins have rarely been detected in feeds and foods in Hungary, aflatoxigenic A. flavus and A. parasiticus strains are present in the maize culture throughout Hungary posing a potential threat to food safety.

Vizsgálatainkat a Szent István Egyetemhez tartozó Babatvölgyi Biokertészet Tanüzem által a rendelkezésünkre bocsátott 1,4 ha területű táblán végeztük, amelynek felében alakor, felében tönke került elvetésre. Ezen belül hat eltérő tápanyagadottságú parcella került kijelölésre, amelyekben növényszám, növénymagasság, kalászhossz, bokrosodás és gyomborítottság mérését végeztük el. Az aratást követően szintén ezen parcellákra felosztva terméstömeg, szem-szalma arány és ezermagtömeg vizsgálatát is elvégeztük. Az eredményeken SPSS programmal lineáris regresszió segítségével megvizsgáltuk, hogy milyen összefüggés lehet a növény tulajdonságai és a tápanyagok mennyisége között.

Commercial polypropylene (PP), high-, medium-and low density polyethylene (HDPE, MDPE, LDPE) films, as well as MDPE films containing pro-oxidative additives and thermoplastic starch (TPS) were composted for six weeks together with biologically degradable films, such as poly (lactic acid) (PLA), Ecovio (BASF), Mater Bi(Novamont) and cellophane. Visual appearance of the polyolefin-based films did not change significantly, while the biologically degradable films fell apart. Thickness and mechanical properties of the polyolefin-based films also did not vary significantly after composting. The thickness of the degradable films however increased due to biofilm formation and finally decreased due to biodegradation, and their mechanical properties drastically dropped. FTIR proved the formation of carbonyl absorption of commercial and of the additive-containing films respectively) after composting due to oxidation. The FTIR-spectrum of the biodegradable films showed drastic change after composting. Formation of free radicals was detectable by ESR-spectroscopy, if pro-oxidative additive containing MDPE film was exposed for one week to sunlight, and the intensity of free radical formation increased after composting. The number-average molecular mass of MDPE films containing pro-oxidative additives decreased, low molecular mass fractions appeared and polydispersity increased after composting. Commercial polyolefin films were covered by microorganisms much more densly than films containing pro-oxidative additives detected by SEM. Even TPS did not increase the quantity of microorganisms. Biodegradable films were densly covered by microorganisms of different types and they became porous and holes were observable on their surface. It can be concluded that composting had no significant effect on the behaviour of the commercial PP and PE films. Signs of initial degradation were observable on MDPE films with pro-oxidative additives and TPS after 6 weeks composting, although it cannot be considered as biological degradation. Non of the tested polyolefin films suffered such degree of degradation in compost, as the biologically degradable films. It may be concluded that polyolefin films neither degrade in compost nor they undergo biodegradation.

A „Szentendrei Ökosziget – Fenntartható életmódra ösztönző komplex térségfejlesztési mintaprogram” című VM-VKSZI megállapodás keretében 2012 tavaszán elkészült a Szentendrei-sziget „Öko-sziget” Stratégiája, mely projektszinten nevesítette az Önkormányzat által, üzemeltetett kertészet kialakítása feladatot. Ennek lehatárolását és részletes kidolgozását végeztük el Szigetmonostor településen. A megvalósíthatósági terv tartalmazza a terület kiválasztását, a közkonyha igényeinek felmérését, a kertészet főbb terveit üzemeltetési, gazdasági számításokkal, valamint a tartósításhoz szükséges beruházási igényeket. A terv készítése során a környezetgazdálkodás és az ökológiai gazdálkodás szempontjaira, az egészséges élelmiszer előállításra és a vízbázis védelmére különösen nagy hangsúlyt fektettünk.