Pseudomonas aeruginosa is a globally distributed environmental bacterium, which is also a significant opportunistic pathogen of humans, animals and plants. It is considered that wide distribution of this bacterium is connected with its most significant constitutive property to form biofilms, and that this multicellular mode of growth, predominant in nature, serves as a protective mechanism against unfavourable environmental conditions. The work presented here examines the phenotypic diversity of Pseudomonas aeruginosa environmental isolates with respect to biofilm production capacity under different environmental conditions (temperature, pH, NaCl), production of virulence factors, and motility. The purpose of this work is to present the production of two quorum sensing-regulated virulence factors (rhamnolipids and pyocyanin), explore different motility tests (swimming, swarming and twitching) and discover potential relationship between assessed phenotypic features. Obtained results delineate environmental conditions coinciding with biofilm production and suggest a high correlation between rhamnolipid production levels and biofilm formation. Rhamnolipids affect motility competence, yet only the flagellum-mediated swimming motility has significant impact on the biofilm formation potential. Although it is challenging to demarcate a definitive, clear correlation between parameters tested, rhamnolipid content appears to serve as a link between the tested phenotypic factors.

This paper deals with the consequences of cultural eutrophication and unconventional solutions for shallow lake restoration. Cultural eutrophication is the primary problem that affects especially shallow lakes, due to their physical characteristics (e.g. shallow depth, lack of stratification). Palic Lake, a very shallow Pannonian lake, received treated municipal wastewaters coming from the lagoons of a wastewater treatment plant. The sewage discharge mainly increased the nutrient load to the lake in the last decades. The lake sustainability is affected by inappropriate quality of water that flows into the lake, and abundance of deposited sediment. The technology that can provide both improvement of water quality and resolution of the sediment problem is a constructed wetland, which is designed to utilise the natural processes involving wetland vegetation, soil and their associated microbial assemblages to assist in additional water treatment. The technical solution is based on three key aspects: quality and quantity of deposited sediment, enriched by nutrients; effluent quality; desired lake water quality. A designed constructed wetland can accomplish the desired water quality and gradually remediate deposited sediment.

Palic and Ludas lakes are shallow Pannonian lakes, which have undergone rapid eutrophication. High concentrations of nutrients, along with significantly high values of fecal indicators in water samples, indicate that the Palic-Ludas canal, which connects them, contributes to the pollution of the recipient Lake Ludas, a central part of a special nature reserve. In order to improve water quality in the canal and decrease nutrient load of Lake Ludas, it is suggested to use environmentally friendly solutions, so-called bio-barriers (bio-bridges and biobanks), which will contribute to self-purification efficiency. The given model assumes 10 zones with bio-bridges and 0.4 ha covered by biobanks, using plants common in the area, e.g. Typha spp., Phragmites spp., Juncus spp., Scirpus spp. and Carex spp. The main disadvantage of this technology is occupation of large area; thus, the solution seems to be undersized. It removes 4% TN/year and 8% TP/year of the total amount necessary to achieve good ecological status. Nevertheless, the role of bio-bridges in permanent nutrient removal, through preventing the deposition of organic matter at the bottom sediment and later return of nutrients in water, together with indirect influence through enhancement of biodiversity should not be underestimated.

No abstract

Lake Palic is a typical, shallow Pannonian plain lake, with thick sediment layers and high content of phosphorus and nitrogen. The thick layers are the result of accelerated eutrophication, and cause biodiversity loss and disruption of the ecosystem. Numerous methods can be used to overcome the problem of accelerated eutrophication, (sediment removal, phosphorus inactivation etc.). However, these methods have many deficiencies. Lately, using macrophytes as a way to resolve this problem is becoming more and more popular. The aim of this work was to examine the germination possibilities of white mustard (Sinapis alba L.), alfalfa (Medicago sativa L.), oats (Avena sativa L.) and lettuce (Lactuca sativa L.) on Lake Palic?s sediment, as a prescreening test for their suitability for further phytoremediation. The results show that plant species can germinate and grow in early stages in such substrates, so they can be recommended for sediment phytoremediation. [Projekat Ministarstva nauke Republike Srbije, br. TR 31080]