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  • Author: Marta Siebyła x
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Abstract

This paper describes the quantitative and qualitative composition of bacteria isolated from soil in the selected sites in the Nida Basin, in places where mycorrhizae and ascocarps of summer truffle (Tuber aestivum) were found, and in a control soil (without truffle). A classic growth culture method was used with Sanger DNA sequencing to obtain quantitative and qualitative measures of bacterial cultures. The obtained results showed differences in bacteriome composition between the case samples, in which summer truffle fructification was observed, and the control samples. Seven classes of bacteria were identified: Actinobacteria, Bacilli, Deinococci, Flavobacteria, Alphaproteobacteria, Betaproteobacteria, and Gammaproteobacteria. The most numerous bacterial genera were Pseudomonas (class Gammaproteobacteria) – 33%, Streptomyces (class Actinobacteria) – 29% and Bacillus (class Bacilli) – 15%. This research broadens the understanding of individual groups of bacteria accompanying truffles and their potential impact on the formation of summer truffle ascocarps.

Abstract

This study is designed to test the potential for reducing the growth of the mycelium of the fungus Hymenoscyphus fraxineus (anamorph Chalara fraxinea) by using phosphite preparations at various concentrations in vitro. The study shows that adding pure phosphite to potato dextrose agar media inhibits the development of the fungus, but if the preparation is applied in the form of ammonium phosphite (Actifos), the growth of fungus will be accelerated. Probably the addition of nitrogen contained in the product Actifos has positive effect on the mycelial growth, but pure phosphite restricts its development. These studies are preliminary and only show the potential use of phosphite to reduce the development of H. fraxineus; however, to completely confirm its operation, further research is needed in this area.

Abstract

Slow Sand Filters (SSF) are a biological method used to protect nursery plants, from pathogen infections which can cause serious diseases in many forest tree species. Thanks to SSF application the number of phytopathogens in nurseries can be significantly reduced, as demonstrated by many field and greenhouse experiments (e.g. in Polish nurseries, and for horticultural crops in Germany and The Netherlands).

In this study, the effect of pollution from fertilizers and fungicides used in agriculture (e.g. PCNB) on the efficiency of SSFs was assessed. A quantitative analysis was performed of the copiotrophic and oligotrophic bacterial composition colonizing SSF biofilms. The efficiency with which selected Oomycete strains belonging to the genus Phytophthora (P. alni, P. cactorum, P. plurivora) were removed from water was determined based on genetic material (DNA of the organisms) found in the SSF filtrate. Specific primers and TaqMan probes (qPCR) appeared to be the most sensitive molecular methods. Moreover, the microbiological analysis of SSF biofilm performed with selective media allowed the growth of copiothrophic and oligothrophic bacteria to be estimated. The influence of fungicide (PCNB) and N-fertilizer on the number of bacteria in each biofilm was also evaluated.

The pollution of water with fertilizer (being used for plant irrigation) was demonstrated to reduce the efficiency of filtration more than fungicide addition (the amount of DNA from those investigated pathogens in the water decreased with time). The amount of bacteria in SSF biofilm readily increased after application of N-fertilizer in contrast to fungicide (PCNB) addition.