Czy białko może być obecne w glebie nawet 20 lat? Ocena zawartości ogólnych i łatwoekstrahowalnych glomalin w archiwalnych próbach glebowych

Glomaliny to glikorpoteiny grzybowe, które są wyjątkowo odporne na degradację (obecne w glebie nawet od 10 do 30 lat) oraz trudno rozpuszczalne w wodzie. Celem niniejszej pracy była ocena zawartości ogólnych i łatwoekstrahowalnych glomalin w archiwalnych próbkach glebowych. Do badań wybrano 15 próbek glebowych z doświadczeń polowych z 1994 roku dotyczących uprawy jęczmienia jarego. Badane gleby pochodziły z różnych regionów Polski oraz reprezentowały różne typy gleb. Gleby charakteryzowały się także dużym zróżnicowaniem właściwości fizykochemicznych i biologicznych. Przeprowadzone w niniejszej pracy badania wykazały obecność glomalin we wszystkich próbkach glebowych. Stężenie ogólnych i łatwoekstrahowalnych glomalin zależało głównie od typu gleby. Obecność glomalin w badanych glebach potwierdza hipotezę, iż białka te są szczególnie odporne na degradację i mogą pozostać w niezmienionej formie w glebie przez wiele lat.

Glomalines are thermostable, water-insoluble glycoproteins abundantly produced by Glomus fungi and tends to accumulate in the soil, that surrounds soil aggregates and protects them from destroying. Glomalines are especially resistant to destruction, hard to dissolve in water, while very easy dissolve in high temperature (121°C) in citrate buffer with neutral or alkali pH. These proteins have very unique physico-chemical properties performing a fundamental role in making soil structure. The content of glomalin in soil particles is significantly correlated with their stability (water resistance). It is possible that glomalin is involved in the formation of hydrophobic properties of soil, improving water and air relations in soil. Glomalines are mainly located on the surface of hyphae and spores of AM (arbuscular mycorrhizal) fungi and a hydrophobic substances covers and protects it from the degradation by other microorganisms. It also increases the stiffness and the durability of the cell of fungi facilitating their distribution in the soil. Production and distribution of glomalin in soil involves many factors, both related to the physico-chemical properties of soil and plant and fungal species. The structure of soil and its chemical properties have a significant effect on the growth of mycelium, and therefore the glomalin content. Glomalins are very resistant to degradation. As aging hyphae outside the root and the roots of plants, biomass mycelium of AMF fungi is degraded – but not glomalin. This protein is unchanged is able to survive in the soil even decades. Glomalins commonly occur in different types of soils. The aim of the study was to demonstrate the presence of total and easy extractable glomalins in archival samples of soil from the collection of soil Department of Microbiology IUNG-PIB in Puławy. The study selected 20 soil samples from field trials in 1994 with the cultivation of barley. The soil samples survey from various Polish regions and represented different types of soils. Soils were characterized by different physical, chemical and biological properties. The studies carried out in this paper have shown the contents of glomalin in all soil samples. The concentration of total and easily extracted glomalin depend mainly on the type of soil. The presence of glomalin in soils confirms the hypothesis that these proteins are particularly resistant to degradation and can remain unchanged in the soil even decades.