Evidence for the Presence of Hyphae and Fruiting Body Calcium Oxalate Crystallites in Schizophyllum commune

Biomineralization is a phenomenon in which organisms form crystals. Studies have shown that many fungi have the ability to biomineralize, it can exhibit calcium oxalate crystals on their hyphae and fruiting body. Schizophyllum commune is a common saprophytic fungus distributed all over the world, but there is little research on its biomineralization. In this paper, S. commune fruiting body from three different provinces of China were collected, and isolation for hyphal cultured to obtain several samples. Utilizing light microscope, FE-SEM, and EDAX, the existence of crystals on the fruiting body and mycelium of each strain was found, and their morphological characteristics and ion content were analyzed. It was ultimately established that biomineralization occurs on S. commune.


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Biomineralization refers to the process by which organisms form minerals. A wide 30 array of biologically induced minerals can be crystallized, a few others might formed 31 amorphous structure, and calcium carbonate minerals are the most abundant biogenic 32 minerals [1]. Among them calcium oxalate(CaO X ), which is formed when the product 33 of the concentrations of oxalate and calcium ions is greater than the solubility product  Many fungi have ability to exhibit CaO X crystals on their hyphae and fruiting body. 38 The ubiquity of CaO X crystals on fungal hyphae suggests that their formation may 39 provide a selective advantage to the organism [5]. In plant, Various functions have been ascribed to CaO X crystals and these diverse functions depend on crystal amount, 41 distribution, and morphology as well as features of the cells that produce them [3]. For 42 fungi, the function of calcium oxalate has yet to be established, but by speculating on 43 the function of calcium oxalate in plant, CaO X formation is hypothesized to regulate 44 intra-cellular pH and levels of oxalate and Ca and, hence, serves as a major sink for 45 toxic amounts of Ca in soil and other environments [6]. 46 Cystidia are specialized sterile cells found in the Agaricomycetes, Basidiomycota [7]. 47 Cystidia have been thought to function as space makes in the hymenium, as storage 48 cells, and its distribution throughout the various tissues, including the gills or hymenial 49 tissue [8]. Many mushrooms produce hymenial cystidia with apical crystals [9]. But how 50 the crystal formation and the crystal function on cystidia were rarely been illuminated.

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Schizophyllum commune is a species of fungus in the genus Schizophyllum. which is 52 also called split gill mushroom and "white ginseng" by local people in Yunnan province 53 of China[10], The mushroom resembles undulating waves of tightly packed 54 corals.''Gillies" or Split Gills vary from creamy yellow to pale white in color. The cap 55 is small, 1-4.5 cm wide with a dense yet spongey body texture. It is one of the most 56 common fungi, widely distributed in temperate and tropical regions, and commonly 57 occurs as a weak parasite or saprophyte on a wide range of woody plants and 58 occasionally on herbaceous plants [11]. S. commune mainly adopts a saprobic lifestyle 59 by causing white rot [12]. At least 150 genera of woody plants are substrates for S. 60 commune, but it also colonizes softwood and grass silage. The mushrooms of S. commune that form on these substrates are used as a food source in Africa and Asia [13].

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So many researches, including genetics, genome, pharmacology and also cytology, 63 have been carried out look for instance of the genetics of S. commune, which reported 64 by John Raper[14]. However, there is no report on the biomineralization of this model 65 fungus.

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In order to better understand the structural characteristics of this model organism, we  The mycelia of the tested strains of S. commune were grown in liquid CYM medium at 93 25℃ for 7 Days. Genomic DNA was extracted from mycelium frozen in liquid nitrogen 94 following CTAB method [15]. DNA concentration and purity were determined with the 95 UV-1700 spectrophotometer (Shimadzu, Japan). Qualified samples were diluted to 50 96 ng/μl for PCR amplification. Two oligonucleotide fungal primers described by   2-4μm, and the diameter of the sphere is 2.5μm (Fig. 2). showed that the tested strain was a S. commune strain.
Observation and analysis of mycelium cultured from a petri dish by optical microscope.

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There are a large number of clustered substances on the mycelium that are 165 approximately strips, prisms, or cuboids. The DIC differential imaging shows that they 166 have special light-shielding, it was observed to be transparent with transmitted light. can be 10um long and 7um wide, and some mycelium can be observed to penetrate 172 through the middle of the crystal (Fig. 2). than that in the control area(in the hyphae or in the glass slide), the C ion content is 194 11.95% and 7.35%, and the O ion content is 43.95 and 32.82%, Ca ion content is 28.82% 195 and 8.84% (Fig. 4). was significantly higher than the 13.90% percentage of control (Fig 5).  (Table 1) 233