Isolation of Polysaccharides and Terpenoids from Some Basidiomycota and Their Antibacterial Activities.

Aims: Antibacterial chemicals were isolated from fruit bodies of three basidiomycota [Coltricia perennis (L) Murrill, Onnia tomentosa (Fr.) P. Karst., and Polyporus mori (Pollini) Fr. ] fungi and their antibacterial potential were screened against five bacteria. Study Design: All experiments were performed thrice in completely randomized design (CRD) each, with five replications per treatment (antibacterial activity). The data was subjected to ANOVA. Means of three observations were compared with Duncan’s Multiple Range Test (DMRT). Place and Duration of Study: Molecular Mycopathology Laboratory, Department of Botany, Ramakrishna Mission Vivekananda Centenary College, Rahara, Kolkata, between January 2012 and February 2013. Methodology: During the rainy season in the year of 2012, a survey for mushroom collection in the forest beds, infected logs in the plain of west Bengal was conducted .The fruit bodies of some basidiomycota were collected in sterile biodegradable polythene begs and brought to laboratory. The morphology, anatomy of fruit bodies and measurement of reproductive organs were recorded. The spore prints of all collected basidiocarps were taken.The collected basidiomycota were identified. The polysaccharides from the basidiocarps of the test fungi were isolated employing the methods of Mizuno et al. [17] and Wang et al.[12].Terpeniods were isolated according to the method followed by Anke and Werte [24] and Chairul et al. [25]. Their antibacteral activities were assayed against five bacteria [three Gram positive bacteria (Staphylococcus aureus, Micrococcus roseus and Bacillus brevis ) and two Gram negative bacteria (Ralstonia solanacearum and Escherichia coli )] following the agar plates cup diffusion techniques. Results: Terpenoid isolated from Coltricia perennis was most active in inhibiting the growth of all five bacteria. This terpenoid inhibited maximum (25 ±2.4mm) growth against Staphylococcus aureus and minimum against Micrococcus roseus (17±1.1mm). The polysaccharides isolated from these three mushrooms were less active against the test five bacteria. The terpenoids isolated from Onnia tomentosa and Polyporus mori also inhibited the growth of the test bacteria. Conclusion: These three basidiomycetous mushrooms have antibacterial activity. After further research, their activity can be employed in medical science.

Can mushrooms fix atmospheric nitrogen?

It is generally reported that fungi like Pleurotus spp. can fix nitrogen (N2). The way they do it is still not clear. The present study hypothesized that only associations of fungi and diazotrophs can fix N2. This was tested in vitro. Pleurotus ostreatus was inoculated with a bradyrhizobial strain nodulating soybean and P. ostreatus with no inoculation was maintained as a control. At maximum mycelial colonization by the bradyrhizobial strain and biofilm formation, the cultures were subjected to acetylene reduction assay (ARA). Another set of the cultures was evaluated for growth and nitrogen accumulation. Nitrogenase activity was present in the biofilm, but not when the fungus or the bradyrhizobial strain was alone. A significant reduction in mycelial dry weight and a significant increase in nitrogen concentration were observed in the inoculated cultures compared to the controls. The mycelial weight reduction could be attributed to C transfer from the fungus to the bradyrhizobial strain, because of high C cost of biological N2 fixation. This needs further investigations using 14C isotopic tracers. It is clear from the present study that mushrooms alone cannot fix atmospheric N2. But when they are in association with diazotrophs, nitrogenase activity is detected because of the diazotrophic N2 fixation. It is not the fungus that fixes N2 as reported earlier. Effective N2 fixing systems, such as the present one, may be used to increase protein content of mushrooms. Our study has implications for future identification of as yet unidentified N2 systems occurring in the environment.