Background The use of chemical fungicides against fungal pathogens adversely affects soil and plant health thereby resulting in overall environmental hazards. Therefore, biological source for obtaining antifungal agents is considered as an environment-friendly alternative for controlling fungal pathogens. Results In this study, seven endophytic bacteria were isolated from sugarcane leaves and screened for its antifungal activity against 10 fungal isolates belonging to the genera Alternaria, Cochliobolus, Curvularia, Fusarium, Neodeightonia, Phomopsis and Saccharicola isolated from diseased leaves of sugarcane. Among the seven bacterial isolates, SCB-1 showed potent antagonistic activity against the tested fungi. Based on the phenotypic data, Fatty Acid Methyl Esters (FAME) and 16S rRNA gene sequence analysis, the isolate SCB-1 was identified as Bacillus subtilis . The bacterial isolate was screened negative for chitinase production; however, chloroform and methanol extracts of the bacterial culture caused significant inhibition in the growth of the fungal isolates on semisolid media. Volatile component assay showed highest inhibitory activity against Saccharicola bicolor (SC1.4). A PCR based study detected the presence of the genes involved in biosynthesis of surfactin, bacillaene, difficidin, macrolactins and fengycin. Mass spectrometric analysis of the bacterial extract detected the presence of antifungal lipopeptide surfactin, but other metabolites were not detected. The biocontrol activity of the bacterial isolate was established when bacterial pretreated mung bean seeds were able to resist Fusarium infection, however, the untreated seeds failed to germinate. Conclusion The antifungal potential of isolate Bacillus subtilis SCB-1 was established against taxonomically diverse fungal pathogens including the genera Saccharicola , Cochliobolus, Alternaria and Fusarium . The potent antifungal compound surfactin as well as volatiles produced by the bacterial isolate could be responsible for its bio-control activity against fungal infections. Electronic supplementary material The online version of this article (10.1186/s12866-019-1440-8) contains supplementary material, which is available to authorized users.

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Association of bacteria with fungi is a major area of research in infection biology, however, very few strains of bacteria have been reported that can invade and reside within fungal hyphae. Here, we report the characterization of an endofungal bacterium Serratia marcescens D1 from Mucor irregularis SS7 hyphae. Upon re-inoculation, colonization of the endobacterium S. marcescens D1 in the hyphae of Mucor irregularis SS7 was demonstrated using stereo microscopy. However, S. marcescens D1 failed to invade into the hyphae of the tested Ascomycetes (except Fusarium oxysporum) and Basidiomycetes. Remarkably, Serratia marcescens D1 could invade and spread over the culture of F. oxysporum that resulted in mycelial death. Prodigiosin, the red pigment produced by the Serratia marcescens D1, helps the bacterium to invade fungal hyphae as revealed by the increasing permeability in fungal cell membrane. On the other hand, genes encoding the type VI secretion system (T6SS) assembly protein TssJ and an outer membrane associated murein lipoprotein also showed significant up-regulation during the interaction process, suggesting the involvement of T6SS in the invasion process.

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A variety of cultivated mushrooms in Northeast India are well known for their taste, nutritional and medicinal benefits. Many wild-growing mushrooms are also consumed due to their exotic flavours and tastes; however, the scientific exploration of their nutritional and bioactive properties is still negligible. In the present study, the 32 wild edible mushroom samples of 11 species collected from different parts of Northeast India were evaluated for their proximate composition, mineral and vitamin (ascorbic acid and riboflavin) contents, antioxidant and antihaemolytic activity, and profiles of organic and phenolic acids. Lentinus sajor-caju and Lentinus squarrosulus had the highest carbohydrate content (49.80 g/100 g dry weight (d.w.) and 46.36 g/100 g d.w., respectively), crude protein content (20.72 g/100 g d.w. and 20.54 g/100 g d.w., respectively) and a considerable content of minerals. The highest fat content was determined in Lentinus velutinus (7.17 g/100 g d.w.). Among the minerals, potassium was found as the most abundant in all the samples. The extracts of L. sajor-caju, L. squarrosulus, and Pleurotus pulmonarius were characterized by the highest antioxidant activity, while these of L. sajor-caju, Pleurotus ostreatus, P. pulmonarius and Agaricus bisporus showed the highest antihaemolytic potential. The HPLC analysis allowed determining the high contents of ascorbic acid and a few organic and phenolic acids such as lactic acid, gallic acid, 3,4-dihydroxybenzoic acid and trans-cinnamic acid in the tested mushrooms. Other compounds viz. citric acid, caffeic acid, riboflavin, vanillic acid, pyruvic acid, and p-coumaric acid were detected with variations. This study established the nutritional and health benefits of wild edible mushrooms of Northeast India region for consumption as functional foods in the human diet.