Biopolymers have been used in packaged foods to tackle environmental hazards due to their biodegradability and non-toxic nature. In addition to these merits, they have also several demerits such as poor mechanical properties and low resistance towards water. Nanomaterials have attracted great interest in recent years due to their phenomenal properties that makes them precedent in applications for food packaging as they enhance the mechanical, thermal and gas barriers properties, without compromising with the ability to become non-toxic and biodegradable. The most important nanomaterials used in food packaging are montmorillonite (MMT), zinc oxide (ZnO-NPs) coated silicate, kaolinite, silver NPs (Ag-NPs) and titanium dioxide (TiO 2 NPs) as these, nanomaterials coated films makes a barrier against oxygen, carbon dioxide and favour compounds. They also possess oxygen scavenging capability, antimicrobial activity and tolerance towards temperature. The most difficult task related to the preparation of these nanocomposites is their complete distribution within the polymer matrix and their compatibility. Therefore, there is an increasing demand for improvement in the performance of nano-packaging materials including mechanical stability, degradability and effectiveness of antibacterial property.

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BackgroundParticulates of nanometers size have occupied a significant area in the field of medicinal and agricultural purposes due to their large surface-to-volume ratio and exceptional physicochemical, electronic and mechanical properties. Myconanotechnology, an interface between mycology and nanotechnology is budding nowadays for nanoparticle-fabrication using fungus or its metabolites. In the present study, we have isolated and characterized a novel phosphate solubilizing fungus B. tetramera KF934408 from rhizospheric soil. This phosphatase releasing fungus was subjected to extracellular synthesis of metal nanoparticles by redox reaction.ResultsSilver (AgNPs) and gold nanoparticles (AuNPs) were characterized by dynamic light scattering and transmission electron microscopic analysis. The formulated AgNPs were irregular shaped with a size ranging between 54.78 nm to 73.49 nm whereas AuNPs were spherical or hexagonal, with a size of 58.4 and 261.73 nm, respectively. The nanoparticles were assessed for their antibacterial and antifungal efficacy. The results showed effective antimicrobial activity of AgNPs against Bacillus cereus, Staphylococcus aureus, Enterobacter aeroginosa and Trichoderma sp. at higher concentrations, however, AuNPs possessed only moderate antibacterial efficacy while they found no antifungal activity. Cytotoxicity analysis of nanoparticles on J774 and THP1 α cell lines revealed the dose dependence in case of AgNPs, while AuNPs were non-toxic at both low and high doses. Furthermore, significant elevation of intracellular ROS was observed after 4 h of incubation with both the nanoparticles. The capping of fungal proteins on the particulates might be involved in the activities demonstrated by these inert metal nanoparticles.ConclusionIn conclusion, the findings showed that the metal nanoparticles synthesized by fungus B. tetramera could be used as an antimicrobial agents as well as cost effective and nontoxic immunomodulatory delivery vehicle.Electronic supplementary materialThe online version of this article (doi:10.1186/s12866-015-0391-y) contains supplementary material, which is available to authorized users.

The need for identification of soil microbial community mainly depends on direct extraction of DNA from soil, a multifaceted environment that is a major pool for microbial genetic diversity. The soil DNA extraction procedures usually suffer from two major problems, namely, inappropriate rupturing of cells and contamination with humic substances. In the present study, five protocols for single type of rhizospheric soil were investigated and their comparison indicated that the inclusion of 120 mM phosphate buffered saline (PBS) for washing and mannitol in the lysis buffer allowed the processing of soil sample in minimal time with no specific equipment requirement. Furthermore, DNA purity and yield were also improved, which allowed the exploitation of genetic potential of soil microbes within soil sample thereby facilitating the amplification of metagenomic DNA. The effectiveness of methods was analyzed using random amplification of polymorphic DNA. The banding patterns revealed that both the abundance and the composition of indigenous microbial community depend on the DNA recovery method.