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BackgroundMicroalgae is considered a promising source for biofuel and bioenergy production, bio-remediation and production of high-value bioactive compounds, but harvesting microalgae is a major bottleneck in the algae based processes. The objective of this research is to mimic the growth of natural lichen and develop a novel biofilm platform technology using filamentous fungi and microalgae to form a lichen type of biofilm “mycoalgae” in a supporting polymer matrix.ResultsThe possibility of co-existence of Chlorella vulgaris with various fungal cultures was tested to identify the best strain combination for high algae harvest efficiency. The effect of different matrices for cell attachment and biofilm formation, cell surface characterization of mycoalgae biofilm, kinetics of the process with respect to the algae-fungi cell distribution and total biomass production was studied. Mycoalgae biofilm with algae attachment efficiency of 99.0 % and above was achieved in a polymer-cotton composite matrix with glucose concentration of 2 g/L in the growth medium and agitation intensity of 150 rpm at 27 °C. The total biomass in the co-culture with the selected strain combination (Mucor sp. and Chlorella sp.) was higher than the axenic cultures of fungi and algae at the conditions tested.ConclusionsThe results show that algae can be grown with complete attachment to a bio-augmenting fungal surface and can be harvested readily as a biofilm for product extraction from biomass. Even though, interaction between heterotrophic fungi and phototrophic algae was investigated in solid media after prolonged contact in a report, this research is the first of its kind in developing an artificial lichen type biofilm called “mycoalgae” biofilm completely attached on a matrix in liquid cultures. The mycoalgae biofilm based processes, propounds the scope for exploring new avenues in the bio-production industry and bioremediation.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-016-0533-y) contains supplementary material, which is available to authorized users.

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Surface modification of titanium and titanium alloy is one of the attractive methods to improve the biological affinity of orthopaedic and dental devices. Although osteointegration is enhanced by surface modifications, bacterial related infections sometimes lead to implant failure and secondary surgery. In the present study, attempts were made to incorporate antimicrobial agent silver into titanium metal pre-treated with H 2 O 2 . Fine nano network structures of hydrated titania uniformly formed by the H 2 O 2 treatment were decorated with silver particles of 5-10 nm by subsequent AgNO 3 , and, these silver particles remained stable over titania network even after heat treatment. Antibacterial study of titanium metal subjected to H 2 O 2 -AgNO 3 showed zone of inhibition in Staphylococcus aureus compared to H 2 O 2 pre-treated and untreated control specimen. Steady release of silver from thus treated titanium metals into simulated body fluid indicates that these silver particles are released as silver ions and are responsible for the antibacterial activity. About 99.7% bacterial killing efficiency was observed for 6-8 ppm (1mM AgNO 3 ) silver containing Ti surface is optimised as the highest tolerable silver limit. The cytotoxicity assay and cell adhesion study on MG63 osteosarcoma cell lines confirmed the present silver concentration does not show any toxicity. Further, bone like apatite formation of chemically and heat-treated titanium in simulated body fluid indicates this surface modification method could be suitable in various medical devices.