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Lichen, a symbiotic form of fungi and algae has been known for its metabolites, but, much of the metabolites remain unexplored. It's excellent biomedical potential with active substances are being applied for medicinal purposes for the past few years. By considering the active compounds, the present study aims at reporting the anti-microbial and anti-oxidant activities of less explored lichen, Ramalina inflata. Lichen sample was collected from Kolli hills of Eastern Ghats in the range of above 1000MSL. Further, it was subjected to extraction (Soxhlet) using five solvents and purification of bioactive metabolites. The result indicated the compounds that were present in the different extracts were found to be salazinic acid, divaricatic acid and some triterpenes. Antimicrobial activity of methanolic extract showed a high zone of inhibition against Klebsiella pneumoniae (13.01±0.12 mm). Petroleum ether showed the best inhibition against Staphylococcus aureus with 10.17±0.07 mm and against Candida krusei with an inhibition of 8.47±0.08 mm. Antioxidant assays of Phenolics, DPPH, Ferric reducing power assay, CUPRAC, and Phosphomolybdenum assay were done for various crude extracts. The result observed that benzene extract showed a high content of total phenolics, which was 30.790±0.903 μg/ml whereas, its percentage of inhibition in DPPH assay was 12.987%. The petroleum extract of R. inflata showed a moderate activity in ferric ion reducing power assay and molybdenum reducing assay and a very low cupric ion reducing capability. Methanol extract showed a high cupric ion reducing power with an optical density of 0.829±0.036.

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One of the most commonly occurring bacteria, Bacillus subtilis, can produce a wide variety of secondary metabolites. In this study, the antimicrobial effect of B. subtilis KSRLAB3 against Vibrio alginolyticus was optimized using the Plackett–Burman design (PBD) method, response surface methodology (RSM), and genetic algorithm (GA). Initially, the effects of carbon source, nitrogen source, NaCl concentration, pH, temperature, and incubation time on antimicrobial effects were studied. Among the carbon and nitrogen sources investigated, mannose and peptone elicited maximum antimicrobial effect. Using PBD, the most significant variables that influence the antimicrobial effect were identified, including incubation time, peptone concentration, and temperature. The optimum conditions required for attaining maximum antimicrobial effect was identified using the RSM‐GA hybrid method, and the optimum condition includes 49.999 h of incubation time, 4.39 g/L of peptone concentration, and 27.629°C of incubation temperature. The confirmatory experiments performed around the optimum condition showed a zone of inhibition of 35 ± 0.52 mm. Methanolic extract also proved the presence of antibacterial lipopeptide surfactin. Therefore, the RSM‐GA hybrid method was successfully used in this study to model the antimicrobial effect of B. subtilis KSRLAB3 against V. alginolyticus. The effective inhibition of V. alginolyticus can be investigated further for the development of antifouling coatings.

The objective of this study is to find the effect on DI-CI naturally aspirated engine influenced by Manilkara Zapota biodiesel blends doped with green synthesized silver nanoparticles. The Manilkara Zapota biodiesel is used as base fuel and green synthesized silver nanoparticle as nanoadditive. The nanoparticle is prepared with the leaf extracts of Manilkara Zapota. The different test fuel blends are prepared with different concentrations of 40, 80, and 120 ppm of silver nanoparticles such as B100, B20, B20AgNP40ppm, B20AgNP80ppm, B20AgNP120ppm and diesel. The fuel properties are measured as per ASTM standard and compared the results with and without nanoparticles are presented in this paper. To validate the test fuel by conduct the experimental investigation on a single cylinder DI-CI naturally aspirated engine loaded with eddy current dynamometer attached with combustion pressure transducer. The experimental results proved test fuel B20AgNP80ppm exhibits better results compared to other test fuels. The brake thermal efficiency of 33.31% was obtained for B20AgNP80ppm fuel which is 2.83% and 1.02% higher than B20 and diesel. The maximum reduction of CO obtained for the fuel blend B20 with addition of 80 ppm of AgNP were 33.33% and 37.5% compared to B20 and diesel. The UHC emission reduced by 32.6% and 38% for B20AgNP80ppm compared to B20 and diesel. It is also found that lower NOx and smoke for B20AgNP80ppm blend compared to B20 and diesel. The maximum cylinder pressure and heat release rate were achieved for B20AgNP80ppm compared to other blends.

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The silver nanoparticles (AgNP's) were synthesized using green synthesis and chemical synthesis method. The nanoparticles synthesized using green synthesis (boiled extract and normal extract) were compared for the difference in various properties after characterization using X-ray diffraction (XRD), Fourier Transform Infra-Red spectroscopy (FT-IR) and Atomic Force Microscopy (AFM). There is not much difference between the AgNP's synthesized using both the methods. The chemically synthesized AgNP's were also characterized. FTIR analysis revealed that there is a strong peak of absorbance at 1379 cm -1 on comparison with the control. XRD analysis is used to find the nature and size of the silver nanoparticle. The silver nanoparticles are found to be more stable in distilled water than the deionized water and tap water. The antimicrobial activity is high for the boiled extract sample when compared with other samples. The effect of AgNP's on Vigna radiata is studied by exposing the seeds in time intervals and allowing them to germinate. The comparison was done by estimation of chlorophyll and protein. Based on the studies it could be said that if the exposure to silver nanoparticles increases the content of the plant will be affected.