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Green route biosynthesis of silver nanoparticles (SNPs) using methanol extract of Oscillatoria sp. was investigated. The nanoparticles (OsSNPs) were characterized by UV-Vis spectrophotometry, FTIR, SEM, Thermogravimetry, EDX and DLS. The antibacterial, antibiofilm and in vitro cytotoxicity activity of the OsSNPs was determined. Surface Plasmon Resonance peak was at 500 nm. Functional groups such as hydroxyl; alcohol, phosphate, and amine among others were responsible for the capping and stabilization of proteins in the nanoparticles. The OsSNPs were spherical with size of 10 nm and are thermostable to an extent without totally losing its weight. EDX analysis revealed a strong signal of silver element. DLS shows the particle diameter average of 0.000 nm and 558.1 nm with a polydispersity index of 0.580. The OsSNPs had effective antibacterial activity against the test bacterial pathogens with zone of inhibition ranged from 1 - 21 mm. OsSNPs exhibited strong antibiofilm activity. However, the toxicity of the OsSNPs to Artemia salina (brine shrimp) was observed to be insignificant with the highest mortality at 4000 μg/mL and lethal dose (LC50) of 2630.3 μg/mL. Greenly synthesized OsSNPs had effective antibacterial potency and low cytotoxicity which suggests its use in biomedical and pharmacological applications.

HighlightsCharacterization, antioxidant and immunomodulatory potential of exopolysaccharide (EPS) produced by wild and mutant Weissella confuse was evaluated.Wild Weissella confusa (WWCEPS) produced the highest EPS compare to the mutant strain.The EPS were heteropolysaccharides containing eight (8) monosaccharides in which galactose had the highest composition (34.60 mg/g and 33.47 mg/g EPS) in wild Weissella confusa EPS (WWCEPS) and mutant Weissella confusa EPS (MWCEPS).WWCEPS and MWCEPS had antioxidant capacity and WWCEPS had the highest DPPH capacity, total antioxidant activity, hydrogen peroxide and reducing power activity (71%, 1.88%, 86.7% and 1.85%).Wild and mutant Weissella confusa EPS exhibited immunomodulatory activity on the treated mice.

Biological evaluation of exopolysaccharides (EPS) produced by wild type and mutant Lactobacillus delbureckii (EPSWLD and EPSMLD) was investigated. Varying degrees of functional groups associated with polysaccharides were present thus confirming the EPS. The EPSs had strong antioxidant potential in a dose dependent (0.5-10 mg/ mL) manner. EPSWLD and EPSMLD exhibited the highest 1,1-diphemy 1-2-picryl-hydrazyl (DPPH) activity (73.4 % and 65.6 %), total antioxidant activity (1.80 % and 1.42 %), H 2 O 2 scavenging activity (88.5 % and 78.6 %) and Ferric Reducing Antioxidant Power (FRAP) (1.89 % and1.81 %) at 10 mg/mL respectively. WLD and MLD were highly susceptible to chloramphenicol, cotrimoxazole, tetracycline, erythromycin and ceftazidine and resistant to cefuroxime, gentamicin and cloxacillin. The EPSs had antibacterial activity against the test pathogens. B. subtilis and S. aureus had the highest susceptibility (26.0 mm and 23.0 mm). EPSMLD modulate the highest IgG, IgA and IgM production (68-126 mg/dL and 67-98 mg/dL and 64-97 mg/dL) in the treated tumor induced mice (TTIM). EPSWLD and EPSMLD exhibited reduction capability on the CEA level (3.99-4.35 ng/L and 4.12-4.23 ng/L) of the TTIM. EPSWLD TTIM had the highest amount of RBC, WBC and PCV (5.6 Â 10 12 %, 68000% and 42%). The EPS increased the lifespan of TTIM. In conclusion EPSWLD and EPSMLD had strong biological potential with pharmacological and neutraceutical activity.

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