Vibrio harveyi biofilm as immunostimulant candidate for high-health pacific white shrimp, Penaeus vannamei farming.

The study was to develop Vibrio harveyi biofilm-based novel microbial product and its oral delivery for high health Penaeus vannamei farming. Yield of bacterial biofilm was optimized on chitin substrate (size: <360, 360-850 and 850-1250 µm; concentration: 0.3, 0.6 and 0.9%) in tryptone soy broth (0.15%). The biofilm was characterized by crystal violet assay, SEM and LSCM imaging; protein profiling by SDS-PAGE and LC-ESI-MS/MS. The immune stimulatory effect of the biofilm in yard experiments was evaluated by relative quantification of immune genes using real-time PCR effect on overall improvement on health status under field trials. The highest biofilm yield (6.13 ±â€¯0.2 × 107 cfu/ml) was obtained at 0.6% of <360 µm chitin substrate. The biofilm formation was stabilized by 96 h of incubation at 30 °C. Protein profiling confirmed expression of six additional proteins (SDS-PAGE) and 11 proteins were differentially expressed (LC-ESI-MS/MS) in biofilm cells over free cells of V. harveyi. Oral administration of the biofilm for 48 h confirmed to enhance expression of antimicrobial peptides, penaeidin, crustin and lysozyme in P. vannamei. Further Oral administration of biofilm for two weeks to P. vannamei (1.8 ±â€¯0.13 g) improved the growth (2.66 ±â€¯0.06 g) and survival (84.44 ±â€¯1.82%) compared to control (2.15 ±â€¯0.03 g; 70.94 ±â€¯0.66%) Nursery trials showed a significant reduction in occurrence of anatomical deformities like antenna cut (12.67 ±â€¯0.66%), rostrum cut (4.66 ±â€¯0.87%), and tail rot (3.33 ±â€¯0.88%), compared to animals fed with normal diet which was 24.33 ±â€¯2.72; 14 ±â€¯1.52 and 10.66 ±â€¯1.45% respectively. In vitro and in vivo studies suggest inactivated biofilm cells of V. harveyi on chitin substrate express additional antigenic proteins and when administered orally through feed at regular intervals stimulates immune response and improve growth, survival and health status of shrimp.

Mannich base limits Candida albicans virulence by inactivating Ras-cAMP-PKA pathway.

Mannich bases and its derivatives are regarded as supreme pharmacophores in therapeutics. The study investigates the antimycotic potential of Mannich bases, 1-((1H-benzimidazol-1-yl) methyl) urea (C1) and 1-((3-hydroxynapthalen-2-yl) methyl) thiourea (C2), against Candida albicans. Biofilm and hyphal inhibitory activities of the Mannich bases were tested by crystal violet quantification, fluorescence imaging cAMP rescue, qRT PCR, and by molecular docking analysis. The compounds inhibited the biofilms of C. albicans and restrained the filamentation abilities of the pathogen. Structure-activity relationship studies revealed that the presence of urea or thiourea moiety in the tail section is essential for interacting with adenylate cyclase (AC). The Mannich bases seemed to block Ras-cAMP-PKA pathway by inhibiting second messenger activity required for hyphal induction and biofilm formation. In conclusion, the study warrants point-of-care testing of C1/C2 and provides a starting point for deriving several structurally modified Mannich bases which might plausibly replace the prevailing antimycotic drugs in future.

Environmentally available biowastes as substrate in microbial fuel cell for efficient chromium reduction.

Dual chambered microbial fuel cells with Potassium dichromate (22 g/L, MFC-1) and tannery effluent waste water containing 26 mg/L (MFC-2), 5 mg/L (MFC-3) of Cr(VI) as catholyte, sweet lime waste inoculated by cowdung as anolyte and graphite electrodes were used to reduce toxic Cr(VI) to Cr(III) with simultaneous power generation. Cr (VI) in the cathode chamber reduced to Cr2O3 within 24 h. Complete reduction of Cr(VI) from tannery effluents by microbial fuel cell is noticed within 10 days. The 16 s rRNA sequencing studies demonstrated presence of Geobacter Metallireducens in mixed culture bacteria in anaerobic anode. The power density of the device is 396.7 mW/m2on day1which is 7.2 times higher than literature data of 55.5 mW/m2. The processes involved on the biofilm/electrolyte interface and graphite/electrolyte interface is studied by Electrochemical Impedance Spectroscopy. Electrochemical studies demonstrated the active growth of biofilm on anode which reduces charge transfer resistance from day 1 to day 25. The concentration of Cr(VI) reduced in the present studies are approximately 1000 times higher than those reported in the literature.