Sun-screening bioactive compounds mycosporine-like amino acids in naturally occurring cyanobacterial biofilms: role in photoprotection.

AIMS: To investigate the occurrence of UV sunscreening biomolecules and their role in photoprotection in cyanobacterial biofilms growing in brightly lit habitats with high UV fluxes. METHODS AND RESULTS: High performance liquid chromatography with photodiode-array and mass spectrometry revealed the presence of mycosporine-like amino acids (MAAs) shinorine (λ(max) 334 nm, m/z 333), porphyra-334 (λ(max) 334 nm, m/z 347), mycosporine-glycine (λ(max) 310 nm, m/z 246) and palythinol (λ(max) 332 nm, m/z 303). Two unknown MAAs with λ(max) at 320 (m/z 289) and 329 nm (m/z 318) were also found. Biosynthesis of MAAs was found to increase with increase in exposure time under UV radiation. The MAAs from biofilms showed efficient radical scavenging activity as well as photoprotective potential on the survival of UV-treated Escherichia coli cells. CONCLUSIONS: Biosynthesis of photoprotectants is an important mechanism to prevent photodamage in Cyanobacteria. UV-induction and photoprotective function of MAAs may facilitate them to perform important ecological functions under harsh environmental conditions. SIGNIFICANCE AND IMPACT OF THE STUDY: There are very few reports on qualitative and quantitative characterization of different MAAs in cyanobacterial biofilms. Due to strong UV absorption and photoprotective function, MAAs may be used as an active ingredient in cosmetic and other pharmaceutical industries.

Suppression of reactive oxygen species and nitric oxide by Asparagus racemosus root extract using in vitro studies.

Recent clinical and experimental data showed the involvement of reactive oxygen species/nitrogen species (ROS/RNS) in many human pathophysiological conditions. Antioxidant activity of the aqueous (ARA) and ethanolic extracts (ARE) of Asparagus racemosus (AR) root were evaluated in a series of in vitro assays including ROS generation in chemicals and biological model systems. The dose-dependent ARA and ARE extracts showed the scavenging activity against DPPH (IC50 = 60.7 and 52.5 microg/ml), nitric oxide (IC50 = 141.9 and 63.4 microg/ml), superoxide (IC50 = 221 and 89.4 microg/ml), hydroxyl (IC50 = 318.7 and 208.8 microg/ml) and ABTS.+ (IC50 = 134.5 and 71.9 microg/ml) radicals. The antioxidant capacity of ARA and ARE were assessed for their reducing power using FRAP (Ferric Reducing antioxidant power) and potassium ferricyanide reducing methods as well as free radical scavenging capacity by TEAC (Trolox Equivalent Antioxidant Capacity) method. ARA and ARE extracts were also found to be effective at suppressing lipid peroxidation induced by Fe2+/ascorbate system in rat liver mitochondrial preparation (IC50 = 511.7 and 309.2 microg/ml, respectively). Further, ARA and ARE root extracts significantly decreased (P < 0.05) copper-mediated human LDL oxidation by prolongation of lag phase time with decline in oxidation rate, maximal yield of conjugated dienes, lipid hydroperoxides and malondialdehyde concentrations. The addition of ARA and ARE root extracts to human serum significantly reduced (P < 0.05) the formation of lipid peroxidation in medium. Trolox, alpha-tocopherol and mannitol were tested similarly to compare their antioxidant activities. In conclusion, antioxidant activity of ARE as compared to ARA extract is more effective which act as hydrogen donors, metal ion chelators, reducing agents, radical scavengers and anti-lipid peroxidative. These effects are attributed to the high amount of lipophilic phenolics content of ARE root extract.

Ultrastructure of the cyanobacterium Nostoc muscorum and exploitation of the culture for hydrogen production.

An effect of various physico-chemical parameters on nitrogenase-catalyzed oxygen-free hydrogen production by Nostoc muscorum was demonstrated. More hydrogen was produced in the light than in the dark. Optimum temperature was 40 degrees C Various sugars increased hydrogen production whereas on easily metabolized nitrogen sources it was inhibited. The production was sensitive to salinity and Fe3+, Cu2+, Zn2+ and Ni2+ ions. Ultrastructural study revealed many electron-dense layers outside the cell-wall area that have not been observed earlier.

Decolorization of synthetic textile dyes by lignin peroxidase of Phanerochaete chrysosporium.

Neem hull waste (containing a high amount of lignin and other phenolic compounds) was used for lignin peroxidase production by Phanerochaete chrysosporum under solid-state fermentation conditions. Maximum decolorization achieved by partially purified lignin peroxidase was 80% for Porocion Brilliant Blue HGR, 83 for Ranocid Fast Blue, 70 for Acid Red 119 and 61 for Navidol Fast Black MSRL. The effects of different concentrations of veratryl alcohol, hydrogen peroxide, enzyme and dye on the efficiency of decolorization have been investigated. Maximum decolorization efficiency was observed at 0.2 and 0.4 mmol/L hydrogen peroxide, 2.5 mmol/L veratryl alcohol and pH 5.0 after a 1-h reaction, using 50 ppm of dyes and 9.96 mkat/L of enzyme.

Ultrastructure of the fresh water cyanobacterium Anabaena variabilis SPU 003 and its application for oxygen-free hydrogen production.

Photoproduction of hydrogen has been studied as one of the ways to produce a clean, renewable energy source. Ultrastructure of the selected strain Anabaena variabilis SPU 003, a heterocystous cyanobacterium, has been done to understand the cell structure. The organism was found to be essentially a dark hydrogen producer. While pH had no significant effect on hydrogen production, optimum temperature was found to be 30 degrees C. Various sugars increased the production of hydrogen while the presence of various nitrogen sources inhibits the production. The production of hydrogen is highly sensitive to salinity and micronutrients.

Characterization of the extracellular polysaccharide produced by a marine cyanobacterium, Cyanothece sp. ATCC 51142, and its exploitation toward metal removal from solutions.

Cyanobacterium, Cyanothece sp. ATCC 51142 produces an exopolysaccharide at a high level. Physical analysis of the exopolysaccharide (EPS), such as nuclear magnetic resonance, infrared spectrum, were done to determine its possible structure. Thermal gravimetric analysis, differential scanning calorimeter, and differential thermal analysis of the polymer were done to find out the thermal behavior. Calcium content within the sample was found out. Some of the physicochemical properties, such as relative viscosity, specific viscosity, and intrinsic viscosity of the EPS were studied under different conditions. The phenomenon of gel formation by the EPS was investigated for its potential application in metal removal from solutions.

Anaerobic upflow fixed-film bioreactor for biomethanation of salty cheese whey.

In order to develop a suitable reactor for the biomethanation of high-strength salty cheese whey, the performance of anaerobic upflow fixed-film reactors packed with different support materials, such as charcoal, gravel, brick pieces, pumice stones, and PVC pieces, has been studied. The charcoal-bedded reactor gave the best performance, with the maximum gas production (3.3 L/L digester/d) and an enriched methane content (69% CH4). Temperature and hydraulic retention time were optimized, with the ultimate aim of improving biomethanation. Maximum gas production (3.3 L/L digester/d) was achieved at a hydraulic retention time of 2 d at 40 degrees C.

Biomethanation of a mixture of salty cheese whey and poultry waste or cattle dung. A study of effect of temperature and retention time.

This paper describes the results of a study aimed at improving the efficiency of anaerobic digestion of salty cheese whey in combination with poultry waste or cattle dung. Best results were obtained when salty cheese whey was mixed with poultry waste in the ratio of 7:3, or cattle dung in the ration of 1:1, both on dry weight basis giving maximum gas production of 1.2 L/L of digester/d with enriched methane content of 64% and 1.3 L/L of digester/d having methane content of 63% respectively. Various conditions such as temperature and retention time have been optimized for maximum process performance.

Stability of invertase in reverse micelles.

The stability of invertase was studied under various conditions, including at 75 degrees C, in presence of stabilizers (sorbitol and glycerol) at 75 degrees C, and in the presence of denaturants (urea and trichloroacetic acid) at 37 degrees C in reverse micelles. Stability of the invertase in reverse micelles was found to be improved over that of the enzyme in bulk aqueous solution. Sorbitol could enhance enzyme stability as it does in the bulk aqueous system. The stabilizing effect of glycerol was reduced in reverse micelles. The denaturation pattern of urea remains unaltered. However, the denaturation effect of trichloroacetic acid has been reduced in reverse micelles.

Photo-osmosis through liquid membrane bilayers. Studies on mixture of bacteriorhodopsin with cytochrome-C, myoglobin, or hemoglobin.

The effect of cytochrome-C, hemoglobin, and myoglobin on photo-osmosis through liquid membrane bilayers generated by bacteriorhodopsin (BR) has been studied. The magnitude of photo-osmotic velocity was found to be much greater when BR was combined with any one of the three pigments than that of BR alone. This has been because of the exclusion of protons and electrons in the illuminated compartment by the action of light, where one acts as the acceptor for the others. The rate of light-induced volume flux of the combined system depends on temperature, intensity, and wavelength of incident light, and the nature and concentration of electron donors and acceptors.

Anaerobic digestion of a mixture of cheese whey, poultry waste and cattle dung: a study of the use of adsorbents to improve digester performance.

This paper-describes the results of a study aimed at improving the efficiency of anaerobic digestion of a mixture of cattle dung, poultry waste and cheese whey at a ratio of 2 : 1 : 3 (w/w on dry weight basis) in terms of total gas production, methane content and process stability by adding various adsorbents. The adsorbents appeared to improve the digester performance, for example about a two-fold enhancement in total gas production with 17% enriched methane content were achieved with the addition of 4 g litre(-1) of silica gel.

Effect of temperature and retention time on biomethanation of cheese whey-poultry waste-cattle dung.

Various conditions, such as temperature, total solid content, cattle dung-poultry waste-cheese whey ratio, retention time and stirring, were optimized with an ultimate aim of improving anaerobic digestion. Maximum gas production (2.2 litres litre(-1) of digester day(-1)) with enriched methane content (62% CH(4)) was found with a retention time of 10 days, having a loading rate of 6.0 g total solid litre(-1) of digester day(-1) at 40 degrees C, and total solid of 6% (w/v) using a mixture of cattle dung, poultry waste and cheese whey in the ratio of 2:1:3 (w/w).

Production of α-amylase fromHalobacterium halobium.

Maximum production of extracellular α-amylase activity inHalobacterium halobium was at 40°C in a medium containing 25% (w/v) NaCl, 1% (w/v) soluble starch and 1% (w/v) peptone, in presence of 0.1MM ZnSO4 after 5 days in shaking cultures. The amylase had optimal activity at pH 6.5 in the presence of 1 to 3% (w/v) NaCl at 53°C.

Effect of mixture of surfactants and adsorbents on anaerobic digestion of water hyacinth-cattle dung.

In an effort to improve the anaerobic digestion of water hyacinth-cattle dung with enriched methane content, the effects of mixtures of surfactant-surfactant, adsorbent-adsorbent and surfactant-adsorbent have been studied in various combinations. Among the combinations tested, bentonite and gelatin, gelatin and Tegoprens 43, sodium lauryl sulfate and Tegoprens 42, and Tegoprens 47 and Tegoprens 63 showed more than a 100% increase in gas production with higher methane yield.

Formation of cellulases by co-culturing ofTrichoderma reesei andAspergillus niger on cellulosic waste.

A cellulase system possessing high hydrolytic and ß-glucosidase activity was obtained by co-culturingTrichoderma reesei andAspergillus niger by a new approach using semi-solid fermentation of lignocellulosic materials. Various types of pretreatments were used for making the cellulose easily accessible to enzymatic attack. The optimal water content for maximum activity of the mixed fermentation was investigated. A more concentrated enzyme preparation could be obtained by semi-solid state fermentation than by conventional submerged fermentation.