Explore the vast range of titles available.

Fucoidanase and alginate lyase are promising biocatalysts for several biotechnological applications. The sequentially extracted fucoidan and alginate from the brown macroalgae Sargassum latifolium were used for the optimization of a cost-effective culture medium for fucoidanase and alginate lyase production by the marine fungus Dendryphiella arenaria. Plackett–Burman statistical design was conducted for initial determination of the importance of 11 independent variables on enzyme potentiation, and the significant variables were further optimized using Box–Behnken design. The optimum conditions for fucoidanase production were fucoidan (1.5% w/v), NaCl (1.5%), urea (0.3%), and incubation period (2 days), which gives ~ 4 U mL−1 of crude fucoidanase. While, alginate (1.5% w/v), NaCl (4%), NH4Cl (0.3%), and incubation period (6 days) were the optimum conditions that enhanced alginate lyase production to ~ 24 U mL−1. Additionally, a new protocol for the enzymatic saccharification of fucoidan and alginate was optimized using Box–Behnken design with respect to substrate concentration, enzyme dosage, and temperature. The enzymatic saccharification of citric acid-extracted fucoidan gave a maximum yield of reducing sugar 365 mg g−1 fucoidan, while the alkali-extracted alginate gave 439.66 mg g−1 alginate. The results showed that the two enzymes could be exploited for the efficient production of reducing sugars from fucoidan and alginate, which are the key substrate for producing biofuels from brown macroalgal biomass.

Agarase is a promising biocatalyst for several industrial applications. Agarase production was evaluated by the marine fungus Dendryphiella arenaria utilizing Palisada perforata as a basal substrate in semi-solid state fermentation. Seaweed biomass, glucose, and sucrose were the most significant parameters affecting agarase production, and their levels were further optimized using Box-Behnken design. The maximum agarase activity was 7.69 U/mL. Agarase showed a degree of thermostability with half-life of 99 min at 40 °C, and declining to 44.72 min at 80 °C. Thermodynamics suggested an important process of protein aggregation during thermal inactivation. Additionally, the enzymatic saccharification of the seaweed biomass using crude agarase was optimized with respect to biomass particle size, solid/liquid ratio, and enzyme loadings. The amount of biosugars obtained after optimization was 26.15 ± 1.43 mg/g. To the best of our knowledge, this is the first report on optimization of agarase in D. arenaria .

The fucoidanase from Fusarium sp. (LD8) was obtained by solid-state fermentation. The fermented solid medium was extracted by citric acid buffer, and the extracts were precipitated by acetone and purified by Sephadex G-100 successively. The results showed that the specific fucoidanase activity of purified enzyme was 22.7-fold than that of the crude enzyme. The recovery of the enzyme was 23.9%. The purified enzyme gave a single band on SDS-PAGE gel, and the molecular weight of fucoidanase was about 64 kDa. The isoelectric point of the enzyme was 4.5. The enzyme properties were also studied. The results showed that the optimum temperature and pH were 60°C and 6.0, respectively; the temperature of half inactivation was 50°C, and the most stable pH for the enzyme was 6.0. KM, and the Vmax  of the enzyme was 8.9 mg·L−1 and 2.02 mg·min−1·mL−1 by using fucoidan from Fucus vesiculosus as substrate. The compositions of the secondary structure of fucoidanase were estimated by FTIR, the second derivative spectra, and the curve-fitting analysis of the amide I bands in their spectra. The results showed that β-sheet was the dominant component (58.6%) and α-helix was the least (12%); the content of β-turn and random coil were 15.39% and 14.5%, respectively.

The saprobic, cosmopolitan, marine fungi Dendryphiella arenaria and Dendryphiella salina, isolated from various plant and algal substrates from different geographical locations and climatic zones, were studied for their adaptations to the abiotic and biotic parameters commonly found in their natural marine habitats. All the tested strains of D. arenaria and D. salina grew optimally on culture media with added marine salts, at pH values between 6.5 and 8.0 and at an incubation temperature of 25°C. The D. arenaria strains had faster mean colony extension rates under all conditions of culture. All strains exhibited an increased salt optimum with increasing incubation temperature. The TLC profiles of strains of the two species were similar. The culture extracts were antimicrobial, though production of the biologically active metabolites was strain-specific. There were no significant correlations between source of origin and responses to the investigated parameters. These results demonstrate phenotypic plasticity and the ability of each isolate to adapt to diverse biotopes.[PUBLICATION ABSTRACT]

The deuteromycetes Dendryphiella arenaria and D. salina occur on macroalgae and plant debris in marine habitats. Strains from 17 locations in Canada, New England, the Southeast, Pacific Northwest and Europe were isolated from beaches and salt marshes or obtained from culture collections. The relationships between the species and the degree of genetic variability among different populations were studied. Starch-gel electrophoresis was used to analyze electromorph variation from 11 enzyme systems encoded by 14 presumptive structural loci. Strains of D. salina from different localities had identical electromorph patterns except for 3 strains isolated from Shelter Cove, California. All strains identified as D. arenaria differed from D. salina for four enzyme systems. Our data demonstrate that consistent genetic differences exist between the taxa and support the retention of two species. Some strains could not be placed with certainty in either species because of overlapping morphological characteristics; however, electrophoretic results indicate that all of these belonged to D. arenaria. The genetic variability observed was very low compared to other organisms including fungi. Our electrophoretic data indicate that both D. arenaria and D. salina are generalists and it is unlikely they have teleomorphs.

Abstract Carbon utilization by the marine Dendryphiella species, D. arenaria and D. salina, was investigated to detect differences in utilization and traits associated with their adaptation to the marine habitat. Fifty-four strains were isolated world-wide and tested for the utilization of various carbon sources using BIOLOG phenotype MicroArray (PM) and for the production of extracellular enzymes on solid culture media and on API ZYM assay strips. PM analysis showed that the fastest growth occurred on several monosaccharides and amino acids, 2-keto-d-gluconic acid, succinamide and turanose. Some polyols were poor carbon sources. However, the two species differed in their utilization rates of carbon sources, forming three major clusters: two separate clusters for D. arenaria and D. salina and a third cluster in which strains of the two species formed separate subclades that correlated with geographic origin. Several carbon sources were also found useful in differentiating the two speices. Dendryphiella salina did not utilize xylitol and quinic acid, whereas D. arenaria grew well on these substrates. The latter failed to grow on sorbitol and grew slowly on mannitol, both were good substrates for the former. There were also no qualitative differences between the extracellular enzymes produced, although laccase and peroxidase activities were confined only to some strains. The physiological similarities exhibited by the two species support the close relationship between D. arenaria and D. salina.