Bioprospecting of yeasts for amylase production in solid state fermentation and evaluation of the catalytic properties of enzymatic extracts

Profiling microorganisms with potential for amylase production in low cost culture media has been widely recognized due to its broad applicability. The aim of this study was to select yeast strains with potential to produce amylolytic enzymes by solid state fermentation. Fifty-four (54) strains were assessed and three exhibited ability to produce amylases: Candida parapsilosis with 14.68 U/mL (146.8 U/g substrate); Rhodotorula mucilaginosa with 25.0 U/mL (250 U/g substrate), and Candida glabrata with 25.39 U/mL (253.9 U/g substrate), in solid state fermentation, for 120 h at 28°C, using wheat bran with 70% moisture. The enzymes exhibited maximum activity at a pH of 7.0 and at 60°C. Amylases demonstrated satisfactory structural stability, maintaining their catalytic activity after 1 h at 50°C. All enzymes were ethanol tolerant and retained more than 70% of their original activities in 15% ethanol solution. Corn starch was efficiently hydrolyzed by enzymes and the extracts produced by C. parapsilosis and C. glabrata exhibited dextrinizing activity, while those produced by R. mucilaginosa exhibited saccharifying activity. Key words: Candida parapsilosis, Candida glabrata, Rhodotorula mucilaginosa, dextrinizing and saccharifying activit

Three-dimensional holographic optical manipulation through a high-numerical-aperture soft-glass multimode fibre

Holographic optical tweezers (HOT) hold great promise for many applications in biophotonics, allowing the creation and measurement of minuscule forces on biomolecules, molecular motors and cells. Geometries used in HOT currently rely on bulk optics, and their exploitation in vivo is compromised by the optically turbid nature of tissues. We present an alternative HOT approach in which multiple three-dimensional (3D) traps are introduced through a high-numerical-aperture multimode optical fibre, thus enabling an equally versatile means of manipulation through channels having cross-section comparable to the size of a single cell. Our work demonstrates real-time manipulation of 3D arrangements of micro-objects, as well as manipulation inside otherwise inaccessible cavities. We show that the traps can be formed over fibre lengths exceeding 100 mm and positioned with nanometric resolution. The results provide the basis for holographic manipulation and other high-numerical-aperture techniques, including advanced microscopy, through single-core-fibre endoscopes deep inside living tissues and other complex environments

Screening and Production Study of Microbial Xylanase Producers from Brazilian Cerrado

Hemicelluloses are polysaccharides of low molecular weight containing 100 to 200 glycosidic residues. In plants, the xylans or the hemicelluloses are situated between the lignin and the collection of cellulose fibers underneath. The xylan is the most common hemicellulosic polysaccharide in cell walls of land plants, comprising a backbone of xylose residues linked by beta-1,4-glycosidic bonds. So, xylanolytic enzymes from microorganism have attracted a great deal of attention in the last decade, particularly because of their biotechnological characteristics in various industrial processes, related to food, feed, ethanol, pulp, and paper industries. A microbial screening of xylanase producer was carried out in Brazilian Cerrado area in Selviria city, Mato Grosso do Sul State, Brazil. About 50 bacterial strains and 15 fungal strains were isolated from soil sample at 35 A degrees C. Between these isolated microorganisms, a bacterium Lysinibacillus sp. and a fungus Neosartorya spinosa as good xylanase producers were identified. Based on identification processes, Lysinibacillus sp. is a new species and the xylanase production by this bacterial genus was not reported yet. Similarly, it has not reported about xylanase production from N. spinosa. The bacterial strain P5B1 identified as Lysinibacillus sp. was cultivated on submerged fermentation using as substrate xylan, wheat bran, corn straw, corncob, and sugar cane bagasse. Corn straw and wheat bran show a good xylanase activity after 72 h of fermentation. A fungus identified as N. spinosa (strain P2D16) was cultivated on solid-state fermentation using as substrate source wheat bran, wheat bran plus sawdust, corn straw, corncob, cassava bran, and sugar cane bagasse. Wheat bran and corncobs show the better xylanase production after 72 h of fermentation. Both crude xylanases were characterized and a bacterial xylanase shows optimum pH for enzyme activity at 6.0, whereas a fungal xylanase has optimum pH at 5.0-5.5. They were stable in the pH range 5.0-10.0 and 5.5-8.5 for bacterial and fungal xylanase, respectively. The optimum temperatures were 55C and 60 A degrees C for bacterial and fungal xylanase, respectively, and they were thermally stable up to 50 A degrees C.16141852333346Fundação para o Desenvolvimento da UNESP (FUNDUNESP