Bioprospecting of enzymes from marine bacteria and fungi from untapped deep-sea extreme habitats is the main aim of this work, with special reference to ketoreductases, esterases, fructofuranosidases, and transaminases. These enzymes have been used as free enzymes or still bound to whole cells for performing selective biotransformations in conventional aqueous media or in seawater. Marine bacteria and fungi were screened for enzymes with potential as biocatalysts. Cultures were grown in media with increasing NaCl concentrations (0-10%) for simultaneously testing growth and enzymatic profiles. Four enzymatic activities were screened: carboxylesterases (EST), omega-transaminases (omega-TA), ketoreductases (KRED), and fructofuranosidases (FF). A screening among bacterial strains was carried out for the resolution of racemic propyl ester of anti-2-oxotricyclo[188.8.131.52]heptan-7-carboxylic acid 1, a key intermediate for the synthesis of D-cloprostenol. Bacillus horneckiae 15A gave highly stereoselective reduction of (R,S)-1, whereas Halomonas aquamarina 9B enantioselectively hydrolysed (R,S)-1; in both cases, enantiomerically pure unreacted (R)-1 could be easily recovered and purified at molar conversion below 57– 58 %, showing the potential of marine-derived enzymes in stereoselective biocatalysis. A strain of Virgibacillus pantotheticus (21D) showed optimal growth and activity in the presence up to 10% NaCl concentration, showing both enantioselective esterase and ketoreductase activity. This strain showed also high omega-transaminase activity and its genome was sequenced. Three enzymes (KRED1-Vpan, EST1-Vpan and TAM1-Vpan) were produced as recombinant proteins in E. coli and are currently used for evaluating their potential as biocatalysts. Marine yeasts from UBO were used for evaluating KRED activities. In this case, we used a seawater-based marine medium for the growth and resting cells for the stereoselective reduction of 6 substrates, two of them are key-intermediates for chemoenzymatic synthesis of pharma ingredients (pramipexole and levogestrel). The best results were achieved with a strain of Meyerozyma guilliermondii and one of Rhodotorula mucilaginosa, which gave complementary and good enantioselectivity. Interestingly, these strains can be used in seawater also for the bioconversion. Finally, yeasts were used for fructooligosaccharides (FOS) production from sucrose (fructofuranosidases activity). No significant results could be observed, even if different conditions were applied. The screening was extended to other newly isolated halophilic fungi; a strain of Cladosporium cladosporioides resulted an efficient producer of fructooligosaccharides (FOS) from sucrose, giving mainly 1-kestose, 1-nystose, 1 F-fructosylnystose, 6-kestose, neokestose, and also blastose, an unconventional disaccharide. Lyophilized mycelium of C. cladosporioides grown in a seawater-based medium produced 344 g/L (57% w/w) of total FOS from 600g/L of sucrose in seawater under optimized conditions after 72h. Most of the bioprocesses studied were entirely accomplished in seawater.
Seawater-based Biocatalytic strategies using marine microorganisms / Benedetta Guidi, Patrizia Ferraboschi, Francesco Enzo Molinari, Immacolata Serra, Martina Letizia Contente, Valerio De Vitis, Diego Romano. ((Intervento presentato al convegno Creative Science and Processes for Biocatalysis tenutosi a Biddeford nel 2016.
|Titolo:||Seawater-based Biocatalytic strategies using marine microorganisms|
GUIDI, BENEDETTA (Primo)
FERRABOSCHI, PATRIZIA (Secondo)
|Data di pubblicazione:||12-lug-2016|
|Parole Chiave:||seawater; halotollarance; biotransformations; fructofuranosidases; marine bacteria; marine yeast; D-cloprostenol; pramipexole; levogestrel|
|Settore Scientifico Disciplinare:||Settore CHIM/11 - Chimica e Biotecnologia delle Fermentazioni|
|Citazione:||Seawater-based Biocatalytic strategies using marine microorganisms / Benedetta Guidi, Patrizia Ferraboschi, Francesco Enzo Molinari, Immacolata Serra, Martina Letizia Contente, Valerio De Vitis, Diego Romano. ((Intervento presentato al convegno Creative Science and Processes for Biocatalysis tenutosi a Biddeford nel 2016.|
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