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Previous issue date: 2015-03-31 === Biosurfactants are metabolites that contain both hydrophobic and hydrophilic
domains and are produced by various microorganisms. Due to its characteristics such
molecules localize preferable in the interface of polar and non-polar solvents.
Biosurfactants are widely used in pharmaceutic, cosmetic, food and agriculture
industries. Moreover, they are considered advantageous when compared to chemical
ones because they are biodegradable and non-toxic. Currently one of the best known
biosurfactant is the rhamnolipids. However, their utilization in large scale are still not
possible due to its high production costs. Rhamnolipids are produced mainly by
Pseudomonas aeruginosa and are composed by one or two molecules of L-rhamnose
attached to a fatty acid molecule. This study aimed the construction of yeast expression
vectors that will be used to construct a recombinant strain of Saccharomyces cerevisiae
efficient in the production of L-rhamnose and mono-rhamnolipid using sucrose as
substrate. For the construction of these vectors, six different genes, responsible for
encoding both L-rhamnose and mono-ramnolipideos biosynthetic pathways enzymes
described in P. aeruginosa (rmlA, rmlB, rmlC, rmlD, rhlA and rhlB), and one gene,
responsible for the synthesis of a substrate break enzyme, described in Pelomonas
sacchraphyla (sucrose phosphorylase) were utilized. The genetic engineering proposed
in this study is innovative, and has never been done before. The production of
rhamnolipid in large-scale at low costs will be highly beneficial for the development of
national technologies for production of high value-added chemical. === Biossurfactantes s??o metab??litos produzidos por diversos microrganismos. Estes
cont??m um dom??nio hidrof??lico e outro hidrof??bico, estando preferencialmente na
interface de compostos polares e apolares. Devido ??s suas propriedades, os
biosurfactantes s??o capazes de reduzir a tens??o de superf??cies tendo uma ampla
aplica????o na ind??stria farmac??utica, cosm??tica, aliment??cia e agr??cola. O uso de
biossurfactante em compara????o com os de origem qu??mica s??o considerados vantajosos,
uma vez que s??o biodegrad??veis e n??o t??xicos. Atualmente um dos biossurfactantes
mais conhecido e dispon??vel comercialmente s??o os ramnolip??deos. No entanto, a
utiliza????o destas mol??culas em larga escala ?? prejudicada devido aos seus elevados
custos de produ????o. Ramnolip??deos s??o produzidos principalmente por Pseudomonas
aeruginosa e s??o constitu??dos por uma ou duas mol??culas de L-ramnose ligada a uma
mol??cula de ??cido graxo. Assim, este estudo teve como objetivo a constru????o de
vetores de express??o em levedura para posterior constru????o de cepas recombinantes de
Saccharomyces cerevisiae visando a eficiente produ????o de L-ramnose e monoramnolip??deo
a partir de sacarose. Para a constru????o desses vetores, foram utilizados
seis genes, que codificam as enzimas respons??veis pelas vias de bioss??ntese de Lramnose
e mono-ramnolipideos descritos em P. aeruginosa (rmlA, rmlB, rmlC, rmlD,
rhlA e rhlB), e um gene, respons??vel pela s??ntese da enzima de quebra do substrato,
descrito em Pelomonas sacchraphyla (sacarose fosforilase). A engenharia gen??tica
proposta neste estudo ?? inovadora, e pela primeira vez realizada. Com a produ????o do
ramnolip??deo em larga escala ?? um baixo custo de produ????o, beneficiar?? o
desenvolvimento de tecnologias nacionais para produ????o de qu??micos de alto valor
agregado.
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