Os alimentos funcionais constituem hoje prioridade em pesquisas devido a crescente busca dos consumidores por alimentos que alÃm da funÃÃo bÃsica de nutrir possam trazer outros benefÃcios. Dessa forma, estudos para o desenvolvimento de prebiÃticos tornam-se interessantes. A enzima dextrana-sacarase quando em meio contendo sacarose e um aceptor como substrato produz oligossacarÃdeos prebiÃticos. O suco de caju funciona como fonte de aceptores, uma vez que à rico em glicose e frutose. A produÃÃo da enzima dextrana-sacarase pode ser realizada via processo fermentativo atravÃs da inoculaÃÃo da bactÃria Leuconostoc mesenteroides NRRL B512F ao meio de cultura contendo sacarose. Dessa forma o objetivo desse trabalho foi a produÃÃo de oligossacarÃdeos prebiÃticos via processo enzimÃtico com adiÃÃo da enzima dextranaâsacarase ao suco de caju clarificado. Com base nos resultados obtidos, pode-se concluir que o suco de caju clarificado pode ser empregado como uma alternativa de substrato de baixo custo para a sÃntese de oligossacarÃdeos prebiÃticos, por via enzimÃtica utilizando a enzima dextrana-sacarase. O rendimento em dextrana foi favorecido pela combinaÃÃo de baixas concentraÃÃes de sacarose e aÃÃcares redutores. A formaÃÃo de oligossacarÃdeos foi favorecida pelo aumento da concentraÃÃo dos aÃÃcares redutores e pela combinaÃÃo de elevadas concentraÃÃes de sacarose e aÃÃcares redutores. Neste trabalho a maior concentraÃÃo de oligossacarÃdeos obtida foi de 104,73 g/L utilizando-se 75 g/L de sacarose em combinaÃÃo com 75 g/L de aÃucares redutores e por fim a anÃlise qualitativa mostrou que em concentraÃÃes de 25 g/l e 75 g/l de sacarose e aÃÃcar redutor, respectivamente foi possÃvel obter oligossacarÃdeos de grau de polimerizaÃÃo atà 12. / Functional foods are now a research priority due to growing demand for foods that, besides the basic function of nurture, can bring benefits. Thus, studies for the development of prebiotics become interesting. The enzyme dextransucrase in a medium containing sucrose and an acceptor as substract synthesizes prebiotics oligosaccharides. The cashew apple juice works as a source of acceptors, since it is rich in glucose and fructose. The production of dextransucrase enzyme can be accomplished by fermentative process by inoculating the bacterium Leuconostoc mesenteroides NRRL B512F into a culture medium containing sucrose.Thus the aim of this work was the production of prebiotic oligosaccharides by enzymatic process with addition of the dextransucrase enzyme to the clarified cashew apple juice. Based on the results we can conclude that the clarified cashew apple juice can be used as low cost alternative substrate for the synthesis of prebiotic oligosaccharides through enzyme synthesis using the dextransucrase enzyme. Dextran yeld was favored by the combination of low concentrations of sucrose and reducing sugars. The formation of oligosaccharides was favored by increasing the concentration of reducing sugars and by the combination of high concentrations of sucrose and reducing sugars, where the largest concentration of oligosaccharides obtained was 104.73 g/L using 75g/L sucrose in combination with 75g/L of reducing sugars and finally the qualitative analysis shows that at concentrations of 25 g/L and 75g/L sucrose and reducing sugar, respectively, is possible to obtain oligosaccharides of degree of polymerization up to 12.

SILVA, Isabel Moreira da. Suco de caju contendo oligossacarídeos prébioticos. 2010. 61 f. : Dissertação (mestrado) - Universidade Federal do Ceará, Centro de Ciências Agrárias, Departamento de Tecnologia de Alimentos, Fortaleza-CE, 2010 / Submitted by Nádja Goes (nmoraissoares@gmail.com) on 2016-06-10T13:30:41Z No. of bitstreams: 1 2010_dis_imsilva.pdf: 509842 bytes, checksum: 99fe8ba547aa30fada3854402b582dfd (MD5) / Approved for entry into archive by Nádja Goes (nmoraissoares@gmail.com) on 2016-06-10T13:30:51Z (GMT) No. of bitstreams: 1 2010_dis_imsilva.pdf: 509842 bytes, checksum: 99fe8ba547aa30fada3854402b582dfd (MD5) / Made available in DSpace on 2016-06-10T13:30:51Z (GMT). No. of bitstreams: 1 2010_dis_imsilva.pdf: 509842 bytes, checksum: 99fe8ba547aa30fada3854402b582dfd (MD5) Previous issue date: 2010 / Functional foods are now a research priority due to growing demand for foods that, besides the basic function of nurture, can bring benefits. Thus, studies for the development of prebiotics become interesting. The enzyme dextransucrase in a medium containing sucrose and an acceptor as substract synthesizes prebiotics oligosaccharides. The cashew apple juice works as a source of acceptors, since it is rich in glucose and fructose. The production of dextransucrase enzyme can be accomplished by fermentative process by inoculating the bacterium Leuconostoc mesenteroides NRRL B512F into a culture medium containing sucrose.Thus the aim of this work was the production of prebiotic oligosaccharides by enzymatic process with addition of the dextransucrase enzyme to the clarified cashew apple juice. Based on the results we can conclude that the clarified cashew apple juice can be used as low cost alternative substrate for the synthesis of prebiotic oligosaccharides through enzyme synthesis using the dextransucrase enzyme. Dextran yeld was favored by the combination of low concentrations of sucrose and reducing sugars. The formation of oligosaccharides was favored by increasing the concentration of reducing sugars and by the combination of high concentrations of sucrose and reducing sugars, where the largest concentration of oligosaccharides obtained was 104.73 g/L using 75g/L sucrose in combination with 75g/L of reducing sugars and finally the qualitative analysis shows that at concentrations of 25 g/L and 75g/L sucrose and reducing sugar, respectively, is possible to obtain oligosaccharides of degree of polymerization up to 12. / Os alimentos funcionais constituem hoje prioridade em pesquisas devido a crescente busca dos consumidores por alimentos que além da função básica de nutrir possam trazer outros benefícios. Dessa forma, estudos para o desenvolvimento de prebióticos tornam-se interessantes. A enzima dextrana-sacarase quando em meio contendo sacarose e um aceptor como substrato produz oligossacarídeos prebióticos. O suco de caju funciona como fonte de aceptores, uma vez que é rico em glicose e frutose. A produção da enzima dextrana-sacarase pode ser realizada via processo fermentativo através da inoculação da bactéria Leuconostoc mesenteroides NRRL B512F ao meio de cultura contendo sacarose. Dessa forma o objetivo desse trabalho foi a produção de oligossacarídeos prebióticos via processo enzimático com adição da enzima dextrana–sacarase ao suco de caju clarificado. Com base nos resultados obtidos, pode-se concluir que o suco de caju clarificado pode ser empregado como uma alternativa de substrato de baixo custo para a síntese de oligossacarídeos prebióticos, por via enzimática utilizando a enzima dextrana-sacarase. O rendimento em dextrana foi favorecido pela combinação de baixas concentrações de sacarose e açúcares redutores. A formação de oligossacarídeos foi favorecida pelo aumento da concentração dos açúcares redutores e pela combinação de elevadas concentrações de sacarose e açúcares redutores. Neste trabalho a maior concentração de oligossacarídeos obtida foi de 104,73 g/L utilizando-se 75 g/L de sacarose em combinação com 75 g/L de açucares redutores e por fim a análise qualitativa mostrou que em concentrações de 25 g/l e 75 g/l de sacarose e açúcar redutor, respectivamente foi possível obter oligossacarídeos de grau de polimerização até 12.

RABELO, Maria Cristiane. Aproveitamento do pedúnculo do caju para síntese de oligossacarídeos prebióticos. 2008. 102 f. : Dissertação (mestrado) - Universidade Federal do Ceará, Departamento de Tecnologia de Alimentos, Curso de Mestrado em Ciências e Tecnologia de Alimentos, Fortaleza-CE, 2008 / Submitted by Nádja Goes (nmoraissoares@gmail.com) on 2016-06-17T15:45:41Z No. of bitstreams: 1 2008_dis_mcrabelo.pdf: 720591 bytes, checksum: 97be0059816995ce0d171844b7250e9c (MD5) / Approved for entry into archive by Nádja Goes (nmoraissoares@gmail.com) on 2016-06-17T15:45:56Z (GMT) No. of bitstreams: 1 2008_dis_mcrabelo.pdf: 720591 bytes, checksum: 97be0059816995ce0d171844b7250e9c (MD5) / Made available in DSpace on 2016-06-17T15:45:56Z (GMT). No. of bitstreams: 1 2008_dis_mcrabelo.pdf: 720591 bytes, checksum: 97be0059816995ce0d171844b7250e9c (MD5) Previous issue date: 2008 / Leuconostoc mesenteroides B742 produces the enzyme dextransucrose in a medium containing sucrose (carbon source), a nitrogen source and mineral salts. This enzyme catalyses dextran synthesis when the only carbon source is sucrose. When acceptors (maltose, fructose, glucose or other simple sugar) are present as the main substrate and sucrose is the second one, the enzyme synthesizes prebiotic oligosaccharides. These carbohydrates are not digested by humans and reach the large intestine where they are metabolized by bifidobacteria and lactobacilli, the intestine endogenous microbiota, increasing their growth. The most published papers about oligosaccharides synthesis using dextransucrase from Leuconostoc mesenteroides are related to the strain B512F and the synthesis is carried out using synthetic substrates. The cashew tree, largely grown in Ceará state, has a peduncle (pseudofruit) which is wasted. Considering that the peduncle corresponds to 90 % of the fruit weight, its annual estimated production is about 1,5 millions tons. However, only 5% of this production is industrially used or consumed in natura, being large amounts wasted in the field. This work aimed to the study of the prebiotic oligosaccharide synthesis through the acceptor reaction with dextransucrase enzyme from Leuconostoc mesenteroides B742 in natura clarified cashew apple juice. The partial substitution of yeast extract by ammonium sulfate as nitrogen source was also investigated. According to the results obtained, the clarified cashew apple juice can be used as low cost alternative substrate to grow L.mesenteroides B742 and to produce prebiotic oligosaccharide through enzyme synthesis. The crude enzyme showed higher stability in the clarified cashew apple juice when compared to the synthetic medium, making this substrate interesting for industrial applications because enzyme purification protocols are one of the most expensive steps in enzyme process. The partial substitution of yeast extract by ammonium sulfate also showed technical viability without enzyme yield losses. / O Leuconostoc mesenteroides B742 produz a enzima dextrana-sacarase em meio sintético contendo sacarose (fonte de carbono), fonte de nitrogênio e sais. Esta enzima catalisa a formação de dextrana quando em meio contendo acarose como único substrato. Entretanto, quando em meio contendo um aceptor (maltose, frutose, glicose ou outro açúcar simples) como substrato predominante e sacarose como segundo substrato, a enzima produz oligossacarídeos prébióticos. Estes carboidratos não são digeridos por humanos e ao chegarem no intestino grosso são metabolizados pelas bifidobactérias e lactobacilos, ali presentes, estimulando o seu crescimento. A maioria dos trabalhos publicados sobre a síntese de oligosscarídeos com dextrana-sacarase de Leuconostoc mesenteroides são relativos à linhagem B512F e utilizam substratos sintéticos. O caju, largamente cultivado no Ceará, possui castanha (verdadeiro fruto) e pedúnculo (pseudofruto) que é fonte de vitamina C. Considerando-se que o pedúnculo corresponde a 90% do peso do caju, calcula-se que o país produza cerca de 1,5 milhão de toneladas desse produto. No entanto, apenas 5% desse total é aproveitado industrialmente ou para consumo in natura, sendo grande parte perdida no campo. Dessa forma, o presente trabalho teve como objetivo o aproveitamento do pedúnculo como substrato para a síntese de oligossacarídeos prebióticos pela reação do aceptor com a enzima dextranasacarase, obtida via processo fermentativo a partir do Leuconostoc mesenteroides B742 no suco de caju clarificado in natura. A substituição parcial do extrato de levedura por sulfato de amônio como fonte de nitrogênio foi também avaliada. Com base nos resultados obtidos pode-se concluir que o suco de caju clarificado pode ser empregado como uma alternativa de substrato de baixo custo para o crescimento do Leuconostoc mesenteroides B742 e para a produção de oligossacarídeos prebióticos via síntese enzimática. A enzima bruta apresentou estabilidade superior no suco de caju quando comparada ao meio sintético, tornando este substrato bastante interessante do ponto de vista industrial, uma vez que a purificação da enzima é uma das etapas mais caras em processos enzimáticos. A substituição parcial do extrato de levedura por sulfato de amônio na produção da enzima se mostrou eficaz não causando perdas na produção da enzima.

CoordenaÃÃo de AperfeiÃoamento de NÃvel Superior / O Leuconostoc mesenteroides B742 produz a enzima dextrana-sacarase em meio sintÃtico contendo sacarose (fonte de carbono), fonte de nitrogÃnio e sais. Esta enzima catalisa a formaÃÃo de dextrana quando em meio contendo acarose como Ãnico substrato. Entretanto, quando em meio contendo um aceptor (maltose, frutose, glicose ou outro aÃÃcar simples) como substrato predominante e sacarose como segundo substrato, a enzima produz oligossacarÃdeos prÃbiÃticos. Estes carboidratos nÃo sÃo digeridos por humanos e ao chegarem no intestino grosso sÃo metabolizados pelas bifidobactÃrias e lactobacilos, ali presentes, estimulando o seu crescimento. A maioria dos trabalhos publicados sobre a sÃntese de oligosscarÃdeos com dextrana-sacarase de Leuconostoc mesenteroides sÃo relativos à linhagem B512F e utilizam substratos sintÃticos. O caju, largamente cultivado no CearÃ, possui castanha (verdadeiro fruto) e pedÃnculo (pseudofruto) que à fonte de vitamina C. Considerando-se que o pedÃnculo corresponde a 90% do peso do caju, calcula-se que o paÃs produza cerca de 1,5 milhÃo de toneladas desse produto. No entanto, apenas 5% desse total à aproveitado industrialmente ou para consumo in natura, sendo grande parte perdida no campo. Dessa forma, o presente trabalho teve como objetivo o aproveitamento do pedÃnculo como substrato para a sÃntese de oligossacarÃdeos prebiÃticos pela reaÃÃo do aceptor com a enzima dextranasacarase, obtida via processo fermentativo a partir do Leuconostoc mesenteroides B742 no suco de caju clarificado in natura. A substituiÃÃo parcial do extrato de levedura por sulfato de amÃnio como fonte de nitrogÃnio foi tambÃm avaliada. Com base nos resultados obtidos pode-se concluir que o suco de caju clarificado pode ser empregado como uma alternativa de substrato de baixo custo para o crescimento do Leuconostoc mesenteroides B742 e para a produÃÃo de oligossacarÃdeos prebiÃticos via sÃntese enzimÃtica. A enzima bruta apresentou estabilidade superior no suco de caju quando comparada ao meio sintÃtico, tornando este substrato bastante interessante do ponto de vista industrial, uma vez que a purificaÃÃo da enzima à uma das etapas mais caras em processos enzimÃticos. A substituiÃÃo parcial do extrato de levedura por sulfato de amÃnio na produÃÃo da enzima se mostrou eficaz nÃo causando perdas na produÃÃo da enzima. / Leuconostoc mesenteroides B742 produces the enzyme dextransucrose in a medium containing sucrose (carbon source), a nitrogen source and mineral salts. This enzyme catalyses dextran synthesis when the only carbon source is sucrose. When acceptors (maltose, fructose, glucose or other simple sugar) are present as the main substrate and sucrose is the second one, the enzyme synthesizes prebiotic oligosaccharides. These carbohydrates are not digested by humans and reach the large intestine where they are metabolized by bifidobacteria and lactobacilli, the intestine endogenous microbiota, increasing their growth. The most published papers about oligosaccharides synthesis using dextransucrase from Leuconostoc mesenteroides are related to the strain B512F and the synthesis is carried out using synthetic substrates. The cashew tree, largely grown in Cearà state, has a peduncle (pseudofruit) which is wasted. Considering that the peduncle corresponds to 90 % of the fruit weight, its annual estimated production is about 1,5 millions tons. However, only 5% of this production is industrially used or consumed in natura, being large amounts wasted in the field. This work aimed to the study of the prebiotic oligosaccharide synthesis through the acceptor reaction with dextransucrase enzyme from Leuconostoc mesenteroides B742 in natura clarified cashew apple juice. The partial substitution of yeast extract by ammonium sulfate as nitrogen source was also investigated. According to the results obtained, the clarified cashew apple juice can be used as low cost alternative substrate to grow L.mesenteroides B742 and to produce prebiotic oligosaccharide through enzyme synthesis. The crude enzyme showed higher stability in the clarified cashew apple juice when compared to the synthetic medium, making this substrate interesting for industrial applications because enzyme purification protocols are one of the most expensive steps in enzyme process. The partial substitution of yeast extract by ammonium sulfate also showed technical viability without enzyme yield losses.

"Bacteria during the course of their life undergo a lot of developments on their surface. The changes that occur inside a cell result in the production of a variety of biopolymers on the cell surface. These polysaccharides have been found to play a major role in deciding the adhesive or repulsive nature of a bacterial cell. Based on the application the adhesive nature of a cell sometimes needs to be manipulated such that bacteria are required to have higher adhesions for bioremediation applications and in the case of bioreactors bacteria must not stick to walls to avoid fouling. In order to control adhesions of a cell to a variety of substrates, knowledge of the polysaccharides present on its surface is needed. Therefore the goal of the present study is to detect the sugars present on the surface of Pseudomonas putida KT2442 using Atomic force microscopy and to relate properties of the polysaccharides to bacterial adhesion. Previous experiments suggested that cellulose and other sugars were produced by Pseudomonas putida KT2442. Thus the cells were grown to late exponential phase and treated with cellulase to degrade any cellulose, if present, on the surface of the cells. Control experiments were done on untreated cells and cells that were not treated with cellulase but were centrifuged, since centrifugation is a part of the cellulase treatment and may also affect the bacterial surface. An appropriate (Steric) fitting model for the atomic force microscope (AFM) approach curves was applied to calculate the height and density of the polymer brush layer present on the cell surface. There was a decrease in the density of the polymer brush and increase in the height of the brush upon treatment with cellulase. Centrifugation alone did not affect the approach curves. From looking at the retraction curves it verified the results got from the approach curves and indicated stretching out of the polymer brush to greater distances after the treatment with cellulase. Another batch of cells was treated with dextranase to check for the presence of dextran on the cell surface. Dextranase treated cells behaved identical to the control cells, suggesting that dextran is not one of the polysaccharides present on the bacterial surface. No change was observed in retraction curves data for dextranase treated and untreated cells."

Orientador: Jonas Contiero / Banca: Clóvis Parazzi / Banca: Luiz Carlos Basso / Banca: Pedro de Oliva Neto / Banca: Cíntia Duarte de Freitas Milagre / Resumo: O objetivo deste trabalho foi isolar micro-organismos produtores de D-(-) e L-(+) ácido lático, os quais são utilizados na síntese de polímeros empregados na produção de diversos materiais resistentes e biodegradáveis, além de otimizar a produção de ácido lático, a partir da utilização de diversos resíduos agro-industriais. Os micro-organismos mais promissores para produção de L-(+) ácido lático foram os isolados de Keffir (Ke6, Ke11, Ke8 e Ke24) e o Lactobacillus rhamnosus B103, já para a produção de D-(-) ácido lático, os mais promissores foram os isolados de iogurte (Y15C e Y15A) e o Leuconostoc mesenteroides B512. Pode-se afirmar que os micro-organismos selecionados apresentaram grande potencial para utilização na indústria de biopolímeros e indústria de alimentos. O soro de queijo e a manipueira foram os melhores resíduos para produção de L-(+) ácido lático por Lactobacillus rhamnosus B103. Quando se utilizou 160 g/L de lactose de soro de queijo, 60 mL/L de água de maceração de milho (AMM), 2 mL/L de Tween 80 e 0,10 g/L de MnSO4, observou-se alta produção de L- (+) ácido lático (142 g/L) e baixo residual de lactose (3,2 g/L). Para a otimização com manipueira, foi obtido 41,58 g/L de L-(+) ácido lático, a partir de 50 g/L de açúcar redutor total (ART), 65,40 mL/L de AMM e 1,27 mL/L de Tween 80. Nas otimizações com Leuconostoc mesenteroides B512 foi observado produção de 60,20 g/L de D-(-) ácido lático, utilizando 116,90 g/L de ART de caldo de cana e 44,25 g/L de autolisado de levedura. Nas otimizações com L. plantarum Lmism6 observou-se uma produção de 63,40 g/L de ácido lático, 0,40 g/L de ART residual e alta conversão de substrato (99,40%), quando se utilizou 70 g/L de ART de melaço, 30,00 mL/L de AMM, 2 g/L de K2HPO4 e 1 mL/L de Tween 80 / Abstract: The aim of this study was to isolate D-(-) and L-(+) lactic acid producers micro-organisms, which are used in the synthesis of polymers used in the production of many resistant and biodegradable materials and optimize the lactic acid production, from agro-industrial residues. The most promising micro-organisms for L-(+) lactic acid production were Lactobacillus rhamnosus B103, as well as, the isolated from Keffir (Ke6, Ke11, Ke8 Ke24) and the most promising D-(-) lactic acid producers were strains of yogurt (Y15C and Y15A) and Leuconostoc mesenteroides B512. Cheese whey and cassava wastewater (CW) were the best residues for L-(+) lactic acid production by Lactobacillus rhamnosus B103. Using 160 g/L of lactose from whey, 60 mL/L of CSL, 2 mL/L of Tween 80 and 0.10 g/L of MnSO4, there was higher production of L-(+) lactic acid (142 g/L) and low lactose residual (3.20 g/L). For optimizations with CW, it was obtained 41.58 g/L of L-(+) lactic acid from 50 g/L of reducing sugar, 65.40 mL/L and 1.27 mL of corn steep liquor (CSL) and Tween 80 respectively. Leuconostoc mesenteroides B512 produced 60.20 g/L of D-(-) lactic acid, using 116.90 g/L of sugarcane juice and 44.25 g/L of yeast autolysate. L. plantarum Lmism6 produced 63.40 g/L of lactic acid, with less residual reducing sugar (0.41 g/L) and higher substrate conversion (99.41%), by using 70 g/L of sugar reducing from molasses, 30 mL/L of CSL, 2 g/L of K2HPO4, and 1 mL/L of Tween 80 / Doutor

Bacteriocin leader pepides are currently receiving much attention due to their possible functions. It is predicted that these leaders prevent cytoplasmic toxicity within the producer organism by rendering the bacteriocin inactive. Leucocin A, a class IIa bacteriocin produced by Leuconostoc gelidum UAL187-22 is synthesized with a 24 amino acid leader pepide which is cleaved during extracellular translocation. The antimicrobial activity of the leucocin A precursor, pre-leucocin A, was determined to gain insight into whether, the presence of a leader peptide has an impact on anti-listerial activity. The leucocin A and pre-leucocin A genes were generated by PCR of L. gelidum UAL187-22 plasmid DNA. Recombinant plasmids, pLcaA and pPreLcaA were isolated by cloning the amplified genes into the Escherichia coli pMAL.c2 vector, and by screening transformant colonies using blue white selection methods. The malE-LcaA and malE-preLcaA fusion genes were expressed, and resulting maltose binding fusion proteins, were purified using amylose affinity chromatography. Fractions collected, contained partially pure forms of MBP-LcaA (46.433 kDa) and MBP-preLcaA (49.088 kDa) fusion proteins. Following Factor Xa digestion, the MBP affinity tag was removed; and recombinant peptides, leucocin A and pre-leucocin A were further purified by reverese phase high performance liquid chromatography. It was determined that leucocin A was eluted with a retention time of 24.893, while pre-leucocin A was eluted with a retention time of 31.447. Fractions of pure leucocin A and pre-leucocin A were thereafter assayed for activity using a deferred antagonism assay, with Listeria monocytogenes being the indicator strain. Pre-leucocin A tested positive for antimicrobial activity. However, when compared to leucocin A it was found that the leucocin A precursor inhibits Listeria to a lesser degree than leucocin A. The relative bactericidal activities of leucocin A and pre-leucocin A was calculated at 6.0 x 10⁵ AU and 4.0 x 10⁵ AU. Taking this into consideration, it was estimated that the leucocin A precursor is ~66.667 % active as mature leucocin A. Hence the presence of a leader peptide does not have an influence on leucocin A antimicrobial activity. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.

Post-harvest cane deterioration in the South African sugar industry results in significant revenue loss that is estimated to be in the region of ZAR 60 million per annum. Despite these large losses, precise biological data relating to the process of cane deterioration under South African conditions is limited. Severity of deterioration is influenced by a number of factors, including the length of the harvest-to-crush delay (HTCD), ambient temperature and harvesting practices. For example, burning of cane prior to harvest may result in rind splitting, which provides entry for microbes, particularly Leuconostoc mesenteroides that may exacerbate deterioration. The effect of these factors on deterioration was examined by quantifying the biochemical and microbiological changes that occur in sugarcane stalks after harvest, with the influence of length of HTCD, degree of L. mesenteroides infection and ambient temperature receiving attention. The primary novelty of the work resides in the analysis of deterioration under tightly regulated temperatures, which were designed to reflect diurnal variations typically experienced during summer and winter in the South African sugar belt. In addition, inoculation of mature internodes with a consistent titre of L. mesenteroides was used as a means to mimic a consistent level of infection of harvested stalks by the bacterium. Metabolites selected for analysis were those both native to the stalk and produced as by-products of microbial metabolism, viz. sucrose, glucose, fructose, ethanol, lactic acid, dextran and mannitol. Simulated HTCDs under summer temperatures resulted in increasing glucose and fructose levels with time, which contrasted to the approximately constant levels of these hexose sugars under winter conditions. Commonly referred to as ‘purity’ in an industrial context, precise determination of the concentration of these hexoses in cane consignments could potentially indicate the extent of deterioration. Despite the detection of a basal concentration of lactic acid in unspoiled cane, the observed increase in concentration of this organic acid over the simulated summer HTCD suggests that this metabolite could also potentially serve as an indicator for postharvest deterioration. In contrast, the investigation indicated that ethanol was an unsuitable biochemical marker for deterioration of L. mesenteroides infected cane. An inability to detect dextran and mannitol in the samples, combined with consistent sucrose levels and variable mill room data, suggest that extreme proliferation of L. mesenteroides is facilitated primarily by in-field practices, particularly the manner in which cane is prepared prior to harvest and transport to the mill. Bacterial proliferation and infection by L. mesenteroides of inoculated stalks were monitored by standard selective culturing techniques. Despite the limited detection of L. mesenteroides-associated metabolites, culture-based analyses revealed that the bacterium was the dominant bacterial species within the samples. A number of other bacterial species were isolated and identified, however the extent to which the total number of microorganisms proliferated was limited to a maximum of 1 x 105 colony forming units per gram of fresh tissue. In conjunction with these analyses, a molecular approach known as Polymerase Chain Reaction-Mediated Denaturing Gradient Gel Electrophoresis (PCR-DGGE) was undertaken to investigate the bacterial diversity patterns associated with deteriorating sugarcane stalks throughout the delay period. In contrast to the results obtained by means of the culture-based assays, PCR-DGGE revealed that L. mesenteroides was not the dominant bacterial population, and showed that the level of bacterial diversity was relatively consistent across the differing treatments and with time. The use of complimentary culture-dependent and cultureindependent analyses thus permitted the detection of this discrepancy and indicated the utility of PCR-DGGE in the determination of bacterial community structure of postharvest sugarcane tissue. The biology of post-harvest deterioration of green sugarcane stalks is highly complex, even under rigorously controlled temperature and infection regimens. The results of this study emphasize the important effects that harvest method and environmental conditions have on post-harvest sugarcane deterioration. Towards the formulation of industry-relevant recommendations for combating post-harvest deterioration, future work will strive to mimic the effects that harsh harvesting and transport practices have on the severity of the problem. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.

Diss. (sammanfattning) Alnarp : Sveriges lantbruksuniversitet, 2004. / Härtill 5 uppsatser.

Submitted by Caroline Falcao (caroline.rfalcao@ufpe.br) on 2017-04-06T18:40:10Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) 2012-Dissertação-BillySantos.pdf: 1715330 bytes, checksum: 928f73e06e0a832aee3a63d319146b43 (MD5) / Made available in DSpace on 2017-04-06T18:40:10Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) 2012-Dissertação-BillySantos.pdf: 1715330 bytes, checksum: 928f73e06e0a832aee3a63d319146b43 (MD5) Previous issue date: 2012 / A indústria alcooleira no Brasil perde anualmente vários milhares de reais devido a episódios de contaminação produzidos por bactérias. Além disso, outros milhares são gastos com o uso de antibióticos industriais para a contenção dessas contaminações. Infelizmente, não há ainda um catálogo completo de informações sobre todas as possíveis espécies bacterianas envolvidas na contaminação industrial, seus efeitos no processo e os fatores que levam a essas contaminações. Com a crescente demanda por fontes de energia renováveis, principalmente o etanol, grandes esforços têm sido feitos para aumentar a sua produção. Este trabalho tem como objetivo principal identificar as bactérias lácticas que entram no processo de fermentação alcoólica através do caldo de cana-de-açúcar com a utilização de ferramentas moleculares para uma rápida e eficiente identificação. Para foram realizadas coletas em quatro destilarias do Nordeste do Brasil durante a safra de 2007/2008. A identificação dos isolados foi realizada através da técnica ARDRA e pela análise do sequenciamento de DNA dos genes pheS e 16S. Os resultados obtidos mostram que os lactobacilos são os principais contaminantes do processo, com o Lactobacillus fermentumse destacando entre as demais. Também foi observado que entram no processo bactérias dos gene Weissella eLeuconostoc, com destaque para a W. confusa e o Leuc. mesenteroides que foram identificadas em três das destilarias estudadas. Além da identificação, os isolados de W. confusa e o Leuc. Mesenteroidesforam tipados pelo REP-PCR com o primer(GTG)5. Os resultados mostraram que, além da diversidade de espécies bacterianas detectadas, existe uma diversidade de linhagens dessas duas principais espécies no processo. A espécie Leuc. mesenteroides tem sido apontada como contaminante em processo de fermentação alcoólica industrial, sendo algumas linhagens capazes de causar a formação de dextrana, podendo causar danos ao processo fermentativo. Desta forma se faz necessário trabalhos futuros com o fim de correlacionar os perfis destas espécies com possíveis danos à fermentação, para que com este conhecimento possa ser criadas novas estratégias de controle destes microorganismos. / The alcohol industry in Brazil loses several thousand dollars each year due to episodes of contamination produced by bacteria. In addition, thousands more are spent on the industrial use of antibiotics to contain these contaminants. Unfortunately, there is still no complete catalog of all possible information about bacterial species involved in industrial pollution, its effects on the process and the factors that lead to these contaminants. With the growing demand for renewable energy sources, especially ethanol, great efforts have been made to increase production. This work has as main objective to identify lactic acid bacteria that enter the process of fermentation through thejuicesugarcane with the use of molecular tools for rapid and efficient identification. For this, samples were taken at four distilleries in northeastern Brazil during the harvest of 2007/2008. The identification of isolates was performed using the ARDRA technique and analysis of DNA sequencing of the pheSand 16S genes. The results show that lactobacilli are the main contaminants of the process with Lactobacillus fermentumstood out among the others. We also observed that bacteria enter the process of genus Weissellaand Leuconostoc, with emphasis on the W. confusedand Leuc. mesenteroidesthat were identified in three distilleries studied. Besides identification, the isolates of W. confusaand Leuc. mesenteroideswere typed by rep-PCR with the primer (GTG)5. The results showed that, in addition to the variety of bacterial species found, there are several lines of these two major species in the process. The species Leuc. mesenteroideshas been identified as a contaminant in industrial fermentation process, some strains can cause the formation of dextran, causing damage to the process. Thus further work is required in order to correlate the profiles of these species with possible damage to the fermentation, so that this knowledge can be created new control strategies such microorganisms.