Development of a multifunctional and self-preserving cosmetic formulation using sophorolipids and palmarosa essential oil against acne-causing bacteria.

AIMS: The objective of this study was to evaluate the antibacterial effect of sophorolipids in combination with palmarosa essential oil and to develop a cosmetic formulation against acne-causing bacteria. METHODS AND RESULTS: The antibacterial activity of sophorolipids, palmarosa oil and their combined effect was evaluated by broth microdilution and checkerboard methods. Antioxidant activity was determined by the DPPH method. The results showed that the compounds presented antibacterial activity against Staphylococcus aureus and Staphylococcus epidermidis. The combination of sophorolipid and palmarosa oil resulted in synergistic and additive interaction reducing the concentration needed for the effectiveness against S. aureus and S. epidermidis, to 98.4% and 50%, respectively. The compounds interaction showed an additive effect for antioxidant activity. The cosmetic formulation without any chemical preservative presents antibacterial activity against S. aureus, S. epidermidis and Cutibacterium acnes. The pH values and organoleptic characteristics of formulations remained stable under all conditions tested. CONCLUSIONS: The association of sophorolipids and palmarosa oil resulted in a self-preserving cosmetic formulation with great stability, and effective antioxidant and antibacterial activities against acne-causing micro-organisms. SIGNIFICANCE AND IMPACT OF THE STUDY: This study showed the development of an effective multifunctional cosmetic formulation with natural preservatives to treat acne vulgaris and other skin infections.

Antimicrobial effects of sophorolipid in combination with lactic acid against poultry-relevant isolates.

The objective of this study was to evaluate the antibacterial effect of sophorolipid in combination with lactic acid against relevant bacteria isolated from the poultry industry. Staphylococcus aureus, Listeria monocytogenes, Salmonella enterica, and Escherichia coli were isolated from chicken meat and antibacterial tests with sophorolipid and lactic acid were performed. Checkerboard, time-kill, and scanning electron microscopy analyses were used to confirm the antibacterial action and the combined effects. Although no inhibitory effects were observed for E. coli and Salmonella, these compounds presented antibacterial activity against L. monocytogenes and S. aureus. Additionally, sophorolipid and lactic acid were not cytotoxic at the concentrations used in the tests. The combination of sophorolipid and lactic acid resulted in an additive interaction, reducing the concentration of the active compounds needed for effectiveness against S. aureus and L. monocytogenes, to 50% and 75%, respectively. These findings lead to the possibility of developing a new, sustainable, and natural antimicrobial solution that is considered noncytotoxic and has wide applicability in the poultry industry to reduce substantial losses in this sector.

Utilization of agroindustrial byproducts for the production of lipase by a new strain of Pseudomonas sp / Utilização de subprodutos agroindustriais para a produção de lipase por uma nova cepa de Pseudomonas sp

This study aimed to evaluate the production of lipases by a new strain of Pseudomonas sp. using fermentation medium containing byproducts of poultry meat or soybean oil industry. The results indicate that chicken fat and soybean gum induced 48.3 U/mL and 93.3 of lipase activity, respectively. However, the higher lipase production was obtained when the crude lecithin gum was used, archiving 272.6 U/ml of activity after 24 hours. The partial biochemical characterization of the enzyme showed that the optimum reaction conditions were pH 9.0 and 35 °C. The enzyme was stable at temperatures between 25 to 75 °C and at pH from 6 to 9. The enzyme also showed good stability in organic solvents, such as acetronitrile, hexane, ethanol and isopropanol. This study indicates that the byproducts tested are promising for the production of lipase and can contribute to the reduction of enzymatic production costs on a large scale, increase the value of these byproducts and reduce potential environmental impacts caused by its accumulation in nature.(AU)

Este estudo teve como objetivo avaliar a produção de lipases por uma nova cepa de Pseudomonas sp. utilizando meio de fermentação contendo subprodutos de industrialização de carne de frango e óleo de soja. Os resultados indicaram que a gordura de frango e a goma de soja induziram 48,3 U/mL e 93,3 U/ml de atividade lipásica, respectivamente. No entanto, a produção de lipase mais elevada foi obtida quando a goma de lecitina bruta foi utilizada, induzindo 272,6 U/ml de atividade após 24 horas. A caracterização bioquímica parcial da enzima mostrou que as condições de reação ótimas foram de pH 9,0 e 35 °C. A enzima foi estável nas temperaturas entre 25 a 75 °C e pH de 6 a 9. A enzima mostrou boa estabilidade em solventes orgânicos, tais como acetonitrila, hexano, etanol e isopropanol. Este estudo indicou que os subprodutos testados são promissores para a produção de lipase e podem contribuir para a redução dos custos de produção enzimática em larga escala, aumentar o valor desses subprodutos e reduzir potenciais impactos ambientais causados por sua acumulação na natureza.(AU)

Films Based on Blends of Polyvinyl Alcohol and Microbial Hyaluronic Acid

Abstract The aims of this work were to produce hyaluronic acid (HA) by Streptococcus zooepidemicus ATCC 39920 in a low cost sugarcane molasses fermentation medium and to employ the produced HA to obtain films blends based on polyvinyl alcohol (PVA). The films were produced using solution casting method and they were characterized according to their microstructure, mechanical and barrier properties. HA was added in different concentrations (0, 5, 10 and 15% (w/w)), and glycerol was used as a plasticizer (25 g/100 g solids). All formulations resulted in easily manipulated films with good appearance. The addition of HA on PVA films increased their thermal stability, solubility, swelling index, water vapor permeability and elongation. Microbial HA sample combined with PVA showed to be a promising material to biomedical application, and an addition between 5 and 10% (w/w) was sufficient to improve PVA films properties.

Antibacterial Activity of Sophorolipids from Candida bombicola Against Human Pathogens

Abstract Sophorolipids are glycolipids that have natural antimicrobial properties and present great potential in the pharmaceutical field. The present study aimed to produce sophorolipids from Candida bombicola using a chicken fat-based medium and evaluate the antimicrobial activity against Gram-negative (Proteus mirabilis, Escherichia coli, Salmonella enterica subsp. enterica) and Gram-positive bacteria (Enterococcus faecium, Staphylococcus aureus and Streptococcus mutans). The production of sophorolipids reached 27.86 g L-1. Based on the structural characterization, 73.55% of the sophorolipids present a mixture of acidic monoacetylated C18:2 and lactonic diacetylated C16:0, and 26.45% were present in the diacetylated C18:1 lactonic form. Bacteria submitted to sophorolipid exposure showed a reduction in viability at doses of 500 μg mL-1 and 2,000 μg mL-1 against Gram-positive and Gram-negative bacteria, respectively. These results suggest that sophorolipids produced in chicken fat medium may be used as antimicrobial agents to prevent or eliminate contamination by different pathogens.

Co-production of Fructooligosaccharides and Levan by Levansucrase from Bacillus subtilis natto with Potential Application in the Food Industry.

Fructooligosaccharides and levan have a wide range of applications in the food industry due to their physiological and functional properties. The enzymatic synthesis of these molecules exhibits great advantages when compared with microbial fermentation. In this study, the production of levansucrase from Bacillus subtilis natto and its utilization in fructooligosaccharides and levan syntheses using different reaction conditions were described. The best condition for levansucrase production was 420.7 g L-1 of sucrose at pH 7.0, which reached 23.9 U ml-1 of transfructosylation activity. In a bioreactor, the highest production of fructooligosaccharides was 41.3 g L-1 using a medium containing 350 g L-1 sucrose at 35 °C for 36 h. The enzymatic synthesis of levan resulted in 86.9 g L-1 when conditions similar to those used for fructooligosaccharides synthesis were applied. These results indicate that the levansucrase from B. subtilis natto could be applied for the co-production of fructooligosaccharides and levan, which are biomolecules that have health benefits and are used successfully in the food industry.

Improvement Production of Hyaluronic Acid by Streptococcus zooepidemicus in Sugarcane Molasses.

Microbial hyaluronic acid (HA) production has been preferred rather than extraction from animal tissue for medical and cosmetic applications. In this context, to obtain an economically competitive HA production by Streptococcus zooepidemicus, culture conditions were studied to improve the polymer production in sugarcane molasses. The highest HA production by S. zooepidemicus ATCC 39920 achieved was 2.825 g. L-1 in a 4.5 L bioreactor with controlled pH (8.0) and medium containing molasses (85.35 g.L-1 total sugar) pretreated with activated charcoal and yeast extract (50 g.L-1). The HA produced exhibited a high molecular weight of 1.35 × 103 kDa and the DPPH radical scavenging activity of the polymer at 1 g.L-1 was 41 %. The FTIR and UV-Vis spectra showed no substantial differences in the spectral pattern between produced and standard HA. This study is a promising strategy for sugarcane molasses application by producing high value-added products such as hyaluronic acid.

Edible films based on cassava starch and fructooligosaccharides produced by Bacillus subtilis natto CCT 7712.

The objectives of this work were to produce fructooligosaccharides (FOSs) by using the microorganism Bacillus subtilis natto CCT 7712 and to employ these FOSs as a functional ingredient in cassava starch edible films, which were characterized according to their microstructure, mechanical and barrier properties. The produced FOSs could be easily dissolved, resulting in homogeneous filmogenic solutions, which were easily manipulated to obtain films by casting. FOSs were added in different concentrations (0, 1, 5 and 10g/100g solids), and glycerol was used as a plasticizer (20g/100g solids). All formulations resulted in films that had a good appearance and were easily removable from the plates without bubbles or cracks. The FOSs exerted a plasticizing effect on the starch films and decreased their glass transition temperature. The addition of FOSs resulted in higher solubility and elongation and a decreased water vapor permeability of the films. FOSs were shown to be a promising ingredient for use in edible starch films.

Optimization of asparaginase production from Zymomonas mobilis by continuous fermentation / Otimização da produção de asparaginase de Zymomonas mobilis por fermentação contínua

A asparaginase é uma enzima usada em tratamento clínico como agente quimioterapêutico e em tecnologia de alimentos na prevenção de formação de acrilamida em alimentos fritos e assados. Asparaginase é industrialmente produzida por micro-organismos, principalmente bactérias gram negativas. Zymomonas mobilis é uma bactéria gram negativa que utiliza glicose, frutose e sacarose como fonte de carbono e é conhecida por sua eficiência para produzir etanol, sorbitol, levana, ácido glicônico, e mais recentemente, tem despertado interesse no uso desse micro-organismo na produção de asparaginase. Este trabalho teve como objetivo otimizar a produção de asparaginase de Z. mobilis por fermentação contínua, pelo uso do delineamento experimental e da metodologia da superfície de resposta, testando as variáveis: sacarose, extrato de levedura e asparagina. A condição ótima alcançada, com produção de 117,45 UI L-1 foi na taxa de diluição 0,20 h-1, utilizando 0,5 g L-1 de extrato de levedura, 20 g L-1 de sacarose e 1,3 g L-1 de asparagina. Observou-se que a relação carbono:nitrogênio (1:0,025) exerceu forte influência na resposta da atividade de asparaginase. A utilização de Z. mobilis por fermentação contínua demonstrou ser uma alternativa promissora na produção biotecnológica da asparaginase.

Asparaginase is an enzyme used in clinical treatments as a chemotherapeutic agent and in food technology to prevent acrylamide formation in fried and baked foods. Asparaginase is industrially produced by microorganisms, mainly gram-negative bacteria. Zymomonas mobilis is a Gram-negative bacterium that utilizes glucose, fructose and sucrose as carbon source and has been known for its efficiency in producing ethanol, sorbitol, levan, gluconic acid and has recently aroused interest for asparaginase production. Current assay optimizes the production of Z. mobilis asparaginase by continuous fermentation using response surface experimental design and methodology. The studied variables comprised sucrose, yeast extract and asparagine. Optimized condition obtained 117.45 IU L-1 with dilution rate 0.20 h-1, yeast extract 0.5 g L-1, sucrose 20 g L-1 and asparagine 1.3 g L-1. Moreover, carbon:nitrogen ratio (1:0.025) strongly affected the response of asparaginase activity. The use of Z. mobilis by continuous fermentation has proved to be a promising alternative for the biotechnological production of asparaginase.

Effect of fermentation conditions on the production of hyaluronic acid by Streptococcus zooepidemicus ATCC 39920 / Efeito das condições de fermentação na produção de ácido hialurônico por Streptococcus zooepidemicus ATCC 39920

The production of hyaluronic acid by Streptococcus zooepidemicus ATCC 39920 with varying rates of pH (6.0, 7.0, 8.0), temperature (34; 37; 40°C), agitation (100, 150, 200 rpm), glucose (10, 20, 30 g L -1) and yeast extract concentration (10, 20, 30 g L -1) was evaluated by statistical approaches. The best conditions for the production of hyaluronic acid was pH 8.0, 37°C and 100 rpm in a medium containing 30 g L- 1 glucose and yeast extract, for a production of 0.787 g L- 1. Temperature, pH and yeast extract were significant variables (p < 0.05). Yeast extract and pH had a positive effect on the production of the polymer. Lactate, formate and acetate synthesis were also analyzed. Current assay showed the feasibility of statistical tools to optimize the physical and nutritional parameters for the production of hyaluronic acid and the improvement of the fermentation process.

A produção de ácido hialurônico por Streptococcus zooepidemicus ATCC 39920 foi avaliada variando pH (6,0; 7,0, 8,0), temperatura (34; 37; 40°C), agitação (100, 150, 200 rpm) e concentração de glicose (10, 20, 30 g L-1) e extrato de levedura (10, 20, 30 g L-1) por metodologias estatísticas. A condição otimizada foi pH 8,0, 37°C e 100 rpm, em meio contendo 30 g L-1 de glicose e extrato de levedura atingindo a produção de 0,787 g L-1. O pH, temperatura e extrato de levedura foram as variáveis significativas (p < 0,05). Extrato de levedura e pH apresentaram efeito positivo para a produção do polímero. A síntese de ácido lático, fórmico e acético também foi analisada. Este estudo demonstra a viabilidade de utilização de ferramentas estatísticas para otimizar os parâmetros físicos e nutricionais para a produção de ácido hialurônico, permitindo a melhoria do processo fermentativo.

Levan from Bacillus subtilis Natto: its effects in normal and in streptozotocin-diabetic rats

Levan is an exopolysaccharide of fructose primarily linked by ƒÀ-(2¨6) glycosidic bonds with some ƒÀ-(2¨1) branched chains. Due to its chemical properties, levan has possible applications in both the food and pharmaceutical industries. Bacillus subtilis is a promising industrial levan producer, as it ferments sucrose and has a high levan-formation capacity. A new strain of B. subtilis was recently isolated from Japanese food natto, and it has produced levan in large quantities. For future pharmaceutical applications, this study aimed to investigate the effects of levan produced by B. subtilis Natto, mainly as potential hypoglycemic agent, (previously optimized with a molecular weight equal to 72.37 and 4,146 kDa) in Wistar male rats with diabetes induced by streptozotocin and non-diabetic rats and to monitor their plasma cholesterol and triacylglycerol levels. After 15 days of experimentation, the animals were sacrificed, and their blood samples were analyzed. The results, compared using analysis of variance, demonstrated that for this type of levan, a hypoglycemic effect was not observed, as there was no improvement of diabetes symptoms during the experiment. However, levan did not affect any studied parameters in normal rats, indicating that the exopolysaccharide can be used for other purposes.

Levan in the developing of new colon-specific polymer material: evaluation of the permeability, moisture and thermal analyses in free films of Eudragit® FS 30 D / Levana no desenvolvimento de novo material polimérico cólon-específico: avaliação da permeabilidade, intumescimento e análises térmicas de filmes isolados de Eudragit® FS 30 D

Levan was used as agent in the synthesis of new colon-specific polymeric matrix together with Eudragit® FS 30 D. Eudragit® FS 30 D films incorporated with levan were made by casting process and characterized to: water vapour transmission, sweeling index, differential scanning calorimetry and thermogravimetric. The levan increased the films permeability (p < 0.001) however did not influenced in the sweeling index of the formulations (p > 0.05). The thermal analyses of the films indicated a glass transition temperature approximate at 47°C and thermal decomposition at 400°C. The results indicated that there is potential for using such site-specificity blend as pharmaceutical coating material.

Levana foi utilizada na síntese de novo material polimérico cólon-específico conjuntamente com o Eudragit® FS 30 D. Filmes de Eudragit® FS 30 D aditivados de levana foram feitos pelo método de "casting process" e caracterizados quanto à transmissão de vapor de água, índice de intumescimento, calorimetria diferencial de varredura e termogravimetria. A levana aumentou a permeabilidade dos filmes (p < 0,001), entretanto não influenciou no índice de intumescimento das formulações (p > 0,05). As análises térmicas dos filmes indicaram uma temperatura de transição vítrea aproximada de 47°C e temperatura de decomposição de 400°C. Os resultados indicaram que há potencial de uso desta nova blenda sítio-específica como material de revestimento farmacêutico.

Levan from Bacillus subtilis Natto: its effects in normal and in streptozotocin-diabetic rats.

Levan is an exopolysaccharide of fructose primarily linked by ß-(2→6) glycosidic bonds with some ß-(2→1) branched chains. Due to its chemical properties, levan has possible applications in both the food and pharmaceutical industries. Bacillus subtilis is a promising industrial levan producer, as it ferments sucrose and has a high levan-formation capacity. A new strain of B. subtilis was recently isolated from Japanese food natto, and it has produced levan in large quantities. For future pharmaceutical applications, this study aimed to investigate the effects of levan produced by B. subtilis Natto, mainly as potential hypoglycemic agent, (previously optimized with a molecular weight equal to 72.37 and 4,146 kDa) in Wistar male rats with diabetes induced by streptozotocin and non-diabetic rats and to monitor their plasma cholesterol and triacylglycerol levels. After 15 days of experimentation, the animals were sacrificed, and their blood samples were analyzed. The results, compared using analysis of variance, demonstrated that for this type of levan, a hypoglycemic effect was not observed, as there was no improvement of diabetes symptoms during the experiment. However, levan did not affect any studied parameters in normal rats, indicating that the exopolysaccharide can be used for other purposes.

Influence of high osmotic pressure on sorbitol production by Zymomonas mobilis

The objective of the present work was to study the variation on the sorbitol production in relation to the concentration of sugars, (metabolizable or not) and the cultivation time. A full factorial design was used considering the factors such as sucrose and maltose concentration and cultivation time. The addition of sugars caused increases on the sorbitol production up to the concentration of 300g/L however, decreases on the sorbitol production were observed when the concentration reached values above this. Increasing the time of fermentation was statistically significant to sorbitol production, however, little increase the production was noticed after 36h.

Zymomonas mobilis produz o poliálcool sorbitol como principal subproduto. Sua formação é atribuída principalmente a sua função A produção de sorbitol foi avaliada através de um planejamento fatorial completo utilizando as variáveis concentração de sacarose, concentração de maltose e tempo de cultivo. A adição de açúcares causou um aumento na produção de sorbitol até a concentração de 300g/L, porém decréscimos na produção de sorbitol foram observados a concentrações superiores a esta. Aumento no tempo de fermentação foi estatisticamente significativo para aumentos da produção de sorbitol, porém pequeno aumento foi observado de 12 para 36 horas de cultivo.

Evaluation of supplementation of sucrose medium on the synthesis of Zymomonas mobilis bio-products / Avaliação da suplementação do meio de sacarose na formação de bio–produtos por Zymomonas mobilis

The effect of the variables pantothenic acid, yeast extract and sodium chloride, as well as the cell permeabilization technique, were investigated on the formation of levan, ethanol, sorbitol and biomass of Zymomonas mobilis, using a 24-1 fraction factorial design. Cell growth was determined by turbidimetry at 605 nm, relating it to a biomass with a dry weight calibration curve. Reducing sugars were quantified according to Somogyi and Nelson. Total sugars were quantified by the phenol-sulfuric acid method, sorbitol by HPLC and ethanol. The levan produced was precipitated by the addition of absolute ethanol and quantified in fructose units. In levan biosynthesis, the variable that had the largest contribution was cell condition. The results suggested that the factors that most affected biomass and ethanol formation were sodium chloride concentration and cell condition that affected negatively on production. For sorbitol, the variable that had a significant effect was permeabilization, which decreased its synthesis. Studies to amplify the range of established factors would be important.

A influência das variáveis: ácido pantotênico, extrato de levedura, cloreto de sódio, e a técnica de permeabilização celular foram investigadas na formação de levana, sorbitol, etanol e biomassa de Zymomonas mobilis utilizando um delineamento estatístico fatorial fracionado 24-1. A biomassa foi determinada por turbidimetria, Os açúcares redutores foram quantificados por Somogy e Nelson, açúcar total por Fenol Sulfúrico, sorbitol por HPLC e etanol por micro-destilação. A levana produzida foi precipitada com etanol absoluto e determinada como unidade de frutose. Na biossíntese de levana, a variável que mais contribuiu foi a condição celular. Os resultados sugerem que, para a formação da biomassa e etanol, os fatores que mais interferiram foram a concentração de cloreto de sódio e a condição celular que influencia negativamente a produção. Para o sorbitol, a variável que teve efeito significativo foi a permeabilização celular que atuou diminuindo a sua síntese. Estudos que ampliam a faixa de variação dos fatores estabelecidos são interessantes.

Uso de matérias primas da agroindústria: garapa e extrato de levedura: na produção de asparaginase por Zymomonas mobilis CP4 / Utilization of raw materials from agroindustry: sugar cane juice and yeast extract: for asparaginase production by Zymomonas mobilis CP4

Garapa e extrato de levedura foram usados na produção de asparaginase por Zymomonas mobilis CP4. Na otimização utilizou metodologia de superfície de resposta com 2 variáveis (extrato de levedura e asparagina) em 3 níveis (1,0; 5,5 e 10,0 g/L) e uma repetição do ponto central. A fermentação em batelada utilizou garapa diluída a 8 % (P/V) de Açúcares Totais e inóculo de Zymomonas mobilis CP4 na concentração de 2 mg/mL. Após a fermentação de 18 horas, a maior produção obtida de asparaginase foi de 9,75 U/L em extrato de levedura em 5,5 g/L e asparagina em 1,0 g/L.

Sugar cane juice and yeast extract have been used for asparaginase production by Z. mobilis CP4. A complete factorial design of two variables (yeast extract and asparagin) at three levels (1.0; 5.5 and 10.0 g/L) with one replication at the central point was used. Batch fermentation utilised sugar cane juice diluted at 8 % (W/V) of Total Sugars and an inoculum of 2 mg of cells/mL. After fermentation time of 18 hours, the highest production of asparaginase was 9.75 U/L using both yeast extract (5.5 g/L) and asparagin (1.0 g/l).

Effect of raffinose and ultrasound pulses on invertase release by free and immobilized Saccharomyces cerevisiae in loofa (Luffa cylindrica) sponge

This study investigated the effect of raffinose and ultrasound pulses on invertase release from free S. cerevisiae and S. cerevisiae immobilized in Luffa cylindrica. The free cell culture was submitted to 2 percent raffinose pulse and irradiated for 2 minutes at 0.12 and 0.46 h-1 dilution rates. The immobilized cell culture was submitted to raffinose pulse and irradiated for 1, 2 and 4 minutes, at 0.10 h-1 dilution rate. In immobilized cells, the raffinose pulse increased the invertase activity from 5.38 to 7.27 U/mg. Ultrasound application in free cell culture at the 0.12 h-1 dilution rate gave the best results. The activity varied from 25.08 to 29.38 U/mg while the increase in immobilized cells was from 5.22 to 9.70 U/mg when sonicated for two minutes. These results showed that ultrasound application in continuous culture could have great potential for application in biotechnological techniques.

Neste trabalho investigou-se o efeito de pulsos de rafinose e ultra-som, na liberação de invertase de Saccharomyces cerevisiae livre e imobilizado em Luffa cylindrica. A cultura de células livres foi submetida a pulso de rafinose 2 por cento e irradiada por 2 min, nas taxas de diluição 0,12 e 0,46 h-1. A cultura de células imobilizadas foi submetida a pulso de rafinose e irradiada por 1, 2 e 4 min, em taxa de diluição 0,10 h-1. Em células imobilizadas, o pulso de rafinose aumentou a atividade invertásica de 5,38 para 7,27 U/mg. Entretanto a aplicação do ultra-som, em cultivo de células livres na taxa de diluição 0,12 h-1, obteve-se os melhores resultados. A atividade variou de 25,08 para 29,38 U/mg, enquanto que o aumento em células imobilizadas foi de 5,22 para 9,70 U/mg, quando sonicadas por 2 min. Esses resultados demonstram que a aplicação de ultra-som, em cultivo contínuo de células livres, pode ter um grande potencial de aplicação em processos biotecnológicos.

Synthesis of sorbitol by Zymomonas mobilis under high osmotic pressure

The bacterium Zymomonas mobilis presents potential for sorbitol production when grown in culture medium with high sugar concentration. Sorbitol is produced and accumulated in the periplasma of the bacterium to protect the cells from the harmful effects of high osmotic pressure that results from the action of invertase on sucrose. The conversion of sucrose into glucose and fructose increases the osmolarity of the medium. However, an excessive increase in the osmotic pressure may decrease the sorbitol production. In this work Saccharomyces cerevisiae invertase was added two media containing sucrose 200 and 300 g.L-1. Sorbitol production in sucrose at 200 g.L-1 was 42.35 and 38.42 g.L-1, with and without the invertase treatment, respectively. In the culture medium with 300 g.L-1 sucrose, production reached 60.4 g.L-1 and with invertase treatment was 19.14 g.L-1. These results indicated that the excessive rise in osmotic pressure led to a significant decrease in sorbitol production by the Zymomonas mobilis bacterium in the sucrose medium treated with invertase.

A bactéria Zymomonas mobilis, apresenta potencial para produção de sorbitol quando crescida em meio com alta concentração de açúcar. O sorbitol produzido é acumulado no periplasma da bactéria para conter os efeitos prejudiciais da elevada pressão osmótica, que resulta pela ação da enzima invertase, que promove hidrólise da sacarose. A conversão da sacarose em glicose e frutose aumentando a osmolaridade do meio. Entretanto, um aumento excessivo na pressão osmótica pode inibir a produção de sorbitol pela bactéria. Este trabalho empregou invertase de Saccharomyces cerevisiae nos meios de fermentação com sacarose a 200 e 300 g.L-1. A produção de sorbitol no meio com sacarose a 200 g.L-1 foi de 42,35 g.L-1 e 38,42 g.L-1 com e sem tratamento com invertase respectivamente. No meio com 300 g.L-1 sem tratamento, a produção foi de 60,42 e com tratamento 19,14 g.L-1. Estes resultados indicaram que a elevação excessiva da pressão osmótica, pela adição de invertase levou a uma diminuição significativa na produção de sorbitol pela bactéria Zymomonas mobilis.