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.

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.