Use of brewer's residual yeast for production of bacterial nanocellulose with Gluconacetobacter hansenii.

Bacterial nanocellulose (BNC) has attained elevated interest due to its versatile structure and high resistance characteristics. Accordingly, efforts have been made in order to reduce its production costs, such as the employment of its by-products as a nutrient broth to yield the microorganism. Residual brewer's yeast is an excellent recourse, due to its high nutritional value and availability. Therefore, research which aimed to contribute to the development of a low cost, efficient and biosustainable technology for BNC production with Gluconacetobacter hansenii was carried out. BNC was obtained from residual brewer's yeast hydrolysate at pH 7.0 and five days of incubation at 30 °C in static culture. The hydrolysate was characterized by the amount of sugars, fatty acids, total proteins and ash content. Subsequently, BNC obtained was characterized in terms of yield, carbon conversion ratio, hydrodynamic size, crystallinity, morphology, Fourier-transform infrared spectroscopy, and surface analysis. Residual brewer's yeast hydrolysate proved to be efficient in BNC production via gluconeogenesis with consumption of alanine, threonine and glycerol, obtaining 1.9 times the yield of the chemically defined broth adopted as standard. Additionally, properties observed in the obtained BNC were equal to those obtained from conventional chemical medium. The research contributed to bacterial nanocellulose production using by-products from the brewing industry.

Cytotoxicity, structural, conformational, and techno-functional properties of α-lactalbumin nanostructured aggregates.

Protein nanostructures can be used in food applications to improve the techno-functional properties of a food formulation. This study aims to find the best conditions for the production and conformational change of α-lactalbumin nanostructured aggregates. The criteria to determine the best operating conditions to produce α-lactalbumin nanostructured aggregates were intensification of foaming and emulsification, techno-functional proprieties, cytotoxic, and antibacterial activity of nanostructures compared with native α-lactalbumin. Conformational alterations occurred in the α-helix and sheet-ß protein structures. The size obtained by dynamic light scattering was 163.84 nm with a polydispersity index of 0.29. The nano protein improved the techno-functional property compared to the native protein. Additionally, nanostructures had no cytotoxic effect and were innocuous to bacterial activity. Thus, this study presents the best conditions to produce α-lactalbumin nanostructured aggregates with improved properties that allow new food industry applications.

Monitoring bioreactors using principal component analysis: production of penicillin G acylase as a case study.

The complexity of biological processes often makes impractical the development of detailed, structured phenomenological models of the cultivation of microorganisms in bioreactors. In this context, data pre-treatment techniques are useful for bioprocess control and fault detection. Among them, principal component analysis (PCA) plays an important role. This work presents a case study of the application of this technique during real experiments, where the enzyme penicillin G acylase (PGA) was produced by Bacillus megaterium ATCC 14945. PGA hydrolyzes penicillin G to yield 6-aminopenicilanic acid (6-APA) and phenyl acetic acid. 6-APA is used to produce semi-synthetic beta-lactam antibiotics. A static PCA algorithm was implemented for on-line detection of deviations from the desired process behavior. The experiments were carried out in a 2-L bioreactor. Hotteling's T(2) was the discrimination criterion employed in this multivariable problem and the method showed a high sensibility for fault detection in all real cases that were studied.

Assessment of the metabolism of different strains of Bacillus megaterium

Bacillus megaterium is a promising host for expression of heterologous proteins. This paper reports the nutrient consumption patterns and production of metabolites for three different strains of B. megaterium, ATCC 14945, QMB 1551 and PV 361, which is QMB 1551 with seven constitutive plasmids deleted. 14 h cultivations in agitated flasks were run, for two different media: A (LB plus 10g/L glucose) and B (medium A, with the yeast extract replaced by tryptone). Strains PV361 and QMB 1551 showed higher maximum specific growth rates in medium B, reaching 0.42 h-1 and 0.48 h-1 respectively. The main by-products of the glucose overflow mechanism were acetate and lactate, for all three strains, which had preferential amino acids for substrate: Ala, Asp, Glu, Ser. No production of alcohols was detected.