RESUMEN
Klebsiella pneumoniae (Kp) is a Gram-negative bacterium, and a leading cause of neonatal sepsis in low- and middle-income countries, often associated with anti-microbial resistance. Two types of polysaccharides are expressed on the Kp cell surface and have been proposed as key antigens for vaccine design: capsular polysaccharides (known as K-antigens, K-Ags) and O-antigens (O-Ags). Historically, Kp has been classified using capsule serotyping and although 186 distinct genotypes have been predicted so far based on sequence analysis, many structures are still unknown. In contrast, only 11 distinct OAg serotypes have been described. The characterization of emerging strains requires the development of a high-throughput purification method to obtain sufficient K- and O-Ag material to characterize the large collection of serotypes and gain insight on structural features and potential cross-reactivity that could allow vaccine simplification. Here, this was achieved by adapting our established method for the simple purification of O-Ags, using mild acetic acid hydrolysis performed directly on bacterial cells, followed by filtration and precipitation steps. The method was successfully applied to purify the surface carbohydrates from different Kp strains, thereby demonstrating the robustness and general applicability of the purification method developed. Further, antigen characterization showed that the purification method had no impact on the structural integrity of the polysaccharides and preserved labile substituents such as O-acetyl and pyruvyl groups. This method can be further optimized for scaling up and manufacturing to support the development of high-valency saccharide-based vaccines against Kp.
RESUMEN
Meat represents an important protein source, even in developing countries, but its production is scarcely sustainable, and its excessive consumption poses health issues. An increasing number of Western consumers would replace, at least partially, meat with alternative protein sources. This review aims at: (i) depicting nutritional, functional, sensory traits, and critical issues of single-cell proteins (SCP), filamentous fungi, microalgae, vegetables (alone or mixed with milk), and insects and (ii) displaying how fermentation could improve their quality, to facilitate their use as food items/ingredients/supplements. Production of SCP (yeasts, filamentous fungi, microalgae) does not need arable land and potable water and can run continuously, also using wastes and byproducts. Some filamentous fungi are also consumed as edible mushrooms, and others are involved in the fermentation of traditional vegetable-based foods. Cereals, pseudocereals, and legumes may be combined to offer an almost complete amino acid profile. Fermentation of such vegetables, even in combination with milk-based products (e.g., tarhana), could increase nutrient concentrations, including essential amino acids, and improve sensory traits. Different insects could be used, as such or, to increase their acceptability, as ingredient of foods (e.g., pasta). However, insects as a protein source face with safety concerns, cultural constraints, and a lack of international regulatory framework.
RESUMEN
Increasing preference of consumers and bakers towards bread manufactured with mixed flours and/or sourdough drove us to investigate about influence of flours and sourdough on crumb grain, chemical, sensory, and in vitro glycaemic index (GI) and antioxidant activity of bread. To this aim, we produced and compared six experimental breads: three were based on a mixture of flours (soft wheat, durum wheat semolina, barley, oat, rye, and buckwheat); three were semolina-based breads. Two different sourdoughs (wheat or mixed flours) were assessed. Compared to semolina breads, those containing a mixture of flours showed higher specific volume. The use of sourdough led to increased concentrations of total free amino acids (FAA). Mixed flours bread with addition of mixed flours sourdough was rich in some essential FAA and amino acid derivative bioactive gamma-aminobutyric acid. Type of flours had higher influence than sourdough addition on volatile organic compounds. All the mixed flours breads, although showing profiles of volatile organic compounds differing from those of semolina breads, resulted acceptable. In addition, they had lower GI and higher antioxidant activity than semolina breads. Type of flours had much higher impact on GI and antioxidant activity than sourdough.
