Different Flour Microbial Communities Drive to Sourdoughs Characterized by Diverse Bacterial Strains and Free Amino Acid Profiles

This work aimed to investigate whether different microbial assemblies in flour may influence the microbiological and biochemical characteristics of traditional sourdough. To reach this purpose, members of lactic acid bacteria, enterobacteria, and yeasts were isolated from durum wheat flour. Secondly, the isolated microorganisms (Pediococcus pentosaceus, Saccharomyces cerevisiae, Pantoea agglomerans, and Escherichia hermannii) were inoculated in doughs prepared with irradiated flour (gamma rays at 10 kGy), so that eight different microbial assemblies were obtained. Two non-inoculated controls were prepared, one of which (C-IF) using irradiated flour and the other (C) using non-irradiated flour. As shown by plate counts, irradiation of flour caused total inactivation of yeasts and a decrease of all the other microbial populations. However, acidification occurred also in the dough C-IF, due to metabolic activity of P. pentosaceus that had survived irradiation. After six fermentations, P. pentosaceus was the dominant lactic acid bacterium species in all the sourdoughs produced with irradiated flour (IF). Yet, IF-based sourdoughs broadly differed from each other in terms of strains of P. pentosaceus, probably due to the different microorganisms initially inoculated. Quantitative and qualitative differences of free amino acids concentration were found among the sourdoughs, possibly because of different microbial communities. In addition, as shown by culture-independent analysis (16S metagenetics), irradiation of flour lowered and modified microbial diversity of sourdough ecosystem

Genetic and ecological inheritance of plant growth-promoting rhizobacteria

Background: The utilization of beneficial (Rhizo) bacteria, as an alternative to traditional fertilizers, has emerged as an eco-friendly strategy for ameliorating sustainable agricultural production. This approach aims to reduce the use of agrochemicals and minimize environmental pollution.ScopeThis review provides an updated insight into the ecological impact of plant growth-promoting rhizobacteria (PGPR), focusing on the resident microbiome and its potential transferability to the next generation of plants.ConclusionIn this context, PGPR are assumed to alter the rhizosphere microbiome by outcompeting the existing taxa through nutrient deprivation, acidification of the environment, metabolites production, and consequently, increasing the copiotrophic taxa. Such modifications can maximize the beneficial interactions of plant-PGPR by increasing the bioavailability of nutrients and handling diverse signaling pathways. The effects of interactions within the PGPR-root system can adjust the composition of root exudates and influence the release of bioactive molecules by the root, especially under stress conditions, which can act as signals to reactivate and recruit the beneficial microbes in the rhizosphere and endosphere in favor of the plants. Such changes in microbiome structure can occur gradually over time, even if the survival rate of PGPR in soil and their re-colonization efficiency inside plant tissue are limited. The aforementioned modifications in the rhizosphere and plant microbiome have the potential to increase the survival chances of the progeny plants growing under the same stress conditions. Establishing a comprehensive and robust knowledge framework that addresses all of these issues is critical for significantly advancing the field of microbe-plant interactions and for developing reliable applications of PGPR

Microbial Ecology Dynamics during Rye and Wheat Sourdough Preparation

ABSTRACT The bacterial ecology during rye and wheat sourdough preparation was described by 16S rRNA gene pyrosequencing. Viable plate counts of presumptive lactic acid bacteria, the ratio between lactic acid bacteria and yeasts, the rate of acidification, a permutation analysis based on biochemical and microbial features, the number of operational taxonomic units (OTUs), and diversity indices all together demonstrated the maturity of the sourdoughs during 5 to 7 days of propagation. Flours were mainly contaminated by metabolically active genera ( Acinetobacter , Pantoea , Pseudomonas , Comamonas , Enterobacter , Erwinia , and Sphingomonas ) belonging to the phylum Proteobacteria or Bacteroidetes (genus Chryseobacterium ). Their relative abundances varied with the flour. Soon after 1 day of propagation, this population was almost completely inhibited except for the Enterobacteriaceae . Although members of the phylum Firmicutes were present at very low or intermediate relative abundances in the flours, they became dominant soon after 1 day of propagation. Lactic acid bacteria were almost exclusively representative of the Firmicutes by this time. Weissella spp. were already dominant in rye flour and stably persisted, though they were later flanked by the Lactobacillus sakei group. There was a succession of species during 10 days of propagation of wheat sourdoughs. The fluctuation between dominating and subdominating populations of L. sakei group, Leuconostoc spp., Weissella spp., and Lactococcus lactis was demonstrated. Other subdominant species such as Lactobacillus plantarum were detectable throughout propagation. As shown by PCR-denaturing gradient gel electrophoresis (PCR-DGGE) analysis, Saccharomyces cerevisiae dominated throughout the sourdough propagation. Notwithstanding variations due to environmental and technology determinants, the results of this study represent a clear example of how the microbial ecology evolves during sourdough preparation. </jats:p

Protein sources alternative to meat: state of the art and involvement of fermentation

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.info:eu-repo/semantics/publishedVersio

Massive non-natural proteins structure prediction using grid technologies

Background The number of natural proteins represents a small fraction of all the possible protein sequences and there is an enormous number of pr oteins never sampled by nature, the so called "never born proteins" (NBPs). A fundamental question in this regard is if the ensemble of natural proteins possesses peculiar chemical and physical properties or if it is just the product of contingency coupled to functional selection. A key feature of natural proteins is thei r ability to form a well defined three-dimensional structure. T hus, the structural study of NBPs can help to understand if natural protein sequences were selecte d for their peculiar properties or if they are just one of the possible stable and functional ensembles. Methods The structural characterization of a huge number of random proteins cannot be approached experimentally, thus the problem has been tackled using a computational approach. A large random protein sequences library (2 × 10 ^4 sequences) was generated, discarding amino acid sequences with significant simi larity to natural proteins, and the corresponding structures were predicted using Rosetta. Given th e highly computational demanding problem, Rosetta was ported in grid and a user friendly job submission environment was developed within the GENIUS Grid Portal. Protein structures generated were analysed in terms of net charge, secondary structure content, surface/volume ratio, hydrophobic core composition, etc. Results The vast majority of NBPs, according to the Rosetta mode l, are characterized by a compact three-dimensional structure with a high secondary structure content. Structure compactness and surface polarity are comparable to those of natural proteins, suggesting similar stability and solubility. Deviations are observed in α helix- β strands relative content and inydrophobic core composition, as NBPs appear to be richer in helical structure and aromatic amino acids with respect to natural proteins. Conclusion The results obtained suggest that the abil ity to form a compact, ordered and water-soluble structure is an intrinsic property of polypeptides. The tendency of random sequences to adopt α helical folds indicate that all-α proteins may have emerged ea rly in pre-biotic evolution. Further, the lower percentage of aromatic residu es observed in natural proteins has important evolutionary implications as far as tolerance to mutati ons is concerned

Manufacture of a functional fermented milk enriched of Angiotensin-I Converting Enzyme (ACE)-inhibitory peptides and γ-amino butyric acid (GABA)

Abstract This study aimed at developing and characterizing a fermented milk with a potentially anti-hypertensive effect due to the concurrent presence of Angiotensin-I Converting Enzyme (ACE)-inhibitory peptides and γ-amino butyric acid (GABA). Preliminarily, lactic acid bacteria strains were screened based on the capacity of releasing ACE-inhibitory peptides and of synthesizing GABA. The most potent RP-FPLC fraction from the milk fermented with Lactococcus lactis DIBCA2 had an ACE-inhibitory activity, expressed in terms of IC 50 , of 5 ± 2 μg/mL, a value which compares well to those reported for the majority of ACE-inhibitory peptides identified in fermented milks. This fraction contained a mixture of six peptides, five of which shared motifs in common with ACE-inhibitory peptides previously reported. Lactobacillus plantarum PU11 was selected as the highest producer of GABA, ca. 77.4 mg/kg after 120 h of milk fermentation. Both the strains were selected and used as starters for consecutive milk fermentation. After fermentation, the milk contained both the lactic acid bacteria at the cell density of ca. 8.0 log CFU/mL, had a pH of ca. 4.45, and showed ACE-inhibitory activity (IC 50 = 0.70 ± 0.07 mg/mL) and a concentration of GABA (ca. 144.5 mg/kg), which were compatible with the dosage for mild antihypertensive effect

Nutritional, Biochemical, and Functional Properties of Spinach Leaf-Enriched Dough: A Healthier Alternative to Conventional Pasta

This study explored the effects of spinach flour (SF) enrichment on pasta, focusing on chemical, nutritional and sensory properties, cooking performance, and microbiological stability. SF was added at 12.5% (PSP12) and 25% (PSP25). The enriched pasta had a lower pH than the control (CP), due to spinach-derived organic acids, with PSP25 showing the highest fiber content. Enrichment increased B vitamins and minerals, especially calcium, magnesium, sodium, and potassium. PSP25 had a shorter cooking time, higher water absorption, and greater cooking loss. Enriched pasta showed lower starch hydrolysis index and predicted glycemic index, suggesting potential benefits for managing postprandial blood sugar levels. SF significantly altered the free amino acid (FAA) profile, with PSP25 showing the highest concentration of total FAAs. Antioxidant assays demonstrated that spinach-enriched pasta retained higher levels of phenols and flavonoids, after cooking also, compared to CP. Sensory analysis indicated that while PSP12 had higher overall acceptability, PSP25 exhibited stronger herbaceous flavors, which could affect consumer preference. Microbiologically, all samples were stable for 110 days. The findings suggest that SF enrichment enhances the nutritional value, antioxidant potential, and sensory qualities of pasta, with potential for commercial applications, although consumer acceptance could be influenced by its non-traditional taste and texture

Sustainable and Health-Protecting Food Ingredients from Bioprocessed Food by-Products and Wastes

Dietary inadequacy and nutrition-related non-communicable diseases (N-NCDs) represent two main issues for the whole society, urgently requesting solutions from researchers, policy-makers, and other stakeholders involved in the health and food system. Food by-products and wastes (FBPW) represent a global problem of increasing severity, widely recognized as an important unsustainability hotspot, with high socio-economic and environmental costs. Yet, recycling and up-cycling of FBPW to produce functional foods could represent a solution to dietary inadequacy and risk of N-NCDs onset. Bioprocessing of FBPW with selected microorganisms appears to be a relatively cheap strategy to yield molecules (or rather molecules mixtures) that may be used to fortify/enrich food, as well as to formulate dietary supplements. This review, conjugating human health and sustainability in relation to food, describes the state-of-the-art of the use of yeasts, molds, and lactic acid bacteria for producing value-added compounds from FBPW. Challenges related to FBPW bioprocessing prior to their use in food regard will be also discussed: (i) loss of product functionality upon scale-up of recovery process; (ii) finding logistic solutions to the intrinsic perishability of the majority of FBPW; (iii) inserting up-cycling of FBPW in an appropriate legislative framework; (iv) increasing consumer acceptability of food and dietary supplements derived from FBPWThis research was funded by the project SYSTEMIC “an integrated approach to the challenge of sustainable food systems: adaptive and mitigatory strategies to address climate change and malnutrition”, Knowledge hub on Nutrition and Food Security, that has received funding from national research funding parties in Belgium (FWO), France (INRA), Germany (BLE), Italy (MIPAAF), Latvia (IZM), Norway (RCN), Portugal (FCT), and Spain (AEI) in a joint action of JPI HDHL, JPI-OCEANS and FACCE-JPI launched in 2019 under the ERA-NET ERAHDHL (n° 696295). Francisca Rodrigues (CEECIND/01886/2020) is thankful for her contract financed by FCT/MCTES—CEEC Individual 2020 Program Contractinfo:eu-repo/semantics/publishedVersio