Selection criteria of lactic acid bacteria to be used as starter for sweet and salty leavened baked products

Honey characterization and identification of fructophilic lactic acid bacteria of fresh samples from Melipona beecheii, Scaptotrigona pectoralis, Plebeia llorentei, and Plebeia jatiformis hives

Stingless bees are essential to preser tropical ecosystems. They pollinate native flora, producing honey with properties for traditional health uses. Lactic acid bacteria spontaneously ferment honey in stingless bee honey (SBH). This study aims to determine the main physicochemical characteristics of Melipona beecheii, Scraptotrigona pectoralis, Plebeia jatiformis and Plebeia llorentei honey and to isolate and identify FLAB present in SBH samples. The physicochemical properties of SBH, such as color, pH, acidity, sugars, protein, total soluble solids, water activity, total polyphenols, and antioxidant activity, were determined since these parameters can be related to the presence of some bacteria groups, and with health benefits for humans and the hive ecosystems. FLAB harvested from honey, taken directly from storing pots of the hives, were identified by 16S ribosomal RNA sequencing and preserved for future biotechnological use due to their resistance to non-ionic osmotic stress. The results showed significant differences in the physicochemical characteristics of SBH samples. Seven FLAB from four stingless bee species were identified as Fructobacillus pseudoficulneus and F. tropaeoli. In addition, three other strains of Fructilactobacillus spp. were identified only at the genus level. All species showed the ability to grow under different carbon sources, resulting in negative hemolysis and sensitivity to cefuroxime, erythromycin, and chloramphenicol. To the best of our knowledge, this is the first time that the physicochemical and FLAB characterization of SBH from P. jatiformis and P. llorentei has been reported. Therefore, the future following research should be focused on the environmental, health and food biotechnological applications implications of FLAB from SBH.

Performance of Mixed-Microbial Culture from Civet Fecal Suspensions on Physicochemical Composition of Wet Fermented Arabica Coffee

This study aimed to evaluate the effects of mixed microbial culture from civet fecal suspension used as the inoculum for the fermentation of Arabica coffee. The type of Arabica coffee used for the research was the unpeeled coffee or the Arabica coffee cherries. Different proportion of inoculum introduced was thoroughly evaluated to assess the appropriate concentration of inoculum (0-40% inoculums represented in treatment 0-4 or T0 to T4) that would be applied to the fermentation of Arabica coffee cherries. Results revealed that treatment 4 (T4) containing 40% of the inoculum could degrade the sugar of the coffee beans faster than that of the other treatments in which within 24 hours of the incubation approximately 84% of the sugar was converted. T4 also reached the lowest caffeine content (1.8%) of the fermented coffee beans among other that of other treatments while the control had higher caffeine content (2.2%).This was substantially significant as the Arabica coffee cherries fermented with mixed microbial civet fecal suspensions can remarkably reduce the sugar and caffeine content of the Arabica coffee beans.

Fundaments and Concepts on Screening of Microorganisms for Biotechnological Applications. Mini Review

Microbial biotechnology uses microorganisms and their derivatives to generate industrial and/or environmental products that impact daily life. Modern biotechnology uses proteomics, metabolomics, quantum processors, and massive sequencing methods to yield promising results with microorganisms. However, the fundamental concepts of microbial biotechnology focus on the specific search for microorganisms from natural sources and their correct analysis to implement large-scale processes. This mini-review focuses on the methods used for the isolation and selection of microorganisms with biotechnological potential to empathize the importance of these concepts in microbial biotechnology. In this work, a review of the state of the art in recent years on the selection and characterization of microorganisms with a basic approach to understanding the importance of fundamental concepts in the field of biotechnology was carried out. The proper selection of isolation sources and the design of suitable selection criteria according to the desired activity have generated substantial changes in the development of biotechnology for more than three decades. Some examples include Taq polymerase in the PCR method and CRISPR technology. The objective of this mini review is to establish general ideas for the screening of microorganisms based on basic concepts of biotechnology that are left aside in several articles and maintain the importance of the basic concepts that this implies in the development of modern biotechnology.

Surface Layer Protein Pattern of Levilactobacillus brevis Strains Investigated by Proteomics

The outermost constituent of many bacterial cells is represented by an S-layer, i.e., a semiporous lattice-like layer composed of self-assembling protein subunits called S-layer proteins (Slps). These proteins are involved in several processes, such as protecting against environmental stresses, mediating bacterial adhesion to host cells, and modulating gut immune response. Slps may also act as a scaffold for the external display of additional cell surface proteins also named S-layer associated proteins (SLAPs). Levilactobacillus brevis is an S-layer forming lactic acid bacterium present in many different environments, such as sourdough, milk, cheese, and the intestinal tract of humans and animals. This microorganism exhibits probiotic features including the inhibition of bacterial infection and the improvement of human immune function. The potential role of Slps in its probiotic and biotechnological features was documented. A shotgun proteomic approach was applied to identify in a single experiment both the Slps and the SLAPs pattern of five different L. brevis strains isolated from traditional sourdoughs of the Southern Italian region. This study reveals that these closely related strains expressed a specific pattern of surface proteins, possibly affecting their peculiar properties.

Date Seeds Flour Used as Value-Added Ingredient for Wheat Sourdough Bread: An Example of Sustainable Bio-Recycling

Our study proposed date seeds flour (DSF) as an innovative ingredient for sourdough bread production through sustainable bio-recycling. We isolated autochthonous lactic acid bacteria and yeasts from DSF and DSF-derived doughs to build up a reservoir of strains from which to select starters ensuring rapid adaptation and high ecological fitness. The screening based on pro-technological criteria led to the formulation of a mixed starter consisting of Leuconostoc mesenteroides, Lactiplantibacillus plantarum, and Saccharomyces cerevisiae strains, which allowed obtaining a mature type I sourdough after consecutive refreshments, in which an aliquot of the durum wheat flour (DWF) was replaced by DSF. The resulting DSF sourdough and bread underwent an integrated characterization. Sourdough biotechnology was confirmed as a suitable procedure to improve some functional and sensory properties of DWF/DSF mixture formulation. The radical scavenging activity increased due to the consistent release of free phenolics. Perceived bitterness and astringency were considerably diminished, likely because of tannin degradation.

Sourdough Fermentation as a Tool to Improve the Nutritional and Health-Promoting Properties of Its Derived-Products

Cereal products are staple foods highly appreciated and consumed worldwide. Nonetheless, due to the presence of gluten proteins, and other co-existing compounds such as amylase-trypsin inhibitors and fermentable short-chain carbohydrates in those products, their preference by consumers has substantially decreased. Gluten affects the small gut of people with celiac disease, triggering a gut inflammation condition via auto-immune response, causing a cascade of health disorders. Amylase-trypsin inhibitors and fermentable short-chain carbohydrate compounds that co-exists with gluten in the cereal-based foods matrix have been associated with several gastrointestinal symptoms in non-celiac gluten sensitivity. Since the symptoms are somewhat overlapped, the relation between celiac disease and irritable bowel syndrome has recently received marked interest by researchers. Sourdough fermentation is one of the oldest ways of bread leavening, by lactic acid bacteria and yeasts population, converting cereal flour into attractive, tastier, and more digestible end-products. Lactic acid bacteria acidification in situ is a key factor to activate several cereal enzymes as well as the synthesis of microbial active metabolites, to positively influence the nutritional/functional and health-promoting benefits of the derived products. This review aims to explore and highlight the potential of sourdough fermentation in the Food Science and Technology field.

Yeasts and Lactic Acid Bacteria for Panettone Production: An Assessment of Candidate Strains

The recovery of yeasts and lactic acid bacteria (LAB) involved in sourdough fermentation is the first step in the selection of starters with suitable technological aptitude and capable of producing desired aromas and/or aromatic precursors. In this work, two sourdoughs samples (MA and MB) and the derived doughs (samples A and B) were collected from a bakery during artisanal Panettone manufacture. Yeasts and bacteria were isolated at different fermentation steps on selective agar media. A total of 77 isolates were obtained and characterized. Representative strains of yeasts and LAB were identified by sequencing the D1/D2 domain of the 26S rRNA and the 16S rRNA genes, respectively. Moreover, the volatile organic compounds (VOCs) produced in the collected samples were detected and correlated to the species found in the same samples. The results highlighted the occurrence of Kazachstania humilis in both samples A and B, while Saccharomyces cerevisiae strains were detected only in samples B. Among LAB, Fructilactobacillus sanfranciscensis was the main species detected in both sourdoughs. Furthermore, strains belonging to the species Lactiplantibacillus plantarum, Furfurilactobacillus rossiae, Lactobacillus parabuchneri, Leuconostoc citreum, and Leuconostoc mesenteroides were assessed in the dough samples.

Bacteria do it better! Proteomics suggests the molecular basis for improved digestibility of sourdough products

The aim of this study was to evaluate the dynamics of proteolysis during dough fermentation started with different lactic acid bacteria species, through the identification of intermediate and small-sized peptides generated during fermentation. Single-strain cultures of Levilactobacillus brevis, Fructilactobacillus sanfranciscensis, Companilactobacillus alimentarius, and Leuconostoc pseudomesenteroides were assayed as sourdough starters. Assays were carried out at lab-scale for 48 h of fermentation, using both unstarted and yeast-leavened dough as controls. Physicochemical and microbiological analyses were combined with peptidomic and proteomic profiling, identifying several hundreds of peptides mainly released from the water-soluble wheat proteins, including β-amylase, triticin, and serpins. Both α- and γ-gliadins were hydrolyzed, though only at the N-terminal domain, while the central protein region - encrypting celiac disease epitopes- remained unaffected. The bacterial-mediated consumption of sugars and the concomitant hydrolysis of starch degrading β-amylase could underlie improved digestibility and several nutritionally beneficial effects of sourdough baked products.