The Co-Inoculation Effect on Triticum aestivum Growth with Synthetic Microbial Communities (SynComs) and Their Potential in Agrobiotechnology.

The use of rhizospheric SynComs can be a new and sustainable strategy in the agrobiotechnology sector. The objective of this study was to create the most appropriate SynCom composition; examine the ability to dissolve natural rock phosphate (RP) from Morocco in liquid-modified NBRIP medium; determine organic acids, and phytohormones; and verify plant growth promoting and nutrition uptake effect in the pot experiments of winter wheat (Triticum aestivum). A total of nine different microorganisms were isolated, which belonged to three different genera: Bacillus, Pseudomonas, and Streptomyces. Out of the 21 treatments tested, four SynComs had the best phosphate-dissolving properties: IJAK-27+44+91 (129.17 mg L-1), IIBEI-32+40 (90.95 µg mL-1), IIIDEG-45+41 (122.78 mg L-1), and IIIDEG-45+41+72 (120.78 mg L-1). We demonstrate that these SynComs are capable of producing lactic, acetic, gluconic, malic, oxalic, citric acids, and phytohormones such as indole-3-acetic acid, zeatin, gibberellic acid, and abscisic acid. In pot experiments with winter wheat, we also demonstrated that the designed SynComs were able to effectively colonize the plant root rhizosphere and contributed to more abundant plant growth characteristics and nutrient uptake as uninoculated treatment or uninoculated treatment with superphosphate (NPK 0-19-0). The obtained results show that the SynCom compositions of IJAK-27+44+91, IIBEI-32+40, IIIDEG-45+41, and IIIDEG-45+41+72 can be considered as promising candidates for developing biofertilizers to facilitate P absorption and increase plant nutrition.

Application of whole-cell biosensors for analysis and improvement of L- and D-lactic acid fermentation by Lactobacillus spp. from the waste of glucose syrup production.

BACKGROUND: Lactic acid is one of the most important organic acids, with various applications in the food, beverage, pharmaceutical, cosmetic, and chemical industries. Optically pure forms of L- and D-lactic acid produced via microbial fermentation play an important role in the synthesis of biodegradable polylactic acid. Alternative substrates, including by-products and residues from the agro-food industry, provide a cost-effective solution for lactic acid production and are a promising avenue for the circular economy. RESULTS: In this study, the transcription factor (TF)-based whole-cell biosensor strategy was developed for the L- and D-lactic acid determination. It was cross validated with commonly used high-performance liquid chromatography and enzymatic methods. The utility of biosensors as an efficient analytical tool was demonstrated by their application for the lactic acid determination and fermentation improvement. We explored the ability of Lacticaseibacillus paracasei subsp. paracasei, Lactobacillus delbrueckii subsp. lactis, and Lactobacillus amylovorus to biosynthesize optically pure L-lactic acid, D-lactic acid or mixture of both from organic-rich residual fraction (ORRF), a waste of glucose syrup production from wheat starch. The fermentation of this complex industrial waste allowed the production of lactic acid without additional pretreatment obtaining yields from 0.5 to 0.9 Cmol/Cmol glucose. CONCLUSIONS: This study highlights the utility of whole cell biosensors for the determination of L- and D-forms of lactic acid. The fermentation of L-lactic acid, D-lactic acid and mixture of both by L. paracasei, L. lactis, and L. amylovorus, respectively, was demonstrated using waste of glucose syrup production, the ORRF.

The Biochemical Alteration of Enzymatically Hydrolysed and Spontaneously Fermented Oat Flour and Its Impact on Pathogenic Bacteria.

Avena sativa (A. sativa) oats have recently made a comeback as suitable alternative raw materials for dairy substitutes due to their functional properties. Amylolytic and cellulolytic enzyme-assisted modifications of oats produce new products that are more appealing to consumers. However, the biochemical and functional alteration of products and extracts requires careful selection of raw materials, enzyme cocktails, and technological aspects. This study compares the biochemical composition of different A. sativa enzyme-assisted water extracts and evaluates their microbial growth using spontaneous fermentation and the antimicrobial properties of the ferment extracts. Fibre content, total phenolic content, and antioxidant activity were evaluated using traditional methodologies. The degradation of A. sativa flour was captured using scanning electron microscopy (SEM); moreover, sugar and oligosaccharide alteration were identified using HPLC and HPLC-SEC after INFOGEST in vitro digestion (IVD). Additionally, taste differentiation was performed using an electronic tongue with principal component analysis. The oat liquid extracts were continuously fermented using two ancient fermentation starters, birch sap and Tibetan kefir grains. Both starters contain lactic acid bacteria (LAB), which has major potential for use in bio-preservation. In fermented extracts, antimicrobial properties against Gram-positive Staphylococcus aureus and group A streptococci as well as Gram-negative opportunistic bacteria such as Escherichia coli and Pseudomonas aeruginosa were also determined. SEM images confirmed the successful incorporation of enzymes into the oat flour. The results indicate that using enzyme-assisted extraction significantly increased TPC and antioxidant activity in both the extract and residues. Additionally, carbohydrates with a molecular mass (MM) of over 70,000 kDa were reduced to 7000 kDa and lower after the incorporation of amylolytic and cellulolytic enzymes. The MM impacted the variation in microbial fermentation, which demonstrated favourable antimicrobial properties. The results demonstrated promising applications for developing functional products and components using bioprocessing as an innovative tool.