Effect of culturing lactic acid bacteria with varying skim milk concentration on bacteria survival during heat treatment

Screening the Protective Agents Able to Improve the Survival of Lactic Acid Bacteria Strains Subjected to Spray Drying Using Several Key Enzymes Responsible for Carbohydrate Utilization

The aim of this study was to identify the most effective protectants for enhancing the viability of specific lactic acid bacteria (LAB) strains (Lactobacillus delbrueckii subsp. bulgaricus CICC 6097, Lactiplantibacillus plantarum CICC 21839, Lactobacillus acidophilus NCFM) by assessing their enzymatic activity when exposed to spray drying (inlet/outlet temperature: 135 °C/90 °C). Firstly, it was found that the live cell counts of the selected LAB cells from the 10% (w/v) recovered skim milk (RSM) group remained above 107 CFU/g after spray drying. Among all the three groups (1% w/v RSM group, 10% w/v RSM group, and control group), the two enzymes pyruvate kinase (PK) and lactate dehydrogenase (LDH) were more sensitive to spray drying than hexokinase (HK) and β-galactosidase (β-GAL). Next, transcriptome data of Lb. acidophilus NCFM showed that 10% (w/v) RSM improved the down-regulated expressions of genes encoding PK (pyk) and LDH (ldh) after spray drying compared to 1% (w/v) RSM. Finally, four composite protectants were created, each consisting of 10% (w/v) RSM plus a different additive-sodium glutamate (CP-A group), sucrose (CP-B group), trehalose (CP-C group), or a combination of sodium glutamate, sucrose, and trehalose (CP-D group)-to encapsulate Lb. acidophilus NCFM. It was observed that the viable counts of strain NCFM (8.56 log CFU/g) and enzymatic activity of PK and LDH in the CP-D group were best preserved compared to the other three groups. Therefore, our study suggested that measuring the LDH and PK activity could be used as a promising tool to screen the effective spray-dried protective agent for LAB cells.

Physiological changes in Rhodococcus ruber S103 immobilized on biobooms using low-cost media enhance stress tolerance and crude oil-degrading activity

For economic feasibility, sugarcane molasses (0.5%, w/v) containing K₂HPO₄ (0.26%, w/v) and mature coconut water, low value byproducts, were used in cultivation of Rhodococcus ruber S103 for inoculum production and immobilization, respectively. Physiological changes of S103 grown in low-cost media, including cell hydrophobicity, saturated/unsaturated ratio of cellular fatty acids and biofilm formation activity, enhanced stress tolerance and crude oil biodegradation in freshwater and even under high salinity (5%, w/v). Biobooms comprised of S103 immobilized on polyurethane foam (PUF) was achieved with high biomass content (10¹⁰ colony-forming units g^-1 PUF) via a scale-up process in a 5-L modified fluidized-bed bioreactor within 3 days. In a 500-L mesocosm, natural freshwater was spiked with crude oil (72 g or 667 mg g^-1 dry biobooms), and a simulated wave was applied. Biobooms could remove 100% of crude oil within only 3 days and simultaneously biodegraded 60% of the adsorbed oil after 7 days when compared to boom control with indigenous bacteria. In addition, biobooms had a long shelf-life (at least 100 days) with high biodegradation activity (85.2 ± 2.3%) after storage in 10% (w/v) skimmed milk at room temperature. This study demonstrates that the low-cost production of biobooms has potential for future commercial bioremediation.

Novel freeze-drying matrix for enhancing viability of probiotic supplemented milkshake during simulated in vitro digestion

Probiotics are recognized as essential components to improve health and regulate immune functions. Despite several probiotic formulations, the anticipation for non-fermented probiotic foods is noticeable. The objective of the study was to investigate and develop a stable freeze-dried synbiotic formula that can serve the purpose of a probiotic enricher as well as a thickener in an instant milk-based beverage. The freeze-dried synbiotic formula was assessed for the protective effect of whey protein-polysaccharides for retaining high cell viability during freeze-drying and subsequent storage. Highest survival rates were obtained for WP-15%I (85.90%), WP-15%P (85.43%), and WP-0.6%X (80.23%) combinations. During storage at 4 °C for 75 d, a lower specific rate of cell inactivation was found for WP-0.4%X (-0.0184 day^-1), WP-5%P (-0.0197 day^-1) and WP-5%I (-0.023 day^-1). Subsequent ingestion of synbiotic portions in the gastro-intestinal digestion simulator was studied in two ways to enumerate the retaining cell viability and understanding the importance of co-ingested food. Synbiotic portions reconstituted in milk showed higher probiotic survival through gastrointestinal digestion than water demonstrating the significance of supporting food matrix for improving the survival and efficiency of probiotics.

Optimization of the reproduction of Weissella cibaria in a fermentation substrate formulated with agroindustrial waste

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Use of pineapple and sacha inchi wastes in biotechnological processes.

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Valorization of agroindustrial waste in the context of circular economy.

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Use of alternative fermentation substrates (SFS) in the production of probiotics (Weissella cibaria), in order to substitute conventional substrates.

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Optimal conditions of the fermentation process for the reproduction and viability of W. cibaria.

Agroindustrial wastes contain macronutrients and micronutrients essential for the reproduction of lactic acid bacteria. In this research, the reproduction of Weissella cibaria was experimentally optimized in a supplemented fermentation substrate (SFS) formulated from pineapple and sacha inchi wastes. Response surface methodology was used to evaluate the influence of the following independent variables: temperature (32–40 °C), pH (5.0–6.0), and stirring speed (SS) (100–150 rpm) on the following dependent variables: viability (Log₁₀ CFU mL⁻¹), biomass production (B_Wc), lactic acid production (LA), biomass yield (Y_Bwc/S), biomass volumetric productivity (VP_Wc), LA volumetric productivity (VP_LA), carbon source consumption (CSC), N₂ consumption (N₂C), and specific growth rate (µ). The experimental optimization of multiple responses presented a desirability of 76.8%, thus defining the independent variables of the process: temperature = 35.1 °C, pH = 5.0, and SS = 139.3 rpm; and the dependent variables: viability = 10.01 Log₁₀ CFU mL⁻¹, B_Wc = 2.9 g L⁻¹, LA = 19.4 g mL⁻¹, Y_Bwc/S = 43.9 g biomass/g CSC, VP_Wc = 0.49 g L⁻¹h ^− 1, VP_LA = 3.2 g L⁻¹ h⁻¹, CSC = 17.2%, N₂C = 63.6% and µ = 0.28 h⁻¹. From these, viability, Y_Bwc/S, CSC, N₂C, and LA presented significant statistical differences, while the independent variable with the least important effect on the process was pH. Under optimal conditions of temperature, pH and SS; SFS favors the reproduction and viability of W. cibaria. This provides evidence of a sustainable alternative for the production of probiotics in the context of circular economy.