Free Bacteria Research Articles

Integrated electro-coagulation and gravity driven ceramic membrane bioreactor for roofing rainwater purification: Flux improvement and extreme operating case

The collected roofing rainwater with high water quality and large water volume, can alleviate the crisis of water resources and fit the Low-Impact Development (LID) concept. In this work, a novel water purification technology, Electro-Coagulation coupled with Gravity-Driven Ceramic Membrane Bio-Reactor (EC-GDCMBR) was developed for the roofing rainwater purification under long-term operation (136 days). EC-GDCMBR system not only exhibited the better effluent quality, but also obtained the greater flux (~32 LMH). The reason contributed to the high permeability of ceramic membrane and large porosity of biofilm formed by floc growth (~36 μm) during the EC process, which was also proved by SEM image. The coagulation, adsorption, biodegradation, and coprecipitation of EC-GDCMBR was able to synergistically remove the particulate matter, ammonia nitrogen (NH3-N), Total Phosphorus (TP), organic substances, and heavy metal (i.e., Cr, Zn, and Cu). In particular, via the analysis of bacterial abundance, Extracellular Polymeric Substances (EPS), Assimilable Organic Carbon (AOC), Adenosine Tri-Phosphate (ATP) and Confocal Laser Scanning Microscopy (CLSM), EC could sweep most free bacteria on the ceramic membrane surface, enhancing the biological purification efficiency. Furthermore, a large amount of Pseudomonas (12.4 %-66.7 %) and Nitrospira (1.46 %-3.16 %) in the aggregates formed the biofilms, improved the NH3-N removal. During the long-term operation, there are some unavoidable problems, such as the thick and ripened biofilm of EC-GDCMBR would crack and fall off. Based on this, the current work also studied the reliability of GDCMBR under “extreme operating case”, and the results showed that neither the biofilm detachment nor the biofilm breakup had a significant impact on the effluent quality. Overall, the findings of this study suggest the reliability of EC-GDCMBR for the sustainable operation of roofing rainwater purification and improve the application value of decentralized rainwater harvest device.

Mechanisms underlying enhanced bioremediation of sulfamethoxazole and zinc(II) by Bacillus sp. SDB4 immobilized on biochar

Microbial remediation is an eco-friendly and promising approach for the decontamination of wastewater containing sulfamethoxazole (SMX) and Zn2+. However, free bacteria are sensitive to environmental variation, limiting the application. In this study, biochar-immobilized Bacillus paramycoides SDB4 (ISDB4) was used to overcome the disadvantages. The results showed that the removal by ISDB4 was significantly increased under different pH conditions and initial combined contaminant concentrations. Notably, at pH 7, SMX (20 mg L−1) and Zn2+ (100 mg L−1) were completely removed by ISDB4, and their levels were 29.28% and 92.34% higher than that of SDB4, respectively. Besides, ISDB4 showed excellent reusability with 43.24% of SMX and 50.34% of Zn2+ removal efficiencies after five continuous cycles. Such improvements might be related to enhanced biotransformation of SMX from 45.81% with SDB4 to 89.98% with ISDB4. Compared with SDB4, the contributions of ion exchange and complexation of ISDB4 with Zn2+ increased by 9.53% and 6.72%, respectively. In case of ISDB4, SEM-EDS and FTIR showed that biochar provided sufficient space for the attachment and proliferation of SDB4, and the removal of combined contaminants was enhanced by SDB4 due to the presence of functional groups and light metals on biochar. This study provides a green and effective strategy for the bioremediation of antibiotic and heavy metal co-contaminated aquaculture wastewater.

Influence of encapsulation on the survival of probiotics in food matrix under simulated stress conditions

The main objective of the present study was to evaluate the influence of encapsulation by extrusion technique using two hydrogels, namely; sodium alginate (Na-ALG) and whey protein isolate (WPI) on Bifidobacterium bifidium viability and stability of yoghurt under simulated gastrointestinal conditions. Probiotic bacteria (free or encapsulated) were added to yogurt for four weeks to test their viability and stability. Physicochemical and sensory analysis of yoghurt were conducted. Viability of B. bifidium in the simulated gastrointestinal conditions pH 2 and pH 7.5 was determined. Also, the efficiency of encapsulated final yield of the microcapsules was determined. With storage time, the pH of yoghurt containing encapsulated bacteria increased more than that of yoghurt containing free probiotic bacteria, resulting in a decrease in acidity. When compared to yoghurt containing encapsulated bacteria, the lactose level of yoghurt containing free probiotic bacteria decreased over time. The viscosity of yoghurt containing encapsulated WPI remained stable over the storage period, with syneresis remaining stable. The sensory properties of yoghurt containing free probiotics deteriorated over time. Cell viability was significantly reduced in yoghurt-containing free probiotics compared to other treated yoghurts. Cell viability in free probiotics yoghurt was lower than in encapsulated ones when exposed to simulated gastric and intestinal juice. In conclusion, WPI- encapsulated probiotics showed better stability over 28 days of storage in both yoghurt and gastrointestinal conditions, followed by sodium alginate.

Investigation of the effect of microplastics on the UV inactivation of antibiotic-resistant bacteria in water

This study investigated the effect of polyethylene and polyvinyl chloride microplastics on the UV fluence response curve for the inactivation of multidrug-resistant E. coli and enterococci in ultrapure water at pH 6.0 ± 0.1. In the absence of microplastics, the UV inactivation of the studied bacteria exhibited an initial resistance followed by a faster inactivation of free (dispersed) bacteria, while in the presence of microplastics, these 2 regimes were followed by an additional regime of slower or no inactivation related to microplastic-associated bacteria (i.e., bacteria aggregated with microplastics resulting in shielding bacteria from UV indicated by tailing at higher UV fluences). The magnitude of the negative effect of microplastics varied with different microplastics (type/particle size) and bacteria (Gram-negative and Gram-positive). Results showed that when the UV transmittance of the microplastic-containing water was not taken into account in calculating UV fluences, the effect of microplastics as protectors of bacteria was overestimated. A UV fluence-based double-exponential microbial inactivation model accounting for both free and microplastic-associated bacteria could describe well the disinfection data. The present study elucidated the effect of microplastics on the performance of UV disinfection, and the approach used herein to prove this concept may guide future research on the investigation of the possible effect of other particles including nanoplastics with different characteristics on the exposure response curve for the inactivation of various microorganisms by physical and chemical disinfection processes in different water and wastewater matrices.

Millifluidic-assisted ionic gelation technique for encapsulation of probiotics in double-layered polysaccharide structure

A unique double-layered vehicle was fabricated for the first time based on a millifluidic/direct gelation to encapsulate probiotics. Free probiotic bacteria are usually very sensitive to severe gastrointestinal conditions and maintaining their survival when passing through the digestive tract is essential. The effects of alginate concentration (20–30 g/L), flow rates of alginate (0.8–1.2 mL/min), and W/O emulsion (0.5–0.7 mL/min) on encapsulation efficiency (EE), size, and sphericity of core–shell millicapsules were optimized for encapsulation of Bifidobacterium animalis subsp. lactis and Lactobacillus plantarum. The optimized calcium-alginate millicapsule was spherical (0.97 ± 0.01 SF), with an average diameter of 4.49 ± 0.19 mm, and encapsulation efficiency of 98.17 ± 0.5 %. Two strains were encapsulated separately in W/O emulsion as a core of the millicapsule. After coating with chitosan, the encapsulation yield of the bacteria, survival rates under simulated gastrointestinal (GI) conditions, and viability during storage were determined. Survival efficiency of B. animalis subsp. lactis and L. plantarum after millifluidic encapsulation were found to be 92.33 and 90.81 %, respectively. Cell viability of encapsulated probiotics after passing through the GI system was improved (7.5 log CFU mL−1 for both strains). Although the viability of the encapsulated probiotics stored at −18 °C for five months significantly decreased (p<0.05), the number of live cells was approximately in accordance with the standard definition of long-term probiotic survival (6 log CFU/g). This work provides a pathway for the construction of an innovative delivery system with high efficiency and protective effects for probiotics.

Self-healing cement composites based on bleaching earth immobilized bacteria

Crack formation is inevitable on the surface of the cement-based material, considerably leading to shortening service life. A sustainable self-healing technique based on microbial induced calcite precipitate (MICP) is recognized as a promising solution to increase durability and prevent structural failure. This research investigated the potential of bleaching earth immobilized bacteria incorporated normal and glass fiber mortars to enhance autogenous crack-healing ability. The viability of immobilized bacteria in the cement slurry and the influence of self-healing agents on the mechanical strength of mortar were examined first. The crack healing efficiency was evaluated by comparing the recovery of watertightness, the crack width and area healing ratio. Experimental results showed that the permeability coefficient of the specimens with immobilized bacteria (77.4%–93.3%) decreased more than in those with free bacteria (10.1%–12.6%). The maximum crack width healed and fracture area repair ratio were 0.44 mm and 96%, respectively. The crack healing compounds was calcite crystals with dense accumulation according to X-ray diffraction and scanning electron microscopy. This crack healing method from inside to outside has important guiding significance for the sustainable development of cement-based materials.

Preparation of Micron-Scale Activated Carbon-Immobilized Bacteria for the Adsorption–Biodegradation of Diesel Oil

This paper investigated the micron-scale activated carbon (MAC) immobilized diesel-oil-degrading bacteria (bio-MAC) used as remediation materials for the removal of diesel-oil-contaminated water. The high-efficiency indigenous diesel-oil-degrading bacteria were firstly screened and enriched, then the MAC was used as a diesel oil sorbent and biocarrier for the immobilization of degrading bacteria to prepare the bio-MAC material. The removal performance of the bio-MAC was evaluated via a comparison with the freely degrading bacteria and MAC. The SEM results demonstrated that the diesel-oil-degrading bacteria were effectively immobilized and grew well on the surfaces of MAC particles. The concentration of MAC significantly influenced the growth and activity (DHA and LPS) of immobilized bacteria, and the MAC addition of 3.0 g/L was proven to be an optimum amount for the preparation of bio-MAC. The high-throughput sequencing analysis further indicated that the bacteria immobilized on MAC showed higher abundance levels and diversities index values compared to freely suspended bacteria, such as Pseudomonas, Rhodococcus, Bacillus and Microbacterium. The FTIR spectroscopy results showed that the bio-MAC could effectively degrade the aliphatic hydrocarbons, alkenes and aromatic compounds of diesel oil to carboxylic acids, esters, alcohols and other metabolites. When the concentration of diesel oil was 1 g/L, the removal efficiency for the diesel oil of bio-MAC reached 86.35% after 15 days, while only 23.82% and 70.97% of the diesel oil was removed using the same amount of free bacteria and MAC, respectively. The prepared bio-MAC showed a synergic effect of adsorption and biodegradation and efficiently removed diesel oil from wastewater.

Bio-Precipitation of Calcium Ions Induced by Free and Immobilized Virgibacillus dokdonensis WLR1 in Hypersaline Wastewater

Hypersaline wastewater has been widely used in industrial processes in some countries short of freshwater, but calcium ions in such wastewater should be removed due to the danger of limescale being produced. In this study, calcium ions in hypersaline (sodium chloride: 5%) wastewater was biomineralized into different carbonate minerals under the action of free and immobilized Virgibacillus dokdonensis WLR1 bacteria. The results show that the calcium ion precipitation rate was much higher under the conditions of immobilized bacteria (p < 0.01), and that there was a significant difference in the mineral phases, the diversity of protein secondary structures and morphologies, and chemical characteristics of the mineral surfaces between the free and the immobilized bacteria based on XRD, FTIR, SEM-EDS, and XPS analyses. TG, DTG, and DSC results show that with increasing calcium ion concentrations, the thermal stability of calcium carbonate under the conditions of free bacteria decreased due to the decline in crystallinity. The stable carbon isotope values (δ13CPDB) of calcium carbonate formed by free bacteria changed from −16.80‰ to −18.17‰; the much more negative δ13CPDB values suggest that the calcium carbonate minerals are biotic. From ultrathin slices analyzed by HRTEM-mapping-SAED, it was observed that calcite is formed inside the cell, thus also facilitating calcium ion removal. Research concerning intracellular calcite has rarely been reported. This study helps to further understand the mechanisms of biomineralization, and also provides an environmentally friendly method to remove calcium ions from hypersaline wastewater.

The potential effectiveness of mixed bacteria-loaded biochar/activated carbon to remediate Cd, Pb co-contaminated soil and improve the performance of pakchoi plants

Cadmium (Cd) and lead (Pb) are toxic heavy metals that cause severe soil pollution and pose health risks to humans. It is urgent to develop feasible strategies for Pb and Cd remediation. In this study, a bacteria consortium (Enterobacter asburiae G3, Enterobacter tabaci I12 and Klebsiella variicola J2 in a 1:3:3 proportion) with optimal Cd, Pb adsorption ability was constructed and immobilized on biochar (BC)/activated carbon (AC) via physisorption and sodium alginate encapsulation. The effects of mixed bacteria-loaded BC/AC on Cd and Pb remediation were investigated. The results indicated that their application reduced the DTPA-extractable Cd, Pb in soil by 22.05%−55.84% and 31.64%−48.13%, respectively. The residual Pb, Cd were increased while the exchangeable fractions were decreased. Soil urease, catalase and phosphatase activities were enhanced and soil bacterial community was improved, indicating a soil quality improvement. Consequently, the biomass of pakchoi plants was significantly increased. Cd and Pb in the shoots of pakchoi plants were decreased by 28.68%−51.01% and 24.18%−52.87%, respectively. Collectively, the bacteria-loaded BC/AC showed superior performance than free bacteria, BC and AC alone. Our study may provide a better understanding of the development of green and sustainable materials for remediation of heavy metal by the combination of BC/AC and functional bacteria.

Graphene oxide and mineralized collagen-functionalized dental implant abutment with effective soft tissue seal and romotely repeatable photodisinfection.

Grasping the boundary of antibacterial function may be better for the sealing of soft tissue around dental implant abutment. Inspired by ‘overdone is worse than undone’, we prepared a sandwich-structured dental implant coating on the percutaneous part using graphene oxide (GO) wrapped under mineralized collagen. Our unique coating structure ensured the high photothermal conversion capability and good photothermal stability of GO. The prepared coating not only achieved suitable inhibition on colonizing bacteria growth of Streptococcus sanguinis, Fusobacterium nucleatum and Porphyromonas gingivalis but also disrupted the wall/membrane permeability of free bacteria. Further enhancements on the antibacterial property were generally observed through the additional incorporation of dimethylaminododecyl methacrylate. Additionally, the coating with sandwich structure significantly enhanced the adhesion, cytoskeleton organization and proliferation of human gingival fibroblasts, which was effective to improve soft tissue sealing. Furthermore, cell viability was preserved when cells and bacteria were cultivated in the same environment by a coculture assay. This was attributed to the sandwich structure and mineralized collagen as the outmost layer, which would protect tissue cells from photothermal therapy and GO, as well as accelerate the recovery of cell activity. Overall, the coating design would provide a useful alternative method for dental implant abutment surface modification and functionalization.

Development of a functional chocolate using gamma-amino butyric acid producer Lacticaseibacillus rhamnosus NRRL B-442

The human microbiota is influenced by the immune and nervous systems of the host. Gamma-aminobutyric acid (GABA) is known as bioactive compound and it has important physiological functions, such as anti-hypertensive and antidepressant activities. Lactic acid bacteria (LAB), especially Lactobacillus species are known as the most important GABA producers because of the food-grade nature. The purpose of this study is to develop a functional chocolate using microencapsulated GABA producer Lacticaseibacillus rhamnosus NRRL B-442 strain for patients having an anxiety disorder.Water-in-oil emulsion technique was conducted for microencapsulation using whey-pullulan complex. Microencapsulated and free L. rhamnosus cell counts were 6.75 and 7.20 log CFU/g in chocolates, respectively, at the end of 60 days. During simulated in vitro digestion analysis, survival rate of microencapsulated bacteria in chocolate samples was found at higher percentage (87%) than free bacteria (75%). Furthermore, microencapsulated L. rhamnosus did not affect the physical, chemical, and sensory properties of chocolate.Consequently, L. rhamnosus with the highest GABA producing capability may provide insight for an anxiety disorder patient, since this strain has been thought as having a therapeutic effect. A new functional food model was developed for “GutBrain Axis” phenomena since the chocolate could be accepted as a good carrier for GABA producer bacteria.

Calcium ion biorecovery from industrial wastewater by Bacillus amyloliquefaciens DMS6

Calcium ions in industrial wastewater needs to be removed to prevent the production of limescale, which can have negative consequences. Biomineralization has become the focus due to its lower costs than traditional methods of remediation. In this study, calcium ions were bio-precipitated under the action of free and immobilized Bacillus amyloliquefaciens DMS6 bacteria, and the calcium ion removal efficiency was also compared. The results show that it only needed 3 days to decrease the calcium ion concentration to an ideal level of 76-116 mg/L under the action of DMS6 bacteria immobilized by activated carbon fiber, with calcium ion removal ratios reaching 99%-95% by the 7th day. DMS6 bacteria immobilized by activated carbon fiber were superior to free bacteria and bacteria immobilized by sodium alginate in calcium ion removal. Calcium ions are biomineralized into calcite, Mg-rich calcite, aragonite and monohydrocalcite with abundant organic functional groups, 4 types of secondary protein structures, amino acids, phospholipids, negative stable carbon isotope δ13CPDB values (-16.68‰ to-17.25‰) and negatively charged biomineral surface. Calcium ions were diffused into cells and took part in the intracellular biomineralization of monohydrocalcite, also facilitating calcium ion removal. The formation of intracellular monohydrocalcite has rarely been reported. This study demonstrates an economic and environmentally friendly method to remove calcium ions from industrial wastewater.

Potential Use of Moringa oleifera Twigs Extracts as an Anti-Hyperuricemic and Anti-Microbial Source

Moringa oleifera (MO) grows throughout most of the tropics and has several industrial and medicinal uses. Besides the various uses of the plant parts such as its leaves, seed kernels, roots, or stem barks, the twigs (MT) of this plant are usually regarded as excessive parts. Although there have been few studies conducted to determine the value of this plant part, in fact, its potential uses—especially the pharmaceutical effects—of this biomaterial remains an up-to-date topic for scientists to discover due to the lack of interest so far. This study aims to identify the optimized fractions of different solvents for the extraction of antioxidants, for xanthine oxidase inhibition agents, and for anti-microbial activities. The two most active fractions obtained by column chromatography were the Hexane-Ethyl Acetate elution at a 9:1 (E1) and 8:2 (E2) ratio, respectively. With regard to antioxidant activity, E1 and E2 displayed relatively high DPPH radical scavenging capacity (IC50 = 87.7 and 99.0 µg/mL), which was only four times weaker than the control BHT (IC50 = 21.4 µg/mL). The highest inhibition activity against xanthine oxidase was also observed clearly in E1 and E2, which showed relatively low IC50 (54.7 and 42.0 µg/mL, respectively). These levels were inconsiderably higher than that of the positive control (IC50 = 20.8 µg/mL), proving that E1 and E2 exerted relatively strong antioxidant activity in terms of XOD inhibition. Regarding the antimicrobial test, E2 showed the highest inhibition activities against E. coli, K. pneumoiae, L. monocytogenes, B. subtilis, and P. mirabilis. The result indicates that (1) E1 and E2 were the strongest fractions for constraining free radical agents and several bacteria, and thus, (2) Moringa oleifera twigs are also a potential source for the prevention of gout-related symptoms.

A Novel Route for Double-Layered Encapsulation of Streptomyces fulvissimus Uts22 by Alginate–Arabic Gum for Controlling of Pythium aphanidermatum in Cucumber

Damping-off disease due to Pythium aphanidermatum is one of the most harmful diseases of cucumber. One of the critical issues in the field of biological control is the establishment of a link between the beneficial bacteria screened in the laboratory and its industrial application. Therefore, when developing biocontrol agents, it is necessary to study the optimization of mass production conditions and to select a suitable carrier for their final formulation. In this study, an attempt was made to provide a suitable formulation for a Streptomyces fulvissimus Uts22 strain based on alginate–Arabic gum and nanoparticles (SiO2 and TiO2) with a layer-by-layer technique. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) studies showed that when Arabic gum was added to the composition, an electrostatic interaction occurred between alginate and Arabic gum. The scanning electron microscope image of beads show a cubic shape and good dispersion of microcapsules. The encapsulation efficiency in the prepared formulation was reported to be 94%. The maximum release of bacteria from the capsule was recorded on the 35th day of storage, about 109 CFU/gr. The greenhouse experiments showed that encapsulated bacteria resulted in a 95% reduction in damping-off disease of cucumber and showed more potential effects on increasing plant growth traits than free bacteria. This encapsulation strategy can be considered as a suitable alternative for future applications in the agricultural field.

Immobilization of Ochrobactrum sp. on Biochar/Clay Composite Particle: Optimization of Preparation and Performance for Nitrogen Removal.

The objective of this study was to prepare biochar/clay composite particle (BCCP) as carrier to immobilize Ochrobactrum sp. to degrade ammonia nitrogen (NH4+-N), and the effects of calcined program and immobilizing material were investigated. Results reflected that the parameters were as follows: calcined temperature 400°C, heating rate 20°C min–1, and holding time 2 h, and the adsorption capacity could reach 0.492 mg g–1. Sodium alginate/polyvinyl alcohol, as embedding material, jointed with NH4+-N adsorption process and then degraded by Ochrobactrum sp. with 79.39% degradation efficiency at 168 h. Immobilizing Ochrobactrum sp. could protect strain from high salt concentration to achieve the exceeding degradation efficiency than free bacteria, but could not block the impact of low temperature.

Electrospinning polyacrylonitrile (PAN) based nanofiberous membranes synergic with plant antibacterial agent and silver nanoparticles (AgNPs) for potential wound dressing

Polyacrylonitrile (PAN) nanofiberous membranes incorporated with different content of Curcumin (Cur), tannic acid and silver nanoparticles (AgNPs) were successfully fabricated by an electrospinning process. The analytical results from the characterizations including scanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and ultraviolet-visible photometry (UV–vis) exhibited good physicochemical properties for the obtained novel electrospun composite membranes. The nanofibers exhibited smooth surface with diameter ranged between 375 and 450 nm. The AgNPs obtained by TA reduction owned an average particle diameter of 19.1 nm. There was a rapid release of AgNPs in the Cur/TA/AgNPs/PAN electrospun composite membranes within 8 h, and then a relatively stable release of AgNPs after 24 h. Sustained drug release tests on Cur revealed that the samples exhibited an initial burst response for the first 24 h, followed by sustained release for up to 192 h, which could be traced by fluorescence to observe changes of Cur. The obtained electrospun Cur/TA/AgNPs/PAN nanofiberous composite membrances exhibited better hydrophilicand positive antimicrobial properties. It was found that thoseelectrospun Cur/TA/AgNPs/PAN nanofiberous composite membrances could rapidly scavenge DPPH radicals within 120 s. The results from in vitro cell compatibility test that normal growth and proliferation of Bone marrow MSCs were noticed on the fiber surface within 5 days, indicating favorable biocompatibility. this novel electrospun Cur/TA/AgNPs/PAN nanofiberous composite membranes can be potentially used as the wound dressing in prevention of free radicals and bacteria to wounds.

Purposely Development of the Adaptive Potential of Activated Sludge from Municipal Wastewater Treatment Plant Focused on the Treatment of Landfill Leachate

Biological treatment is a key technology in landfill leachate treatment However, often its efficiency is not high enough due to the pollutants in concentrations above the critical ones. The present study aimed to investigate the adaptive responses that occur in activated sludge (AS) during landfill leachate purification. A model process with AS from a municipal wastewater treatment plant and landfill leachate in increasing concentrations was constructed. The data showed that when dilutions 25 and 50 times had been applied the structure of the AS was preserved, but the COD cannot be reduced below 209 mg O2/L. The feed of undiluted leachate destroyed the AS structure as SVI was reduced to 1 mL/g, biotic index to 1, floc size was greatly reduced and COD remained high (2526 mg O2/L). The dominant group of protozoa was changed from attached to free-swimming ciliates. An increase of the bacterial groups responsible for the xenobiotics elimination (aerobic heterotrophs, genera Pseudomonas, Acinetobacter, Azoarcus, Thauera, Alcaligenes) was registered. This was accompanied by a significant increase in free bacteria. The obtained data showed that for optimal treatment of this type of water it is necessary to include a combination of biological treatment with another non-biological method (membrane filtration, reverse osmosis, etc.).

An edible erodible semi‐interpenetrating polymer network as a microcapsule shell to protect probiotic bacteria during reconstitution of powdered infant formula at elevated temperatures

AbstractProbiotic bacteria (PB) are added to some powdered infant formula (PIF) to fortify their composition and to make them more similar to human breast milk. However, the effectiveness of the probiotics may disappear when PIF is reconstituted at 70°C according to the WHO guidelines designated to destroy possible contaminants. We present a unique microencapsulation technique to effectively protect Bifidobacterium breve M‐16 V (B. breve) during the reconstitution process at 70°C, to enable their incorporation into PIF. The microcapsules were prepared by a wet granulation process to encompass the bacteria within a core matrix which was subsequently coated by two consecutive protective layers including an edible erodible semi‐interpenetrating polymer network (IPN) as the outer layer. The semi‐IPN sample films and the final microcapsules were characterized using different analytical methods. The survival of the microencapsulated bacteria during reconstitution in hot water (70°C) was evaluated and compared to that of the free bacteria. While the viability of the free bacteria was significantly reduced during the reconstitution process, the microencapsulated bacteria maintained high viability. The degree of PB protection was strongly influenced by the structure of the microcapsules, the composition and thickness of the semi‐IPN layer, and the content of the bacteria.

Yoghurt Production Potential of Lactic Acid Bacteria Isolated from Leguminous Seeds and Effects of Encapsulated Lactic Acid Bacteria on Bacterial Viability and Physicochemical and Sensory Properties of Yoghurt

This study aims to determine the yoghurt production potential of lactic acid bacteria isolated from legumes seeds (lentils, beans, cowpea, and broad beans) and examine the effects of alginate capsules of selected starter cultures with high yoghurt production potential on the physicochemical properties, sensory properties of yoghurt, and bacterial viability during storage time at 4°C. The exopolysaccharide (EPS), proteolytic activity, and acidification properties of eight different isolates were determined, and sixteen different yoghurt combinations prepared. The samples showed similar physicochemical (pH, titratable acidity, dry matter, and whey separation), bacterial count, and sensory results in comparison with the commercial yoghurt used as a control sample. The acidity and pH of the yoghurt samples were significantly affected by the storage time. Total solids of yoghurt samples generally tend to decrease and syneresis of yoghurt samples also differed for each starter culture combination during the storage time. The total count of lactic acid bacteria during the storage time was higher than 107 CFU/g. The sensory analysis results of bacterial combinations are significantly different ( p &lt; 0.05 ). Results indicated that isolated starter cultures have potential as commercial starters to improve the quality of yoghurt. Selected starter cultures with yoghurt production potential were encapsulated. Lactic acid bacteria with encapsulation efficiency of 86,3 ± 0,2 and 82,26 ± 0,79 were selected for yoghurt production. The physicochemical properties of the yoghurt with free and encapsulated starter culture were significantly different during the storage time. The reduction (∼0,5 log cfu/g) in the numbers of free and encapsulated starter cultures is over during the storage time ( p &lt; 0.05 ). The acceptability of yoghurt containing encapsulated bacteria was lower than the yoghurt containing free bacteria by the panelists. Consequently, it was determined that alginate capsules increased bacterial viability, but the sensory properties of yoghurt were affected adversely. The LAB isolated form legumes can be introduced to the national microbial collection.

Improvement of the quality parameters of a novel synbiotic yogurt sauce using microencapsulated Lactobacillus paracasei and natural prebiotics

This study aimed to examine the production of a synbiotic yogurt sauce and to evaluate its physicochemical, microbiological, sensory, and rheological properties during storage. Lactobacillus paracasei was microencapsulated with resistant starch and sodium alginate by the emulsion technique. Two forms of probiotic bacteria (microencapsulated and free), together with prebiotic compounds (flaxseeds and chia seeds each one at two concentrations of 2% and 4%), were added to the yogurt sauce. Samples were kept for 30 days at 4 ˚C and observed for physicochemical, microbiological, sensory, and rheological characteristics within specific intervals. The results revealed that the produced synbiotic yogurt sauce was characterized as a pseudoplastic fluid. However, its viscosity increased due to the presence of flaxseeds and chia seeds. The addition of flaxseeds and chia seeds improved the survival of bacteria. The post-acidification values were lower in samples containing the microencapsulated bacteria compared to samples containing the free bacteria. Among the produced samples, the highest acceptable score for the sensory characteristic was obtained for the sample containing microencapsulated L. paracasei and 2% flaxseeds. Therefore, it is possible to produce a synbiotic yogurt sauce with desirable properties.