Microbial Viability Research Articles

Effects of the applied voltage on electroactive microbial biofilm viability and hydrogen production in a recalcitrant organic waste-fed single-chamber membrane-free microbial electrolysis cell performance

The microbial electrolysis cell (MEC) is a future clean technology with a wide range of applications in energy recycling fields, particularly for hydrogen production. Applied voltage governs the electrochemically active microbial activities in MEC and further affects hydrogen production. Therefore, this study investigated the impacts of the applied voltages on MEC performance and anodic biofilm viability during the biotransformation of straw waste biomass into green hydrogen energy in an anaerobic environment. The results revealed that the COD removal efficiency and bioH2 yield increased with the augmentation of the applied voltage and beyond 0.8 V started decreasing. Among the performed protocols MEC0.8 depicted the best performance with a maximum H2 production of 6.017 mmoles H2/g-COD which was ∼28.2 % and ∼9.8 % higher than that of MEC0.5 and MEC1.0 respectively. Moreover, it also achieved a maximum COD removal of 73.4% and a coulombic efficiency (CE) of 68.4%. Consistently, the anodic biofilm viability and bacterial cell shape in the MECs performed with 0.5 V and 0.8 V were less affected but largely damaged in a high potential operated protocol (MEC1.0), suggesting that the mixed electroactive consortia were so sensitive to high potentials. Furthermore, MEC1.0 displayed a high charge transfer resistance of 16.06 Ω which was ∼22.1 %, and ∼73.7 % higher than that of MEC0.8, and MEC0.5 respectively. Based on our novel study’s results, the optimal applied voltage for the best performance of MEC was 0.8 V; and this information will be a pillar for future MEC operations prior to maintaining its industrial practice.

Optimization of operating parameters for spraying microbial (Bacillus thuringiensis and Beauveria bassiana) based bio-pesticide solutions for foliar application

Exposure to mechanical stresses developed due to different components of spraying system may cause permanent damage to the microbes of bio-pesticide solutions. To achieve maximum effectiveness of spray application, proper selection of nozzle size and operating pressure is critical. Two different classes of bio-pesticides viz. bacterial-based Bacillus thuringiensis (BBP solution) and fungal-based Beauveria bassiana (FBP solution) were evaluated for spray application by three hollow cone nozzles (1.14, 2.35 and 3.56 mm in diameter) at four operating pressures (145, 245, 345 and 445 kPa). It was observed that viability of bio-pesticide solutions increases with decrease in operating pressure and increase in nozzle size. The nozzle orifice diameter and operating pressure of the spraying system were optimized to get desired application rate, volume median diameter (VMD) and coefficient of variation (CV) of spray for maximum microbial viability of bio-pesticide solutions. The optimized values of application rate (323.94-and 325.58 L ha−1), VMD (225.88 and 231.89 µm), CV (84.49 and 85.99%) and viability (6.63 × 106 and 6.06 × 106 cfu ml−1) were obtained for BBP and FBP solutions, respectively at nozzle orifice size of 3.56 mm and 145 kPa operating pressure.

Colloidal copper oxide nanoparticles leading to a biphasic dose-response in growth inhibition of Staphylococcus aureus.

Aim: The dose response in growth inhibition of Staphylococcus aureus treated with colloidal copper oxide nanoparticles (CuO-NP) was evaluated. Methods: An in vitro microbial viability assay was conducted with CuO-NP concentrations spreading over the 0.4-848.0μg/ml range. The dose-response curve was modeled with a double Hill equation. UV-Visible absorption and photoluminescence spectroscopies allowed tracking concentration-dependent modifications in CuO-NP. Results: Two specific phases separated by the critical concentration of 26.5μg/ml were observed in the dose-response curve, with each exhibiting proper IC50 parameters, Hill coefficients and relative amplitudes. Spectroscopy techniques reveal the occurrence of aconcentration-triggered aggregation of CuO-NP starting from this critical concentration. Conclusion: The findings demonstrate a dose-related change in S. aureus sensitivity to CuO-NP, which probably arises from the aggregation of this agent.

A Systematic Review: Current Technology of Solid Carrier Formulation to Improve Viability and Effectiveness of Nitrogen-Fixing Inoculant

Biofertilizers are a promising alternative solution to reduce the long-term adverse effects of chemical fertilizers and are increasingly important for promoting sustainable agriculture. Unfortunately, biofertilizers have a relatively short shelf life, and microbial effectiveness often decreases during storage and application. Therefore, innovation is needed regarding the formulation of biological fertilizer carriers that have the potential to maintain microbial viability and effectivity during storage. The comprehensive study was carried out using Systematic Literature Review (SLR) method by the search engine to evaluate and assess the current status of solid carrier formulation to improve the viability and effectiveness of biofertilizers inoculants. The results of a systematic review of scientific literature were obtained from as many as 149 articles from ScienceDirect and Scopus, and a total of 10 articles were chosen for further review. Several carrier materials have been reported can increase the viability and effectiveness of N-fixing inoculant. Each carrier material provides various benefits, such as increased microbial shelf life, microbial activity, and plant growth. Some carrier materials have the potential for further development in Indonesia.

Effect of different finishing and polishing procedures on surface roughness and microbial adhesion on highly-filled composites for injectable mold technique.

To evaluate the effect of different finishing and polishing procedures on surface roughness and microbial adhesion and viability of Streptococcus mutans on novel highly-filled composites for injectable mold technique. One hundred sixty specimens were divided into four material groups: FSF (Filtek Supreme Flowable Restorative), TE (Tetric EvoFlow), GUI (G-aenial Universal Injectable) and GUF (G-aenial Universal Flo). Within each group, specimens were split regarding finishing and polishing (F/P) procedures into: SLD (Sof-Lex Discs), SLS (Sof-Lex Spirals), OG (OneGloss) and PG (PoGo). Surface roughness was analyzed using profilometer (Ra and Rz) and scanning electron microscopy (SEM) and Strep. mutans biofilm formation was analyzed using colony forming unit (CFU) and cell viability assay. Two-way analysis of variance (ANOVA) followed by Tukey's post hoc test were used for comparison among groups, Pearson's coefficient was applied for the correlation between Ra and CFU/ml and all data were presented as mean ± SD. Both materials and F/P procedures affect Ra, Rz and Strep. mutans CFU/ml values (p ≤ 0.05). Considering the Ra and Rz, GUI and GUF revealed lower values, compared to FSF and TE and SLD and SLS revealed lower values, compared to OG and PG. Considering the Strep. mutans CFU/ml and viability, GUI and TE presented lower values, compared to GUF and FSF and SLD and SLS presented lower values, compared to OG and PG. Moderate positive correlation was found between Ra and CFU/ml (r = 0.552). The smoothest surfaces possess GUI and GUF, among materials and SLD and SLS, among F/P procedures. GUI adhered the lowest amount of Strep. mutans, due to the smoothest surfaces. FSF and GUF revealed the highest amount of Strep. mutans, due to bis-GMA, bis-MEPP and TEGDMA in their composition. The findings of the present study may be beneficial for the proper selection of highly-filled composites and an adequate finishing and polishing procedure when performing the injectable mold composite resin veneer technique.

Process Development for the Spray-Drying of Probiotic Bacteria and Evaluation of the Product Quality

Probiotics and prebiotics are of great interest to the food and pharmaceutical industries due to their health benefits. Probiotics are live bacteria that can confer beneficial effects on human and animal wellbeing, while prebiotics are types of nutrients that feed the beneficial gut bacteria. Powder probiotics have gained popularity due to the ease and practicality of their ingestion and incorporation into the diet as a food supplement. However, the drying process interferes with cell viability since high temperatures inactivate probiotic bacteria. In this context, this study aimed to present all the steps involved in the production and physicochemical characterization of a spray-dried probiotic and evaluate the influence of the protectants (simulated skim milk and inulin:maltodextrin association) and drying temperatures in increasing the powder yield and cell viability. The results showed that the simulated skim milk promoted higher probiotic viability at 80 °C. With this protectant, the probiotic viability, moisture content, and water activity (Aw) reduce as long as the inlet temperature increases. The probiotics' viability decreases conversely with the drying temperature.At temperatures close to 120 °C, the dried probiotic showed viability around 90%, a moisture content of 4.6% w/w, and an Aw of 0.26; values adequate to guarantee product stability. In this context, spray-drying temperatures above 120 °C are required to ensure the microbial cells' viability and shelf-life in the powdered preparation and survival during food processing and storage.

The Blood Microbiome and Health: Current Evidence, Controversies, and Challenges.

Blood is conventionally thought to be sterile. However, emerging evidence on the blood microbiome has started to challenge this notion. Recent reports have revealed the presence of genetic materials of microbes or pathogens in the blood circulation, leading to the conceptualization of a blood microbiome that is vital for physical wellbeing. Dysbiosis of the blood microbial profile has been implicated in a wide range of health conditions. Our review aims to consolidate recent findings about the blood microbiome in human health and to highlight the existing controversies, prospects, and challenges around this topic. Current evidence does not seem to support the presence of a core healthy blood microbiome. Common microbial taxa have been identified in some diseases, for instance, Legionella and Devosia in kidney impairment, Bacteroides in cirrhosis, Escherichia/Shigella and Staphylococcus in inflammatory diseases, and Janthinobacterium in mood disorders. While the presence of culturable blood microbes remains debatable, their genetic materials in the blood could potentially be exploited to improve precision medicine for cancers, pregnancy-related complications, and asthma by augmenting patient stratification. Key controversies in blood microbiome research are the susceptibility of low-biomass samples to exogenous contamination and undetermined microbial viability from NGS-based microbial profiling, however, ongoing initiatives are attempting to mitigate these issues. We also envisage future blood microbiome research to adopt more robust and standardized approaches, to delve into the origins of these multibiome genetic materials and to focus on host-microbe interactions through the elaboration of causative and mechanistic relationships with the aid of more accurate and powerful analytical tools.

Effect of Axial Ligand Length on Biological and Anticancer Properties of Axially Disubstituted Silicon Phthalocyanines.

In this study, three new axially disubstituted silicon phthalocyanines (SiPc1-3) and their quaternized phthalocyanine derivatives (QSiPc1-3) were prepared and characterized. The biological properties (antioxidant, antimicrobial, antibiofilm, and microbial cell viability activities) of the water-soluble silicon phthalocyanines were examined, as well. A 1 % DMSO diluted with pure water was used as a solvent in biological activity studies. All the compounds exhibited high antioxidant activity. They displayed efficient antimicrobial and antimicrobial photodynamic therapeutic properties against various microorganisms, especially Gram (+) bacteria. Additionally, they demonstrated high antibiofilm activities against S. aureus and P. aeruginosa. In addition, 100 % bacterial reduction was obtained for all the studied phthalocyanines against E. coli viable cells. Besides, the DNA cleavage and binding features of compounds (QSiPc1-3) were studied using pBR322 DNA and CT-DNA, respectively. Furthermore, the human topoisomerase I enzyme inhibition activities of compounds QSiPc1-3 were studied. Anticancer properties of the water-soluble compounds were investigated using cell proliferation MTT assay. They exhibited anticarcinogenic activity against the human colon cancer cell line (DLD-1). Compounds QSiPc1 and QSiPc3 displayed a high anticarcinogenic effect on the DLD-1 cell line. The obtained results indicated that all the studied compounds may be effective biological agents and anticancer drugs after further investigations.

Effect of Process Parameters, Protectants and Carrier Materials on the Survival of Yeast Cells during Fluidized Bed Granulation for Tableting.

The administration of living microorganisms is of special interest, with regard to probiotic microorganisms providing health benefits to the patient. Effective dosage forms require the preservation of microbial viability until administration. Storage stability can be improved by drying, and the tablet is an especially attractive final solid dosage form due to its ease of administration and its good patient compliance. In this study, drying of the yeast Saccharomyces cerevisiae via fluidized bed spray granulation is investigated, as the probiotic Saccharomyces boulardii is a variety of it. Fluidized bed granulation enables faster drying than lyophilization on the one hand and lower temperatures than spray drying on the other hand, which are the two predominantly used techniques for life-sustaining drying of microorganisms. Yeast cell suspensions enriched with protective additives were sprayed onto the carrier particles of common tableting excipients, namely, dicalcium phosphate (DCP), lactose (LAC) and microcrystalline cellulose (MCC). Different protectants, such as mono-, di-, oligo- and polysaccharides, but also skimmed milk powder and one alditol, were tested; as they themselves, or chemically similar molecules, are known from other drying technologies to stabilize biological structures such as cell membranes, and thus, improve survival during dehydration. With the combined use of trehalose and skimmed milk powder, survival rates were 300 times higher than without the use of protective additives. In addition to these formulation aspects, the influence of process parameters such as inlet temperature and spray rate were considered. The granulated products were characterized regarding their particle size distribution, moisture content and the viability of the yeast cells. It has been shown that thermal stress on the microorganisms is especially critical, which can be reduced, for example, by reducing the inlet temperature or increasing the spray rate; however, formulation parameters such as cell concentration also influenced survival. The results were used to specify the influencing factors on the survival of microorganisms during fluidized bed granulation and to derive their linkages. Granules based on the three different carrier materials were tableted and the survival of the microorganisms was evaluated and linked to the tablet tensile strength achieved. Using LAC enabled the highest survival of the microorganisms throughout the considered process chain.

Nutritional, antioxidant, and antimicrobial assessment of carrot powder and its application as a functional ingredient in probiotic soft cheese

Carrots (the main source of carotenoids) have multiple nutritional and health benefits. The objectives of this study were to evaluate the compositional, antioxidant, and antimicrobial properties of carrot powder and to examine its effect on the sensory characteristics, chemical properties, and microbial viability of probiotic soft cheese at a rate of 0.2, 0.4, and 0.6%. The carrot was turned into powder before being analyzed and incorporated as an ingredient in making probiotic soft cheese. Probiotic soft cheese was made from buffalo milk. The buffalo milk (∼6.9% fat, 4.4% protein, 9.2% milk solids not fat, and 0.7% ash) was pasteurized at 75 ± 1°C for 5 min and cooled to 40-42°C. The milk was then divided into 4 aliquots. Sodium chloride (local market, Assiut, Egypt) was added at a ratio of 5% followed by starter cultures. The carrot powder (4.5% moisture, 4.8% ash, 2.7% fat, 8.2% protein, 11.9% fibers, and 72.3% carbohydrate) was added at a rate of 0.2, 0.4, and 0.6%, followed by addition of 0.02 g/kg rennet. The cheese was cut again into cubes, pickled in jars filled with whey, and stored for 28 d at 6 ± 1°C. The results of this study illustrated the nutritional and antioxidant properties of carrot powder. Incorporation of carrot powder in probiotic soft cheese affected the moisture and salt content at 0 d. The total bacteria count decreased from 7.5 to 7.3 log cfu/g in the cheese when carrot powder was used at a rate of 0.6%. The reduction of total bacteria count was noticed during the 28 d of storage by adding carrot powder. Furthermore, lactic acid bacteria and Bifidobacterium longum counts elevated with adding carrot powder during the 28 d of storage.

The Activity of Calcium Glycerophosphate and Fluoride against Cariogenic Biofilms of Streptococcus mutans and Candida albicans Formed In Vitro.

This study evaluated the effects of calcium glycerophosphate (CaGP), with or without fluoride (F), on dual-species biofilms of Streptococcus mutans and Candida albicans. The biofilms were treated three times with 0.125, 0.25, and 0.5% CaGP solutions, with or without 500 ppm F (NaF). Additionally, 500 and 1100 ppm F-solutions and artificial saliva served as controls. After the final treatment, the microbial viability and biofilm structure, metabolic activity, total biomass production, and the composition of the extracellular matrix composition were analyzed. Regardless of the presence of F, 0.25 and 0.5% CaGP promoted a higher biomass production and metabolic activity increase than the controls (p < 0.05). F-free CaGP solutions reduced bacterial cell population significantly more than the 500 ppm F group or the negative control (p < 0.05). All the groups reduced the proteins, and 0.5% CaGP combined with F led to the highest reduction in the carbohydrate and nucleic acids content of the extracellular matrix (p < 0.05). It can be concluded that CaGP alone affected the number of bacterial cells and, when combined with F, reduced its production of biomass, metabolic activity, and the expression of the extracellular matrix components.

Extracellular biomineralization of uranium and its toxicity alleviation to Bacillus thuringiensis X-27

Uranium biomineralization can slow uranium migration in the environment and thus prevent it from further contaminating the surroundings. Investigations into the uranium species, pH, inorganic phosphate (Pi) concentration, and microbial viability during biomineralization by microorganisms are crucial for understanding the mineralization mechanism. In this study, Bacillus thuringiensis X-27 was isolated from soil contaminated with uranium and was used to investigate the formation process of uranium biominerals induced by X-27. The results showed that as biomineralization proceeded, amorphous uranium-containing deposits were generated and transformed into crystalline minerals outside cells, increasing the overall concentration of uramphite. This is a cumulative rather than abrupt process. Notably, B. thuringiensis X-27 precipitated uranium outside the cell surface within 0.5 h, while the release of Pi into the extracellular environment and the change of pH to alkalescence further promoted the formation of uramphite. In addition, cell viability determination showed that the U(VI) biomineralization induced by B. thuringiensis X-27 was instrumental in alleviating the toxicity of U(VI) to cells. This work offers insight into the mechanism of U(VI) phosphate biomineralization and is a reference for bioremediation-related studies.

Effect of Processing Methods of Human Saliva on the Proteomic Profile and Protein-Mediated Biological Processes.

The use of saliva as a protein source prior to microbiological and biological assays requires previous processing. However, the effect of these processing methods on the proteomic profile of saliva has not been tested. Stimulated human saliva was collected from eight healthy volunteers. Non-processed saliva was compared with 0.22 μm filtered, 0.45 μm filtered, and pasteurized saliva, by liquid chromatography-mass spectrometry. Data are available via ProteomeXchange with identifier PXD039248. The effect of processed saliva on microbial adhesion was tested using bacterial and fungus species and in biological cell behavior using HaCaT immortalized human keratinocytes. Two hundred and seventy-eight proteins were identified in non-processed saliva, of which 54 proteins (≈19%) were exclusive. Saliva processing reduced identified proteins to 222 (≈80%) for the 0.22 μm group, 219 (≈79%) for the 0.45 μm group, and 201 (≈72%) for the pasteurized saliva, compared to non-processed saliva. The proteomic profile showed similar molecular functions and biological processes. The different saliva processing methods did not alter microbial adhesion (ANOVA, p > 0.05). Interestingly, pasteurized saliva reduced keratinocyte cell viability. Saliva processing methods tested reduced the proteomic profile diversity of saliva but maintained similar molecular functions and biological processes, not interfering with microbial adhesion and cell viability, except for pasteurization, which reduced cell viability.

Milk fermentation with prebiotic flour of Vasconcellea quercifolia A.St.-Hil.

Non-conventional food plants have bioactive compounds and a high nutritional value. Among these, Vasconcellea quercifolia has nutritional benefits, but it is also easy to cultivate and has a low production cost. In this study, the flour from the unripe fruit of V. quercifolia was evaluated in terms of its potential as a prebiotic for the probiotic bacteria Lactobacillus acidophilus and Bifidobacterium lactis. To do so, fermented milk samples were prepared with 2%, 3%, and 6% of flour and 8.25 log CFU/mL of each microorganism. Samples were analyzed in terms of the number of viable cells of L. acidophilus and B. lactis, as well as pH level, total solids, titratable acidity, and texture in the course of 21days of storage at 4ºC. The obtained microbial viability revealed the in vitro symbiotic effect of flour from V. quercifolia on the probiotic strains of L. acidophilus and B. lactis, which reached 10.20 and 11.19 log CFU/mL, respectively, after 21days of storage, showing a significant difference in cell growth of 1.7 and 2.5 log CFU/mL compared with the control. The pH level decreased from 4.8 to 4.5 after storage time, so it did not alter the conditions for the growth of bacteria. The physical and chemical parameters analyzed did not reveal significant differences (p > 0.05), which indicates product stability. Therefore, flour from the unripe fruit of V. quercifolia has a prebiotic property and can be used as a nutritional supplement for L. acidophilus and B. lactis.

Bioaerosols in an industrial park and the adjacent houses: Dispersal between indoor/outdoor, the impact of air purifier, and health risk reduction

Inhaling airborne pathogens may cause severe epidemics showing huge threats to indoor dwellings residents. The ventilation, environmental parameters, and human activities would affect the abundance and pathogenicity of bioaerosols in indoor. However, people know little about the indoor airborne microbes especially pathogens near the industrial park polluted with organics and heavy metals. Herein, the indoor bioaerosols’ community composition, source and influencing factors near an electronic waste (e-waste) industrial park were investigated. Results showed that the average bioaerosol level in the morning was lower than evening. Bioaerosol concentration and activity in indoor (1936 CFU/m3 and 7.62 × 105 ng/m3 sodium fluorescein in average) were lower than the industrial park (4043 CFU/m3 and 7.77 × 105 ng/m3 sodium fluorescein), and higher microbial viability may be caused by other pollutants generated during e-waste dismantling process. Fluorescent biological aerosol particles occupied 17.6%−23.7% of total particles, indicating that most particles were non-biological. Bacterial communities were richer and more diverse than fungi. Furthermore, Bacillus and Cladosporium were the dominant indoor pathogens, and pathogenic fungi were more influenced by environmental factors than bacteria. SourceTracker analysis indicates that outdoor was the main source of indoor bioaerosols. The hazard quotient (<1) of airborne microbes through inhalation was negligible, but long-term exposure to pathogens could be harmful. Air purifiers could effectively remove the airborne fungi and spheroid bacteria than cylindrical bacteria, but open doors and windows would reduce the purification efficiency. This study is great important for risk assessments and control of indoor bioaerosols near industrial park.

Heterotrophic anodic denitrification coupled with cathodic metals recovery from on-site smelting wastewater with a bioelectrochemical system inoculated with mixed Castellaniella species

Although Castellaniella species are crucial for denitrification, there is no report on their capacity to carry out denitrification and anode respiration simultaneously in a bioelectrochemical system (BES). Herein, the ability of a mixed inoculum of electricigenic Castellaniella species to perform simultaneous denitrification and anode respiration coupled with cathodic metals recovery was investigated in a BES. Results showed that 500 mg/L NO3−-N significantly decreased power generation, whereas 100 and 250 mg/L NO3−-N had a lesser impact. The single-chamber MFCs (SCMFCs) fed with 100 and 250 mg/L NO3−-N concentrations achieved a removal efficiency higher than 90% in all cycles. In contrast, the removal efficiency in the SCMFCs declined dramatically at 500 mg/L NO3−-N, which might be attributable to decreased microbial viability as revealed by SEM and CLSM. EPS protein content and enzymatic activities of the biofilms decreased significantly at this concentration. Cyclic voltammetry results revealed that the 500 mg/L NO3−-N concentration decreased the redox activities of anodic biofilms, while electrochemical impedance spectroscopy showed that the internal resistance of the SCMFCs at this concentration increased significantly. In addition, BES inoculated with the Castellaniella species was able to simultaneously perform heterotrophic anodic denitrification and cathodic metals recovery from real wastewater. The BES attained Cu2+, Hg2+, Pb2+, and Zn2+ removal efficiencies of 99.86 ± 0.10%, 99.98 ± 0.014%, 99.98 ± 0.01%, and 99.17 ± 0.30%, respectively, from the real wastewater. Cu2+ was bio-electrochemically reduced to Cu0 and Cu2O, whereas Hg0 and HgO constituted the Hg species recovered via bioelectrochemical reduction and chemical deposition, respectively. Furthermore, Pb2+ and Zn2+ were bio-electrochemically reduced to Pb0 and Zn0, respectively. Over 89% of NO3−-N was removed from the BES anolyte during the recovery of the metals. This research reveals promising denitrifying exoelectrogens for enhanced power generation, NO3−-N removal, and heavy metals recovery in BES.

Aroma profiles of sweet cherry juice fermented by different lactic acid bacteria determined through integrated analysis of electronic nose and gas chromatography-ion mobility spectrometry.

Sweet cherries are popular among consumers, with a recent explosion in sweet cherry production in China. However, the fragility of these fruits poses a challenge for expanding production and transport. With the aim of expanding the product categories of sweet cherries that can bypass these challenges, in this study, we prepared sweet cherry juice fermented by three different lactic acid bacteria (LAB; Lactobacillus acidophilus, Lactobacillus plantarum, and Lactobacillus rhamnosus GG), and evaluated the growth, physiochemical, and aroma characteristics. All three strains exhibited excellent growth potential in the sweet cherry juice; however, Lactobacillus acidophilus and Lactobacillus plantarum demonstrated more robust acid production capacity and higher microbial viability than Lactobacillus rhamnosus GG. Lactic acid was the primary fermentation product, and malic acid was significantly metabolized by LAB, indicating a transition in microbial metabolism from using carbohydrates to organic acids. The aroma profile was identified through integrated analysis of electronic nose (E-nose) and headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS) data. A total of 50 volatile compounds characterized the aromatic profiles of the fermented juices by HS-GC-IMS. The flavor of sweet cherry juice changed after LAB fermentation and the fruity odor decreased overall. Lactobacillus acidophilus and Lactobacillus plantarum significantly increased 2-heptanone, ethyl acetate, and acetone contents, bringing about a creamy and rummy-like favor, whereas Lactobacillus rhamnosus GG significantly increased 2-heptanone, 3-hydroxybutan-2-one, and 2-pentanone contents, generating cheesy and buttery-like odors. Principal component analysis of GC-IMS data and linear discriminant analysis of E-nose results could effectively differentiate non-fermented sweet cherry juice and the sweet cherry juice separately inoculated with different LAB strains. Furthermore, there was a high correlation between the E-nose and GC-IMS results, providing a theoretical basis to identify different sweet cherry juice formulations and appropriate starter culture selection for fermentation. This study enables more extensive utilization of sweet cherry in the food industry and helps to improve the flavor of sweet cherry products.

Impact of Potentilla anserine polysaccharide on storage properties of probiotic yak yoghurt

The influence of Potentilla anserine polysaccharide (PAP) on microbial viability, physicochemical properties, sensory characteristics and antioxidant activities in probiotic yak yoghurts during 21 days of storage were evaluated. PAP significantly increased the number of Lactobacillus plantarum DNZ-4, Streptococcus thermophilus and Lactobacillus bulgaricus, which were higher than 7 log cfu mL−1 during storage. Addition of PAP delayed the post acidification process in probiotic yak yoghurt during storage, and improved water-holding capacity and rheological properties. Especially, gel structure of 0.1% PAP probiotic yak yoghurt was more fine and smooth, and sensory acceptability was the best. Furthermore, compared with the control, antioxidant activities in PAP probiotic yak yoghurts were significantly improved (p <0.05) and hydroxyl radical scavenging rates of 0.1% PAP probiotic yak yoghurt still reached 57 ± 1.35% on day 21 of storage. Therefore, PAP could improve probiotic yak yoghurt storage properties and enhance functional added value of the product.

New AB3-type porphyrins with piperidine and morpholine motifs; synthesis and photo-physicochemical and biological properties.

In this study, new unsymmetrical meso-tetraaryl AB3-type porphyrins 1 and 2 were successfully synthesized by the reaction of p-bromobenzaldehyde and p-hydroxybenzaldehyde with pyrrole in propionic acid. AB3-type porphyrin building blocks with hydroxyl functionality (1 and 2) were further used to generate both covalently linked metal free and Zn(II) porphyrins 3-6 having piperidine and morpholine heterocyclic units. These novel compounds were characterized by using 1H NMR, 13C NMR, FT-IR and MALDI-TOF spectrophotometry. The photophysical and photochemical properties of compounds 1-6 were investigated by employing UV-vis absorption and fluorescence emission spectroscopy in tetrahydrofuran (THF). From the view of biological properties, the antioxidant capacities of porphyrins were determined by using DPPH radical scavenging activity and 2 was determined as the most potent porphyrin analog with a value of 98.42% at 200 mg L-1. All the targeted compounds displayed significant DNA nuclease activity. In addition, the antimicrobial potential of compounds 1-6 was also investigated by a micro-dilution process and 2 was found to be the most effective candidate against the tested microbial strains. The newly synthesized porphyrins also showed 100% microbial cell viability inhibition against E. coli at all examined concentrations. In terms of biofilm inhibition activity, the best results for the maximum photodynamic antimicrobial biofilm inhibition of S. aureus and P. aeruginosa were obtained by compound 2 with the values of 99.75% and 93.39%, respectively.

Effect of substrate type and incubation time on the microbial viability of instant starter for premium tempeh

&lt;abstract&gt; &lt;p&gt;Premium tempeh starter is a tempeh starter containing a mixed inoculum of &lt;italic&gt;Rhizopus oligosporus&lt;/italic&gt; and &lt;italic&gt;Saccharomyces cerevisiae&lt;/italic&gt;. Previously, premium tempeh starter was made in the form of liquid culture. This study aims to produce premium tempeh starter in powder form with the best type of substrate and incubation time so that it can be used practically. In this study, the effect of substrate type and incubation time on microbial viability of instant premium tempeh starter was studied. The study was arranged in a Completely Randomized Block Design with two factors and three replications. The first factor was the type of substrate: tapioca flour and rice flour, while the second factor was the incubation time at room temperature: 0, 24, 48, 72, 96 and 120 hours. The instant premium tempeh starter was analyzed for pH value, water content, number of fungi, yeast and bacteria. The microbial viability of tempeh starter was indicated by the growth of fungi, yeast and bacteria during incubation. The data obtained were analyzed by analysis of variance and further tested with the Honest Significant Difference (HSD) test at a 5% significance level. The results showed that rice flour and incubation time of 96 hours produced the best premium tempeh instant starter with the number of fungi of 9.02 Log CFU/g, 9.17 Log CFU/g yeast, 7.81 Log CFU/g bacteria, pH 4.2 and 7.75% water content. Tempeh made using the best premium tempeh instant starter has a chemical composition in accordance with the tempeh product standard (SNI 3144:2015).&lt;/p&gt; &lt;/abstract&gt;