Higher Viable Counts Research Articles

A comprehensive study on the autochthonous microbiota, volatilome, physico-chemical, and morpho-textural features of Montenegrin Njeguški cheese

The present study aims to deepen the knowledge of the microbiota, gross composition, physico-chemical and morpho-textural features, biogenic amines content and volatilome of Njeguški cheese, one of the most popular indigenous cheeses produced in Montenegro. Cheese samples were collected in duplicate from three different batches produced by three Montenegrin artisan producers. For the first time, the microbiota of Njeguški cheese was investigated using both culture-dependent techniques and metagenomic analysis. Coagulase positive staphylococci viable counts were below the detection limit of the analysis (<1 log cfu g−1). Salmonella spp., Listeria monocytogenes and staphylococcal enterotoxins were absent. However, relatively high viable counts of Enterobacteriaceae, Escherichia coli, Pseudomonadaceae and eumycetes were detected. Metataxonomic analysis revealed a core microbiome composed of Lactococcus lactis, Streptococcus thermophilus, Debaryomyces hansenii, and Kluyveromyces marxianus. Furthermore, the detection of opportunistic pathogenic yeasts such as Magnusiomyces capitatus and Wickerhamiella pararugosa, along with the variable content of biogenic amines, suggests the need for increased attention to hygienic conditions during Njeguški cheese production. Significant variability was observed in humidity (ranging from 38.37 to 45.58 %), salt content (ranging from 0.70 to 1.78 %), proteins content (ranging from 21.42 to 25.08 %), ash content (ranging from 2.97 to 4.05 %), hardness, springiness, and color among samples from different producers. Gas chromatography-mass spectrometry analysis showed a well-defined and complex volatilome profile of the Njeguški cheese, with alcohols (ethanol, isoamyl alcohol, phenetyl alcol), esters and acetates (ethyl acetate, ethyl butanoate, isoamyl acetate), ketones (acetoin, 2-butanone), and acids (acetic, butanoic, hexanoic acids) being the main chemical groups involved in aroma formation. This research will provide new insights into the still poorly explored identity of Njeguški cheese, thus serving as a first baseline for future studies aimed at protecting its tradition.

Safe and Healthy Food Preservation: Efficacy of Guava Leaves and Lemon Juice Extract on Fruits and Vegetables

Background: Fruits and vegetables are naturally perishable and have a relatively limited shelf life. This study was designed to prolong the shelf life and remain nutritional value of various fruits and vegetables by using guava leaves extract and lemon juice extract (natural preservatives). Methods: Fruits and vegetables samples (amla, banana, grapes, bean, eggplant and tomato) were treated with three types of natural preservatives: guava leaves and lemon juice extract (GLE) 0.5% (boiled), lemon extract (LE) 15%, GLE 40% + LE 15%. Results: The study revealed that the moisture content varied from 18.03% to 95.41%. During the 10 days of experiment, samples treated with 0.5% GLE (boiled) preservatives exhibited better result than other two types of preservatives regarding the moisture content. Titratable acidity content varied from 0.05% to 2.25%. The pH value varied in the range of 2.47-6.01. The percentage of weight loss value ranged from 3.67 to 85.71. During the experiment period, weight loss was minimum almost in all samples treated with GLE 40%+LE 15% preservative. The vitamin C content in fruits and vegetables ranged from 1.60 mg/100mL to 68.46mg/100mL. The highest viable count was found in banana (46×104 CFU/ml) and the lowest was in Bean (9×104 CFU/ml). Conclusion: Among three types of preservatives, samples treated with 0.5% GLE (boiled) showed better result and minimum microbial growth.

Exploiting tropical fruit processing coproducts as circular resources to promote the growth and maintain the culturability and functionality of probiotic lactobacilli

This study evaluated the use of acerola (Malpighia glabra L., CACE), cashew (Anacardium occidentale L., CCAS), and guava (Psidium guayaba L., CGUA) fruit processing coproducts as substrates to promote the growth, metabolite production, and maintenance of the viability/metabolic activity of the probiotics Lactobacillus acidophilus LA-05 and Lacticaseibacillus paracasei L-10 during cultivation, freeze-drying, storage, and exposure to simulated gastrointestinal digestion. Probiotic lactobacilli presented high viable counts (≥8.8 log colony-forming units (CFU)/mL) and a short lag phase during 24 h of cultivation in CACE, CCAS, and CGUA. Cultivation of probiotic lactobacilli in fruit coproducts promoted sugar consumption, medium acidification, and production of organic acids over time, besides increasing the of several phenolic compounds and antioxidant activity. Probiotic lactobacilli cultivated in fruit coproducts had increased survival percentages after freeze-drying and during 120 days of refrigerated storage. Moreover, probiotic lactobacilli cultivated and freeze-dried in fruit coproducts had larger subpopulations of live and metabolically active cells when exposed to simulated gastrointestinal digestion. The results showed that fruit coproducts not only improved the growth and helped to maintain the viability and metabolic activity of probiotic strains but also enriched the final fermented products with bioactive compounds, being an innovative circular strategy for producing high-quality probiotic cultures.

Cereus jamacaru DC. (mandacaru) fruit as a source of lactic acid bacteria with in vitro probiotic-related characteristics and its protective effects on Pediococcus pentosaceus during lyophilization and refrigeration storage

This study isolated and identified autochthonous lactic acid bacteria (LAB) from mandacaru fruit and evaluated their potential probiotic and technological aptitudes in vitro, as well as the protective effects of freeze-dried mandacaru fruit on the most promising LAB isolate during lyophilization and refrigeration storage. Initially, 212 colonies were isolated from mandacaru fruit, and 34 were preliminarily identified as LAB. Thirteen isolates identified by 16S-rRNA sequencing as Pediococcus pentosaceus were negative for DNase, gelatinase, hemolytic, and biogenic amine production. The selected isolates showed proteolytic activity, diacetyl and exopolysaccharide production, and good tolerance to different NaCl concentrations while having low cellular hydrophobicity and antagonistic activity against pathogens. The survival of isolates sharply decreased after 3 h of exposure to pH 2 and had a good tolerance to 1 % bile salt. A principal component analysis selected P. pentosaceus 57 as the most promising isolate based on the examined technological and probiotic-related physiological properties. This isolate was lyophilized with mandacaru fruit and stored under refrigeration for 90 days. P. pentosaceus 57 lyophilized with mandacaru fruit had high viable cell counts (9.69 ± 0.03 log CFU/mL) and >50 % of physiologically active cells at 90 days of refrigeration storage. The results indicate that mandacaru fruit is a source of P. pentosaceus with aptitudes to be explored as potential probiotic and technological characteristics of interest for the food industry, besides being a good candidate for use in lyophilization processes and refrigeration storage of LAB due to its cryoprotective effects.

Development of a probiotic low-fat set yogurt containing concentrated sweet pepper extract.

Yogurt contains various health-promoting components such as beneficial bacteria and bioactive peptides. However, plain yogurt is regarded as a poor source of phenolic compounds, vitamin C, and other substances that give a high antioxidant property to the product. Since the objective of this study was to evaluate the impact of the addition of different concentrated sweet pepper extracts (CSPE) to the yogurt milk formulation on some quality parameters of the probiotic set yogurt during 21 days of cold storage. For the production of probiotic yogurt samples, Lactobacillus acidophilus LA-5 was used as probiotic bacteria. The functional set yogurts containing 5% of yellow, orange, or red CSPE were prepared and compared with probiotic control yogurt (without CSPE). With incorporation of CSPE, a functional yogurt with high viable cell counts of probiotics (>108 cfu/g), appropriate acceptability (acceptance scores more than 7, i.e., good acceptability), and textural quality produced. Fortified CSPE yogurt displayed large flakes with irregular surface and more compact texture as compared to the control sample. Based on the results of the study, the yogurt sample having orange CSPE was selected as the best functional product. After 21 days of storage, orange CSPE had the highest hardness (173.33 mg), consistency (1183.33 mg/s), and probiotic counts (8.3 log cfu/g) than other yogurt samples.

The influence of nutrients on biofilm formation of an ST87 strain of Listeria monocytogenes

Biofilm development by pathogenic organisms plays a pivotal role in certain foodborne illnesses. Listeria monocytogenes, specifically the sequence type 87 (ST87), has been widely identified in China. This study aimed to monitor the dynamic process of biofilm formation by a food-isolated L. monocytogenes ST87 strain under diverse nutritional conditions. Results showed that this strain can consistently exhibit high viable cell counts in both nutrient-rich and nutrient-limited conditions. By utilizing cell counting, we discovered the ability of L. monocytogenes ST87 to form biofilms in various nutritional environments, including beef juice and vegetable juice, maintaining levels above 2 Log10 CFU/cm2. Notably, biofilm formation was expedited under nutrient-limited conditions, with cell counts under nutrient-limited vegetable juice presenting significantly higher than that under the nutrient-rich one. The analysis of the composition of extracellular polymeric substances (EPS) showed a consistent pattern between viable cell count and extracellular protein variation within the biofilms. Moreover, an evaluation of nutritional components (protein, fat, total sugar, ash, and pH) in the culture medium unveiled a positive correlation between extracellular substances and pH, but a negative correlation was identified with other nutritional components.

An In Vitro Study of the Impacts of Sweet Potato Chips with Potentially Probiotic Levilactobacillus brevis and Lactiplantibacillus plantarum on Human Intestinal Microbiota : Impacts of potato chips with probiotics on intestinal microbiota.

This study formulated sweet potato chips with powdered potentially probiotic Levilactobacillus brevis (SPLB) and Lactiplantibacillus plantarum (SPLP) and evaluated their impacts on human intestinal microbiota during 48h of in vitro colonic fermentation. L. brevis and L. plantarum kept high viable cell counts (> 6 log CFU/g) on sweet potato chips after freeze-drying and during 60days of storage. SPLB and SPLP had satisfactory quality parameters during 60days of storage. SPLB and SPLP increased the relative abundance of Lactobacillus ssp./Enterococcus spp. (3.84-10.22%) and Bifidobacterium spp. (3.25-12.45%) and decreased the relative abundance of Bacteroides spp./Prevotella spp. (8.56-2.16%), Clostridium histolyticum (8.23-2.33%), and Eubacterium rectale/Clostridium coccoides (8.07-1.33%) during 48h of in vitro colonic fermentation. SPLB and SPLP achieved high positive prebiotic indexes (> 8.24), decreased pH values and sugar contents, and increased lactic acid and short-chain fatty acid production, proving selective stimulatory effects on beneficial bacterial groups forming the intestinal microbiota. The results showed that SPLB and SPLP have good stability and high viable cell counts of L. brevis and L. plantarum when stored under room temperature and caused positive impacts on human intestinal microbiota, making them potentially probiotic non-dairy snack options.

Purification of phage for therapeutic applications using high throughput anion exchange membrane chromatography

As cases of multidrug resistant bacterial infections increase, scientists and clinicians around the world are increasingly turning to bacteriophages as alternatives to antibiotics. Even though our understanding of phage has increased significantly since the early days of its discovery, over a century ago, the currently used tools and technologies for phage purification for therapeutic applications are severely limited. Bacteriophages are produced by bacterial cultures, and impurities such as endotoxins must therefore be removed before clinical use. We present an anion exchange bind-and-elute membrane chromatographic method for purifying T7 bacteriophage from Escherichia coli culture supernatant that removes undesirable impurities, while ensuring a high viable phage count in the purified product. Our method does not involve the use of chemicals such as organic solvents and caesium chloride that could typically leave residual toxicity in the final product. It also does not require expensive equipment, such as an ultracentrifuge. Using our method, that is based on an in-house designed membrane module, 65% of viable T7 phage was recovered, and up to 94% endotoxins could be removed. The method, which took approximately 15 min, is rapid and scalable, and produces quite pure bacteriophage samples in a single step. It therefore potentially represents a major improvement over the status quo, and shows the way ahead for streamlining phage manufacturing for therapeutic use.

Revealing the Potential Impacts of Nutraceuticals Formulated with Freeze-Dried Jabuticaba Peel and Limosilactobacillus fermentum Strains Candidates for Probiotic Use on Human Intestinal Microbiota.

This study evaluated the impacts of novel nutraceuticals formulated with freeze-dried jabuticaba peel (FJP) and three potentially probiotic Limosilactobacillus fermentum strains on the abundance of bacterial groups forming the human intestinal microbiota, metabolite production, and antioxidant capacity during in vitro colonic fermentation. The nutraceuticals had high viable counts of L. fermentum after freeze-drying (≥ 9.57 ± 0.09 log CFU/g). The nutraceuticals increased the abundance of Lactobacillus ssp./Enterococcus spp. (2.46-3.94%), Bifidobacterium spp. (2.28-3.02%), and Ruminococcus albus/R. flavefaciens (0.63-4.03%), while decreasing the abundance of Bacteroides spp./Prevotella spp. (3.91-2.02%), Clostridium histolyticum (1.69-0.40%), and Eubacterium rectale/C. coccoides (3.32-1.08%), which were linked to positive prebiotic indices (> 1.75). The nutraceuticals reduced the pH and increased the sugar consumption, short-chain fatty acid production, phenolic acid content, and antioxidant capacity, besides altering the metabolic profile during colonic fermentation. The combination of FJP and probiotic L. fermentum is a promising strategy to produce nutraceuticals targeting intestinal microbiota.

Enhancement of gum Arabic/casein microencapsulation on the survival of Lactiplantibacillus plantarum in the stimulated gastrointestinal conditions

Probiotic products that contain lactobacilli have long histories of safe use as Lactobacillus strains have many physiological functions in the gastrointestinal tract (GIT). However, the viability of probiotics can be affected by food processing and the adverse environment. This study investigated the O/W (Oil-in-water emulsions) emulsions formed by coagulation of casein/GA (Gum Arabic) complexes for Lactiplantibacillus plantarum microencapsulation, and the stability of the strains during gastrointestinal environment were also determined. The results showed that the particle size of the emulsion decreased from 9.72 μm to 5.48 μm when the GA concentration increased from 0 to 2 (w/v), and the emulsion particles were found to be more uniform as observed by CLSM (Confocal Laser Scanning Microscope). The surface of this microencapsulated casein/GA composite forms smooth, dense agglomerates and has high viscoelasticity, which effectively improved casein's emulsifying activity (8.66 ± 0.17 m2/g). After the casein/GA complexes microencapsulation, a higher viable count was detected after gastrointestinal digestion in vitro, and the activity of L. plantarum is more stable (about 7.51 log CFU/mL) during 35 days of storage at 4 °C. The results of study will help to design lactic acid bacteria encapsulation systems based on the GIT environment for the oral delivery strategy.

Enhanced production rate of probiotic Enterococcus faecium A028 by repeated batch solid-state fermentation and its survival under hot air drying with cell-protective agents

Probiotic viability is an important aspect of animal feed additives. Enterococcus faecium A028, a potential probiotic, was isolated from the intestinal digestion track of chicken. Production rate of E. faecium A028 probiotic inoculum with high total viable cell count (TVC) was enhanced using repeated batch solid-state fermentation (RB-SSF). The probiotic strain grew well in soybean meal (SBM) with average TVC of over 9 LogCFU/g in all RB-SSF experiments. Average specific growth rate of E. faecium A028 in fermented SBM (FSBM) was 50% repeated batch ratio (RB ratio) for 0.37 h−1, and higher than the batch process (0.33 h−1). Probiotic inoculum production rate was enhanced by increasing the RB ratio. Highest total TVC production rate was 128.15 LogCFU/h at 90% RB ratio, while average TVC was 9.09 LogCFU/g. Total production of FSBM at 90% RB ratio was 1.6 times higher than batch fermentation. Different protective agents were investigated to increase the survival of E. faecium A028 during hot air drying. Maltodextrin (MTD) provided the highest survival rate at 83.9% during 24 h of drying. RB-SSF effectively enhanced the production rate of probiotic strain cultivation in SBM, while MTD acted as a cell-protective agent and maintained the survival of E. faecium A028 during thermal drying.

Development of Value-Added Butter by Incorporating Whey Protein Hydrolysate-Encapsulated Probiotics.

The probiotic foods market is growing exponentially; however, probiotics' survivability and interaction with product attributes pose major challenges. A previous study of our lab developed a spray-dried encapsulant utilizing whey protein hydrolysate-maltodextrin and probiotics with high viable counts and enhanced bioactive properties. Viscous products such as butter could be suitable carriers for such encapsulated probiotics. The objective of the current study was to standardize this encapsulant in salted and unsalted butter, followed by storage stability studies at 4 °C. Butter was prepared at a lab-scale level, and the encapsulant was added at 0.1% and 1%, followed by physiochemical and microbiological characterization. Analyses were conducted in triplicates, and means were differentiated (p < 0.05). The viability of probiotic bacteria and the physicochemical characteristics of the butter samples with 1% encapsulant were significantly higher as compared to 0.1%. Furthermore, the 1% encapsulated probiotics butter variant showed a relatively higher stability of probiotics ratio (LA5 and BB12) than the control with unencapsulated probiotics during storage conditions. Although the acid values increased along with a mixed trend of hardness, the difference was insignificant. This study thus provided a proof of concept for incorporating encapsulated probiotics in salted and unsalted butter samples.

Different parts from the whole red beet (Beta vulgaris L.) valorization with stimulatory effects on probiotic lactobacilli and protection against gastrointestinal conditions

This study evaluated the effects of freeze-dried red beet (Beta vulgaris L.) root (FDBR) and stem/leaves (FDBSL) on the growth and metabolic activities of the probiotics Lactobacillus acidophilus La-05, Lacticaseibacillus casei 26, and Lismosilactobacillus fermentum 296, as well as on their survival and physiological states when exposed to simulated gastrointestinal conditions (SGIC). The changes in the contents of phenolic compounds and antioxidant activity of FDBR and FDBSL when exposed to SGIC were also evaluated. FDBR and FDBSL had high contents of soluble (5.25 and 11.10 g/100 g) and insoluble fiber (21.43 and 37.03 g/100 g), pectins (8.45 and 9.51 g/100 g), betalains (3.36–28.99 g/100 g), and a variety of phenolic compounds. FDBR and FDBSL stimulated the growth of the probiotic strains with high viable counts (>9 log CFU/mL), the production of acetic, butyric, lactic, and propionic acids, and alterations in the contents of phenolic compounds during 72 h of cultivation. FDBR and FDBSL had positive prebiotic activity scores on the tested probiotics (≥0.17) linked to selective stimulatory effects. FDBR and FDBSL increased the survival and maintenance of active physiological functions in the probiotic during exposure to SGIC. The contents of phenolic compounds and the antioxidant activity of FDBR and FDBSL increased after exposure to the stomach conditions, while the antioxidant activity decreased after exposure to intestine conditions. The stimulatory and protective effects of FDBR and FDBSL on probiotic strains could be associated with their dietary fiber and phenolic compound contents, which could be exploited in the formulation of functional foods or dietary supplements.

Synergistic combination of cryoprotectants for high freeze-dried survival rate and viable cell counts of Streptococcus thermophilus

Vacuum freeze-drying is one of the common methods to prepare probiotic powder. However, the low temperature and low moisture content could lead to the death of probiotics. The method of adding cryoprotectants is efficient to improve the survival rate of probiotics during vacuum freeze-drying. The synergistic combination of different cryoprotectants could play a better protective effect. However, the principle of the synergistic combination of different cryoprotectants during vacuum freeze-drying is not clear. In this study, literature review and analysis were firstly used to reveal commonly used cryoprotectants for coccus. Taking the price of cryoprotectants into account, the combination is preliminarily determined as sucrose/skim milk/sodium glutamate. Then, taking Streptococcus thermophilus 937 as the research target strain, the effect of this cryoprotectant combination was verified by a single-factor screening experiment and concentration optimization of cryoprotectants. It was found that the preferred cryoprotectant combination for Streptococcus thermophilus 937 is 6% sucrose/8% skim milk/4% sodium glutamate, with the freeze-dried survival rate and viable counts being 90.59% and 1.78 × 1011CFU/g, respectively. Meanwhile, this cryoprotectant combination also had a good protective effect on the other two cocci, Streptococcus thermophilus Grx02 and Enterococcus faecium 218. This result might have guiding and reference significance on the vacuum freeze-drying of coccus.

Enzymatic Activity and Horizontal Gene Transfer of Heavy Metals and Antibiotic Resistant Proteus vulgaris from Hospital Wastewater: An Insight.

Globally, the issue of microbial resistance to medicines and heavy metals is getting worse. There are few reports or data available for Proteus vulgaris (P. vulgaris), particularly in India. This investigation intends to reveal the bacteria's ability to transmit genes and their level of resistance as well. The wastewater samples were taken from several hospitals in Lucknow City, India, and examined for the presence of Gram-negative bacteria that were resistant to antibiotics and heavy metals. The microbial population count in different hospital wastewaters decreases with increasing concentrations of metal and antibiotics. Among all the examined metals, Ni and Zn had the highest viable counts, whereas Hg, Cd, and Co had the lowest viable counts. Penicillin, ampicillin, and amoxicillin, among the antibiotics, demonstrated higher viable counts, whereas tetracycline and erythromycin exhibited lower viable counts. The MIC values for the P. vulgaris isolates tested ranged from 50 to 16,00 μg/ml for each metal tested. The multiple metal resistance (MMR) index, which ranged from 0.04 to 0.50, showed diverse heavy metal resistance patterns in all P. vulgaris isolates (in the case of 2-7 metals in various combinations). All of the tested isolates had methicillin resistance, whereas the least number of isolates had ofloxacin, gentamycin, or neomycin resistance. The P. vulgaris isolates displayed multidrug resistance patterns (2-12 drugs) in various antibiotic combinations. The MAR indexes were shown to be between (0.02-0.7). From the total isolates, 98%, 84%, and 80% had urease, gelatinase, and amylase activity, whereas 68% and 56% displayed protease and beta-lactamase activity. Plasmids were present in all the selected resistant isolates and varied in size from 42.5 to 57.0 kb and molecular weight from 27.2 to 37.0 MD. The transmission of the antibiotic/metal resistance genes was evaluated between a total of 7 pairs of isolates. A higher transfer frequency (4.4 × 10-1) was observed among antibiotics, although a lower transfer frequency (1.0 × 10-2) was observed against metals in both the media from the entire site tested. According to exponential decay, the population of hospital wastewater declined in the following order across all sites: Site II > Site IV > Site III > Site I for antibiotics and site IV > site II > site I >site III for metal. Different metal and antibiotic concentrations have varying effects on the population. The metal-tolerant P. vulgaris from hospital wastewater was studied in the current study had multiple distinct patterns of antibiotic resistance. It could provide cutting-edge methods for treating infectious diseases, which are essential for managing and assessing the risks associated with hospital wastewater, especially in the case of P. vulgaris.

Characterization of the effects of binary probiotics and wolfberry dietary fiber on the quality of yogurt

The effects of binary probiotics (Lacticaseibacillus casei CGMCC1.5956 and Lactiplantibacillus plantarum subsp. plantarum CGMCC 1.5953) in conjunction with wolfberry dietary fiber (WDF) on yogurt quality were investigated in this study. d-fructose, β-d-glucose, 6-acetyl-d-glucose, and 1-ketose in WDF significantly improved syneresis, apparent viscosity, and elastic behavior of yogurt. Binary probiotics were more suitable for fermenting WDF yogurt than single probiotics, resulting in a higher viable count (9.39 lg (CFU/mL)) and unique flavor. Binary probiotics can promote the production of tyrosol by L. casei 56 through the tyrosine metabolic pathway, thereby enhancing the resistance of L. casei 56 and L. plantarum 53 to their environment and promoting growth. Pyridine, 2,3,4,5-tetrahydro- and prenol might be responsible for the high odor scores in the sensory evaluation of WDF yogurt prepared using binary probiotics. In summary, combining binary probiotics and WDF can significantly improve yogurt quality and add value to the final product.

Sheep Milk Symbiotic Ice Cream: Effect of Inulin and Apple Fiber on the Survival of Five Probiotic Bacterial Strains during Simulated In Vitro Digestion Conditions.

We conducted a study to determine the survival of bacterial cells under in vitro digestion. For this purpose, ice cream mixes were prepared: control, with 4% inulin, 2.5% inulin and 1.5% apple fiber and 4% apple fiber. Each inoculum (pH = 4.60 ± 0.05), containing 9 log cfu g-1 bacteria, at 5% (w/w) was added to the ice cream mixes (Lacticaseibacilluscasei 431, Lactobacillus acidophilus LA-5, Lacticaseibacillus paracasei L-26, Lacticaseibacillusrhamnosus, Bifidobacterium animalis ssp. lactis BB-12) and fermentation was carried out to pH 4.60 ± 0.05. The in vitro digestion method simulated the stages of digestion that occur in the mouth, stomach and small intestine under optimal controlled conditions (pH value, time and temperature). At each stage of digestion, the survival rate of probiotic bacteria was determined using the plate-deep method. As expected, in the oral stage, there was no significant reduction in the viability of the probiotic bacteria in any ice cream group compared to their content before digestion. In the stomach stage, Bifidobacterium animalis ssp. lactis BB-12 strain had the highest viable counts (8.48 log cfu g-1) among the control samples. Furthermore, a 4% addition of inulin to ice cream with Bifidobacterium BB-12 increased gastric juice tolerance and limited strain reduction by only 16.7% compared to the number of bacterial cells before digestion. Regarding ice cream samples with Bifidobacterium BB-12, replacing part of the inulin with apple fiber resulted in increased survival at the stomach stage and a low reduction in the bacterial population of only 15.6% compared to samples before digestion. At the stomach stage, the positive effect of the addition of inulin and apple fiber was also demonstrated for ice cream samples with Lacticaseibacilluscasei 431 (9.47 log cfu g-1), Lactobacillus acidophilus LA-5 (8.06 log cfu g-1) and Lacticaseibacillus paracasei L-26 (5.79 log cfu g-1). This study showed the highest sensitivity to simulated gastric stress for ice cream samples with Lacticaseibacillusrhamnosus (4.54 log cfu g-1). Our study confirmed that the 4% addition of inulin to ice cream increases the survival rate of L. casei and Bifidobacterium BB-12 in simulated intestinal juice with bile by 0.87 and 2.26 log cfu g-1, respectively. The highest viable count in the small intestine stage was observed in ice cream with L. acidophilus. The addition of inulin increased the survival of L. rhamnosus by 10.8% and Bifidobacterium BB-12 by about 22% under conditions of simulated in vitro digestion compared to their control samples. The survival rates of L. casei and L. paracasei were also highly affected by the 4% addition of apple fiber, where the increase under gastrointestinal passage conditions was determined to range from 7.86-11.26% compared to their control counterparts. In comparison, the lowest survival rate was found in the control ice cream with L. rhamnosus (47.40%). In our study at the intestinal stage, only five ice cream groups: a sample with 4% inulin and L. acidophilus, a control sample with Bifidobacterium BB12, a sample with 2.5% inulin and 1.5% apple fiber with Bifidobacterium BB12, a control sample with L. rhamnosus, a sample with 4% fiber and L. rhamnosus reported bacterial cell counts below 6 log cfu g-1 but higher than 5 log cfu g-1. However, in the remaining ice cream groups, viable counts of bacterial cells ranged from 6.11 to 8.88 log cfu g-1, ensuring a therapeutic effect. Studies have clearly indicated that sheep milk ice cream could provide a suitable matrix for the delivery of probiotics and prebiotics and contribute to intestinal homeostasis. The obtained results have an applicative character and may play an essential role in developing new functional sheep milk ice cream.

Extractive Fermentation as A Novel Strategy for High Cell Mass Production of Hetero-Fermentative Probiotic Strain Limosilactobacillus reuteri

This study reports on a novel technique to enhance the high cell mass and viable cell counts of the heterofermentative probiotic strain, Limosilactobacillus reuteri. This is the first report on the cultivation of L. reuteri, which was incorporated with weak base anion-exchange resins to remove the accumulating lactic acid in the fermentation broth. Two anion-exchange resins—Amberlite IRA 67 and IRA 96—were found to have a high adsorption capacity with lactic acid. Batch fermentation and fed-batch cultivation were further analyzed using IRA 67 resins, as this application resulted in a higher maximum number of viable cells. The in situ application of anion-exchange resins was found to create shear stress, and thus, it does not promote growth of L. reuteri; therefore, an external and integrated resin column system was proposed. The viable cell count from batch fermentation, when incorporated with the integrated resin column, was improved by 71 times (3.89 × 1011 ± 0.07 CFU mL−1) compared with control batch fermentation (5.35 × 109 ± 0.32 CFU mL−1), without the addition of resins. The growth improvement was achieved due to the high adsorption rate of lactic acid, which was recorded by the integrated IRA 67 resin system, and coupled with the stirred tank bioreactor batch fermentation process.

Bioherbicide Effect of Effluent from Processed Manihot esculentus Tubers

Effluents from processed bitter cassava (Manihot esculentus) tubers as bioherbicide was applied on the leaves of Beans, Broom weed, Maize, and Itch grass and investigated. Quantitative and qualitative characterization of microorganisms (bacteria and fungi) was done both in effluent and test soil. Mineral analysis using atomic absorption spectrum (AAS), cyanide quantification in the effluent, and quantification of chlorophyll (a and b) from the leaves of test plants (Beans, Broom weed, Maize, and Itch grass) were carried out. The result from the microbial characterization of effluent, test soil, and control soil revealed the effluent had the highest microbial load. The isolated bacteria were Staphylococcus spp, Bacillus spp, Lactobacillus, and E. coli. Test soil had 16.13% Staphylococcus, 9.68% Bacillus spp, 16.13% Lactobacillus, and 6.45% E. coli. The isolated fungi were Saccharomyces, Mucor, and Aspergillus in the effluent, while Saccharomyces and Mucor were in the test soil and only Aspergillus in the control soil.The fungal count revealed a high total viable count (TVC) in the effluent (7.0×104 cfu/ml) followed by test soil (6.6×104 cfu/ml) while control soil had the least (4.5%×104 cfu/ml). Cyanide analysis of effluent revealed 1.0 mg/ml, while metal analysis revealed potassium (40.221 mg/kg), sodium (32.009 mg/kg), Manganese (0.057 mg/kg) and Copper (-0.004mg/kg).The chlorophyll(a and b) concentration expressed in µg/mlof the experimented plants (Beans, Broom weed, Maize, and Itchgrass) further revealed a significant (p≤0.05) decrease concerning the volume of effluent applied (50 ml and 25 ml).Dicotyledonous plants; beans (0.461 + 0.025 and 0.609 + 0.013chlorophyll (a) compared to a control of 7.698+ 0.100.Chlorophyll(b) on the other hand revealed 5.507 + 0.141and 11.599 + 0.282 when compared with control of 16.426 + 0.016). Broom weed (0.291 + 0.071 and 0.457 + 0.068 for chlorophyll (a) when compared to the control with 0.595 + 0.071 and 1.549+0.141 and 1.683+0.353 for chlorophyll(b) when compared to the control with 22.252 + 0.282. Other plants analyzed revealed various significant (p≤0.05) decreased levels of chlorophyll (a and b). All the results revealed this effluent may be selectively used as a potential bioherbicide especially when applied to the leaves.

Dynamics of microbiota in the imported beef primal cuts during storage at different chilled temperatures.

Primal cuts of Australian beef transported by sea were stored under different chilled temperatures (0, 2, and 4 °C) for 6 weeks in different packaging conditions (aerobic or anaerobic packaging). The number of microorganisms and the transition of the microbiota were investigated using culture methods and amplicon sequencing. After 6 weeks of storage, the beef tended to show a high total viable count under aerobic packaging conditions and a high lactic acid bacteria count under anaerobic packaging conditions. The result of amplicon sequencing analysis showed that different beef samples had different predominant bacterial groups. Moreover, at high storage temperatures, Serratia sp. having high putrefactive activity showed increased abundance, while at low storage temperatures, Lactobacillus sp. showed increased abundance. Thus, differences in the packaging conditions and distribution temperatures after import affect the number of bacteria and the type of microorganisms in the Australian beef primal cuts, which may affect their quality.