Log UFC Research Articles

Encapsulated Bifidobacterium BB-12 addition in a concentrated lactose-free yogurt: Its survival during storage and effects on the product's properties

This work aims to manufacture a new concentrated lactose-free probiotic yogurt. For this purpose, the probiotic Bifidocaterium BB-12 was incorporated in a concentrated lactose-free yogurt, both in its free form and previously encapsulated. Previous cell encapsulation was performed using the spray-drying technique with the following wall materials: lactose-free milk, lactose-free milk and inulin, and lactose-free milk and oligofructose. Thus, three different probiotic powders were obtained and added separately to three fractions of concentrated lactose-free yogurt. The probiotic survival of both powders and yogurts was evaluated during refrigerated storage. Likewise, the viability of starter cultures in yogurt (Lactobacillus bulgaricus and Streptococcus thermophilus) was controlled. In addition, the physicochemical properties of the four yogurts were also measured (color, pH and acidity, and texture properties). All three powders showed good probiotic viability (>8 log CFU g−1) throughout 120 days of storage at 4 °C. In turn, yogurt formulations (with the addition of powders or free bifidobacteria) presented probiotic viability above 7 log CFU g−1 after storage; as well as the starter cultures (>8 log UFC g−1). Yogurt with probiotic powder from lactose-free milk showed a more yellowish color; however, these differences would not be detected by the human eye (ΔE < 3.00). The yogurt with bifidobacteria free cells showed a greater post-acidification process (pH 4.18 to 4.02 and titratable acidity 1.52 to 1.89). It was not observed differences for firmness values of yogurt with free cells addition and yogurt with lactose-free milk and oligofructose powder addition. A slight significant decrease in the cohesiveness was observed in the yogurt elaborated with bifidobacteria free cells. The gumminess showed fluctuating values between all concentrated lactose-free yogurts. At the end of this study, we conclude that these probiotic powders can be incorporated into innovative lactose-free yogurts.

Komagataella pastoris KM71H modulates neuroimmune and oxidative stress parameters in animal models of depression: A proposal for a new probiotic with antidepressant-like effect

Many studies have suggested that imbalance of the gut microbial composition leads to an increase in pro-inflammatory cytokines and promotes oxidative stress, and this are directly associated with neuropsychiatric disorders, including major depressive disorder (MDD). Clinical data indicated that the probiotics have positive impacts on the central nervous system and thus may have a key role to treatment of MDD. This study examined the benefits of administration of Komagataella pastoris KM71H (8 log UFC·g–1/animal, intragastric route) in attenuating behavioral, neurochemical, and neuroendocrine changes in animal models of depressive-like behavior induced by repeated restraint stress and lipopolysaccharide (0.83 mg/kg). We demonstrated that pretreatment of mice with this yeast prevented depression-like behavior induced by stress and an inflammatory challenge in mice. We believe that this effect is due to modulation of the permeability of the blood-brain barrier, restoration in the mRNA levels of the Nuclear factor kappa B, Interleukin 1β, Interferon γ, and Indoleamine 2 3-dioxygenase, and prevention of oxidative stress in the prefrontal cortices, hippocampi, and intestine of mice and of the decrease the plasma corticosterone levels. Thus, we conclude that K. pastoris KM71H has properties for a new proposal of probiotic with antidepressant-like effect, arising as a promising therapeutic strategy for MDD.

Effects of combined application of high‐pressure processing and active coatings on phenolic compounds and microbiological and physicochemical quality of apple cubes

In recent years the use of high-pressure processing (HPP) of fruit products has steadily increased due to its antimicrobial effectiveness and the retention of nutritional and quality attributes compared to conventional thermal technologies. Edible coatings are already being used to enhance the quality of minimally processed fruits. Thus, apple cubes (AC) and alginate-vanillin-coated apple cubes (AVAC) were subjected to HPP (400 MPa/5min/35 °C). The microbiological and physicochemical parameters were evaluated and the bioactive compounds were monitored before and after HPP of apple cubes. Also, an in vitro gastrointestinal digestion (GID) was conducted. HPP left L. monocytogenes counts below the detection limit (2log UFC g-1 ), regardless of the presence of coating. For E. coli, HPP + active coating showed a synergism affording the greatest reduction (>5log) for AVAC-HPP. Firmness was maintained in AVAC-HPP samples, while AC-HPP samples suffered reductions of 35%. Colour attributes were also better retained in AVAC-HPP samples. In general, HPP led to a decrease in phenolic compounds. Regarding the effects of GID, vanillin-based active coating exerted a protective effect on some phenolics. Thus, p-coumaroylquinic acid concentration was maintained for AVAC and AVAC-HPP during GID. Epigallocatechin, the compound with the highest concentration in apple cubes, increased for AVAC (106%) and AVAC-HPP (57%). Also, phloridzin concentration increased for AVAC-HPP (17%). At the end of GID, procyanidin B1 and epigallocatechin were the main phenolic compounds for all samples, AVAC showing the highest concentration. This work demonstrates that the combined application of HPP and active coatings on apple cubes could be used to obtain a safe and good-quality product. © 2021 Society of Chemical Industry.

Symbiotic drink based on Brazil nuts (Bertholletia excelsa H.B.K): production, characterization, probiotic viability and sensory acceptance

ABSTRACT: Brazil nut is a typical oilseed from the Amazon region, of great economic and cultural importance. Due to its high nutritional value, it is interesting to be used as a matrix for new products’ development. Thus, the present study aimed to develop and characterize a drink based on Brazil nuts fermented by Lactobacillus casei and added with inulin. After formulated, the drink was pasteurized, fermented, maturated, and stored under refrigeration for 28 days. Physical, chemical, microbiological, and sensory analyzes were performed before and after fermentation, at 7-day intervals. There was maintenance in the content of lipids and proteins and reduction in the concentrations of fibers, ash, total carbohydrates, and moisture. The fermented drink pH decreased significantly during storage, while the acidity and the soluble solids content increased from the 14th day. Regarding the color, there were significant changes in all parameters analyzed. In the fermented drink, the development of molds and yeasts, total and thermotolerant coliforms, and Salmonella were not verified, while the control drink deteriorated after 7 days. The probiotic L. casei had count ranging from 9.48 to 8.59 log CFU mL-1 during the 28 days. When exposed to in vitro gastrointestinal conditions, L. casei significantly reduced its concentration. However, it reached the enteric phase with counts greater than 6.00 log UFC mL-1. Sensorially, the drink reached intermediate scores (between 5.41 and 6.02). Therefore, the use of Brazil nuts proved to be viable for the development of a product free of animal-origin components, symbiotic, and of outstanding nutritional quality.

Microbiota of Sardinian Goat's Milk and Preliminary Characterization of Prevalent LAB Species for Starter or Adjunct Cultures Development.

This work was performed to study the microbiota of raw goat's milk (67 samples) collected in different areas of Sardinia, in order to select autochthonous lactic acid bacteria (LAB) strains for use in goat cheese manufacturing. Total mesophilic bacteria ranged between 105 and 107 cfu/mL; mean counts of Enterobacteriaceae did not exceed 4 log cfu/mL whereas those of E. coli and coagulase-positive staphylococci were lower than 1.5 and 2 log ufc /ml, respectively. Neither Salmonella spp. nor Listeria monocytogenes were recovered. The numbers of total LAB were in the range from 104 to 107 cfu/mL and mean yeasts counts varied between 103 and 105 cfu/mL. The most frequently isolated LAB species were Lactococcus lactis subsp. lactis and Lactobacillus paracasei. The presence of Enterococcus faecium was also noteworthy. The in vitro study of some functional characteristics related to technological properties of the strains belonging to these species allowed to point out some strains possessing good potential for use as adjunct or starter cultures in the production of cheese.

Viability of probiotic bacteria in tropical mango juice and the resistance of the strains to gastrointestinal conditions simulated in vitro

This study evaluated the viability of Lactobacillus acidophilus La-05, Lactobacillus plantarum LP299v and Lactobacillus rhamnosus GG in tropical mango juice, the resistance of the strains to gastrointestinal conditions simulated in vitro and the microbiological, physicochemical and sensory characteristics of the products obtained. The viabilities of L. rhamnosus GG and L. plantarum LP299v were greater than 7.96 log CFU mL-1 and 7.74 log CFU mL-1, respectively, during the 28 days of storage at 8 °C. However, there was a reduction (p &lt; 0.05) in the viability of L. acidophilus La-5 after 21 days of storage, with counts of 3.81 log UFC mL-1. The parameters of pH, total soluble solids, luminosity (L*) and the color coordinates, a* and b*, did not differ between the treatments. However, the pH and acidity varied during the storage time, probably due to the fermentative action of the microorganisms. For the in vitro gastrointestinal resistance test, there was a difference in the gastric phase for enteric phases I and II. The mean viability of the microorganisms in the gastric phase was 5.11 log CFU mL-1, decreasing to 4.02 and 3.97 log CFU mL-1 in enteric phases I and II, respectively. Juices containing L. rhamnosus GG and L. plantarum LP299 were evaluated sensorially, presenting good acceptability. The results suggest that the tropical mango juice was a good carrier matrix for L. rhamnosus GG and L. plantarum LP 299v, being well accepted and therefore an alternative for populations with dietary restrictions.

Frequency in the supply of Lactobacillus influence its probiotic effect for yellow tail lambari

ABSTRACT: The aim of this research was to evaluate the changes in intestinal tract microbiota, hematological parameters and zootechnical indexes of yellowtail lambaris (Astyanax bimaculatus) fed with different probiotic supply frequencies (Lactobacillus spp.). Lambaris (1,200) were distributed in twelve boxes, divided in three treatments, 100% supply; 25% and 0% (control) of feeds supplemented with probiotic. After 87 days, fish fed with supplemented diet, regardless of frequency (100% and 25%), showed an increase in the total lactic acid bacteria count of 7.99±0.15 log CFU mL-1 and 7.04±1, 29 log UFC mL-¹ respectively, in the intestinal tract and decrease of Pseudomonas spp. in both 100% and 25% (4.09±0.84log UFC mL-1 and 4.00±1.12log UFC mL-1, respectively) in relation to the control treatment (6.74±1.04log UFC mL-1). Fish fed with 100% of diets supplemented with probiotics had a higher leukocyte count (47.7±6.7x103μL-1), lymphocytes (36.0±2.6x103μL1), monocytes (12.0±4.2x103μl-1), as well as higher mean final weight (10.60±0.89g) and weekly growth rate (0.80±0.08g.week-1) than the other treatments (25% of probiotic offered and control). Probiotic (Lactobacillus spp.) offered in 25% of feeds (or more) alters the yellowtail lambari microbiota (A. bimaculatus); however, must be offer in 100% of feeds to improve the hematology profile and productive performance.

EFECTO DEL SECADO POR LECHO FLUIDIZADO SOBRE LAS PROPIEDADESFISICOQU ́IMICAS Y MICROBIOL ́OGICAS DE QUESO FRESCO MEXICANO

Artisan Mexican fresh cheese traditionally made from raw milk, is often salted and susceptible to changes caused by enzymes and spoilage microorganisms, generating alterations in the product at the sensory and nutritional level. The main purpose of this study was to evaluate the effect of fluidized bed drying on physicochemical and microbiological properties of Mexican fresh cheese. A 23+2(3)+1 rotatable central composite design was used to establish the fluidized bed drying conditions. The factors were drying time 60, 90 and 120 min, drying air temperature 50, 60 and 70 °C, and particle size 0.5, 2 and 3.5 cm. The analysis of variance indicated that time and drying temperature aected significantly (p ± 0.10) on response variables of dried cheese. According to results the lowest values at the end of the process of moisture content, water activity, color dierence, NaCl, fat, energy consumption and production cost were: 0.31%, 0.22, 6.63, 1.50%, 38.07%, 0.5293 kW and 72.11 $·Kg-1 respectively. The highest values for viability, protein content and production were: 6.66 log UFC·g-1 of lactobacillus, 39.45% and 0.0556 Kg·h-1 respectively

Microbiological characterization using combined culture dependent and independent approaches of Casizolu pasta filata cheese.

Casizolu is a traditional Sardinian (Italy) pasta filata cheese made with cow raw milk belonging to Sardo-Modicana and/or Bruno-Sarda breeds added with natural whey starter. This work aims to describe the traditional technology of this product and to evaluate the microbial groups/species involved in the first month of ripening. Raw milk, curd after stretching and Casizolu cheese samples from two different farmsteads were subjected to enumeration of microbial groups, isolation and genotypic characterization of isolates and PCR temporal temperature gel electrophoresis (TTGE) analysis. The counts of lactobacilli and lactococci groups in raw milk were about 5-6 log UFC ml(-1) of milk. These counts tended to increase in curd and cheeses, reaching values higher than 8 log UFC g(-1) of cheese. Culture dependent and independent approaches employed in this work highlighted the fundamental role of Lactococcus lactis subsp. lactis, Streptococcus thermophilus and Lactobacillus paracasei in the manufacture and ripening of Casizolu cheese. Other species frequently isolated were Enterococcus durans, Enterococcus faecium, Enterococcus italicus while Enterococcus lactis, Streptococcus parauberis, Lactobacillus plantarum, Lactobacillus pentosus, Lactobacillus brevis, Lactobacillus fermentum and Lactococcus raffinolactis were isolated occasionally. Lactococcus lactis subsp. lactis, Strep. thermophilus and Lact. paracasei were the principal bacterial species involved in the Casizolu cheese manufacturing and ripening. For the first time, Ent. italicus and Ent. lactis were isolated in the pasta filata cheese. This study shows the first data on microbial groups and species involved in the manufacture of Casizolu cheese and highlights the role of Lact. paracasei and Enterococcus spp. from the earliest stages of ripening cheese; furthermore, provides evidence that raw milk cheese is a source of new strains and therefore a reservoir of microbial biodiversity.

Optimisation of the peracetic acid washing disinfection of fresh‐cut strawberries based on microbial load reduction and bioactive compounds retention

SummaryTotal microbial count reduction (TMR), total anthocyanins (TAR), and ascorbic acid retention (AAR) after the operation at different PAA concentrations (0–100 mg L−1), contact times (10–120 s), and temperatures (4–40°C) were used for multiple optimisation using Derringer′s desirability function. Two optimization scenarios (OP 1 and OP 2) were studied. OP 1 was proposed with the goal to maximize TMR with 90% TAR and AAR; and OP 2 maximizing TAR and AAR with TMR of 2 log UFC g−1. The optimized variable levels obtained were the following: 100 mg L−1 PAA, 24 °C and 50 s for OP 1 and 20 mg L−1 PAA, 18 °C and 52 s for OP 2. Additional validation experiments showed agreement between predicted and experimental results. OP 2 conditions are recommended to fresh‐cut strawberries washing disinfection because of an acceptable TMR, higher TAR and AAR, better sensory attributes, and the economic convenience of lesser PAA consumption.

Antagonistic Effect of the Lactic Bacteria Isolated from the Camel Milk on Staphylococcus aureus in Yoghourt Manufacturing

This paper deals with the lactic bacteria found in the raw camel milk producing antibacterial substances. Samples of milk were obtained from female camels of herds from nomads living in the south of Algeria. The antibacterial activity of the bacteria was tested on Staphylococcus aureus strains and to highlight this activity in a yoghourt for therapeutic purpose.Among the seven (07) strains of lactic bacteria which were isolated from camel milk Lb. fermentum (Lc17) presented the highest antagonistic effect on S. aureus. After incorporation in the yoghourt ,It was verified that there was no interaction between the lactic ferments of yoghourt and Lb. fermentum and no modification of the acidity. However the realization of a yoghourt containing Lb. fermentum with shown a total inhibition of Staphylococcus aureus to a load 5,87 log UFC compared to that of yoghourt made up exclusively of lactic leavens, after 4 hours of incubation in mixed culture.

IDENTIFICACIÓN DE ALGUNAS ESPECIES DE MICROORGANISMOS BENÉFICOS EN LA RIZOSFERA DE GERBERA Y SU EFECTO EN LA PRODUCTIVIDAD

We identify the mycorrizal fungi (HMA) species living in the rhizosphere of Gerbera jamesonii cv. Bolus and the plant growth promoting bacterial (PGBP) genera attracted by those radical exudates. The chemoattraction of some plant growth promoting bacterial toward root exudates of this crop was also evaluated. The espermospher model was used for bacterial isolation and Collector tubes and the chemotaxis camera modified for the evaluation of the chemotactic effect of those radical exudates. To the bacterial characterization, was carried out micromorphological determinations (mobility, endosporas presence and others) and cultural determinations (forms, size, opacity and others). Five replications per treatment were used three times. Five micorrizal fungi species and four plant growth promoting bacterial genera attracted by gerbera radical exudates were found, almost Glomus genus were predominant, being Glomus hoi like specie the principal one. Pseudomonas (30 %) was the predominant genus among bacterials. Taking into account these results, adult plants were established in recipients of five litres of capacity, were inoculated using red ferralitic soil mixed with cow dung in a proportion of 2:1. The evaluated variables were yield and floral capitulum diameter and root colonization, finding that inoculated plants with Glomus hoi like had more root occupation (1.91 %), more mycorrizal fungus espores (5.6 espores·ml-1) and bacterial (8.2 log UFC·ml-1) in the rhizosphere and more flowers (35).

Desenvolvimento e avaliação de uma cepa knockout de Brucella abortus obtida pela deleção do gene virB10

Brucella spp. são bactérias gram-negativas, intracelulares facultativas que são patogênicas para muitas espécies de mamíferos causando a brucelose, uma zoonose difundida mundialmente. Por isso a busca de alternativas de controle mais eficientes se faz necessário como o desenvolvimento de novas cepas que possam ser testadas como potenciais imunógenos. Neste estudo realizou-se a deleção do gene virB10 da cepa S2308 de Brucella abortus gerando uma cepa knockout provavelmente incapaz de produzir a proteína nativa correspondente. O gene virB10 faz parte de um operon que codifica para um sistema de secreção do tipo IV, essencial para a sobrevivência intracelular e multiplicação da bactéria em células hospedeiras. A deleção foi realizada pela construção do plasmídeo suicida pBlue:virB10:kan e eletroporação deste em células eletrocompetentes de B. abortus S2308, ocorrendo a troca do gene selvagem pelo gene interrompido, com o gene de resistência a canamicina, por recombinação homóloga dupla. Camundongos BALB/c foram inoculados com as cepas S19, RB-51, ΔvirB10 de B. abortus e B. abortus S2308 selvagem; os resultados demonstraram que camundongos BALB/c inoculados com S19 e camundongos BALB/c inoculados com S2308 apresentaram queda mais rápida de linha de tendência, quando comparadas aos demais grupos, para recuperação bacteriana (RB) e peso esplênico (PE) respectivamente. Os grupos que receberam ΔvirB10 S2308 de B. abortus e RB-51 demonstraram comportamento semelhante para ambas as características. Na sexta semana após a inoculação, os resultados para RB (log de UFC ± desvio padrão) e PE (peso esplênico ± desvio padrão), respectivamente, mostraram: grupos inoculados com as cepas S2308 (4,44±1,97 e 0,44±0,11), S19 (1,83±2,54 e 0,31±0,04), RB-51 (0,00±0,00 e 0,20±0,01) e ΔvirB10 S2308 (1,43±1,25 e 0,19±0,03). Considerado o clearance bacteriano, todos os grupos diferiram estatisticamente do grupo que recebeu S2308 (p&lt;0,0001), o grupo inoculado com ΔvirB10 S2308 de B. abortus foi semelhante ao grupo S19 (p=0,4302) e diferente do grupo RB-51 (p=0,0063). A avaliação da persistência revelou que o gene virB10 é essencial para a manutenção da virulência da bactéria. Os resultados obtidos possibilitarão que outras pesquisas sejam realizadas avaliando o potencial imunogênico desta cepa mutante.

Determinación cuantitativa de proteasas de bacterias psicrotróficas aisladas de leche cruda

El uso generalizado de la refrigeración de la leche cruda ha contribuido a mantener la calidad de ésta, pero ha traído como consecuencia la selección de una carga psicotrófica, que durante su desarrollo produce enzimas termoresistentes responsables, en parte, del deterioro de productos de larga vida. Este estudio se diseñó para la cuantificación de la actividad proteolítica de seis microorganismos que corresponden a Pseudomonas fluorescens R12 y R13, Pseudomonas putida R20, Micrococcus luteus R16, Bacillus circulans R5 y Serratia liquefasciens R4, aislados y caracterizados en la leche cruda.Las seis cepas fueron cultivadas en caldo leche al 11%. Para las curvas de crecimiento, los datos experimentales se ajustaron al modelo de Baranyi. La Pseudomonas putida R20 presentó mejor cinética de crecimiento con _máx de 0,1066h-1 y un tiempo de duplicación de 6,5023h. En la determinación de la actividad proteolítica, según Hübner, se estableció que Bacillus circulans R5 a 5ºC produjo en la hora 4 de fermentación la mayor cantidad de proteasas (3,618UP/mL) en comparación con las demás cepas de estudio.Finalmente se estableció que la temperatura donde existe mayor actividad proteolítica fue 5ºC, que al incrementarse provoca una disminución considerable en la producción de proteasas.

Treatment for small polluted rivers: Design and performance of an experimental structure

In view of the economic reality of developing countries, it will not be possible to build all the necessary wastewater treatment plants (WWTP) needed to control the pollution of their rivers in the next 20 years. Therefore, low-cost alternative technologies must be developed to restore the water quality of polluted rivers. It is well-known that the self-purification cycle in nature uses several biotic and abiotic processes to restore polluted water to its former pristine quality. This cycle has been surpassed in many rivers due to continuous discharges of wastewater into them. A low-cost structure that will enhance the water quality in small polluted rivers is proposed and can be constructed in situ, based on three conditions: Disruption of plug flow, flow velocity and support material for bacterial growth. The design of the experimental stage of this structure can control slope, water flow, length, support material and the number of locks. Two 175m-long experimental models were constructed; both models were filled with crushed, washed and screened 10 to 12 mm diameter river stone. A mixture of primary and secondary effluents from a WWTP was used to test the models, with a chemical oxygen demand of COD &#8776;50 and 100 mg•l-1 respectively. For a uniform 0.5% slope, the maximum flows achieved were 27 and 30 l•min-1 with and without locks. The system worked efficiently breaking the plug flow, mixing the water flow and allowing stable aerobic microbial communities of 5.58 and 8.86 log UFC•g-1, and COD reductions ranging from 90.27 to 555.2 mg•min-1 depending on the pollutant concentration. Key words: freshwater contaminants, self-purification, alternative technology, microbial communities Water SA Vol.31(1) 2005: 101-106