Immobilization of Lactobacillus bulgaricus with gellan gum and its application in continuous fermentation of D-lactic acid from corn straw / 生物工程学报

Biorefinery of chemicals from straw is an effective approach to alleviate the environmental pollution caused by straw burning. In this paper, we prepared gellan gum immobilized Lactobacillus bulgaricus T15 gel beads (LA-GAGR-T15 gel beads), characterized their properties, and established a continuous cell recycle fermentation process for D-lactate (D-LA) production using the LA-GAGR-T15 gel beads. The fracture stress of LA-GAGR-T15 gel beads was (91.68±0.11) kPa, which was 125.12% higher than that of the calcium alginate immobilized T15 gel beads (calcium alginate-T15 gel beads). This indicated that the strength of LA-GAGR-T15 gel beads was stronger, and the strain was less likely to leak out. The average D-LA production was (72.90±2.79) g/L after fermentation for ten recycles (720 h) using LA-GAGR-T15 gel beads as the starting strain and glucose as the substrate, which was 33.85% higher than that of calcium alginate-T15 gel beads and 37.70% higher than that of free T15. Subsequently, glucose was replaced by enzymatically hydrolyzed corn straw and fermented for ten recycles (240 h) using LA-GAGR-T15 gel beads. The yield of D-LA reached (1.74±0.79) g/(L·h), which was much higher than that of using free bacteria. The wear rate of gel beads was less than 5% after ten recycles, which indicated that LA-GAGR is a good carrier for cell immobilization and can be widely used in industrial fermentation. This study provides basic data for the industrial production of D-LA using cell-recycled fermentation, and provides a new way for the biorefinery of D-LA from corn straw.

Evaluation of physicochemical properties and viability of starter culture of liquid cheese whey-based frozen yogurts supplemented with inulin / Avaliação de propriedades físico-químicas e viabilidade de culturas starters de frozen yogurts à base de soro líquido de queijo suplementados com inulina

ABSTRACT: The study aimed to analyze the physicochemical properties and starter culture viability of frozen yogurts produced with liquid cheese whey (LCW) and inulin at different proportions (F0: 66% LCW and 0% inulin; F1: 65% LCW and 1% inulin; F2: 64% LCW and 2% inulin; F3: 62% LCW and 4% inulin). Results demonstrated that the frozen yogurt F3 presented higher total solids and carbohydrates levels. LCW and inulin contributed to the overrun increase (11.8-18.2%) but did not interfere significantly in the retardation of the melting rate and range in the samples' hardness. Over the storage time, formulation F3 showed lower pH and higher titratable acidity. However, from the sixtieth day of storage, the formulations of frozen yogurts varied in the pH and titratable acidity profile associated with the decline in the viability of starter cultures. Even so, the inulin supplementation positively affected the strains' viability during storage. Based on our data, the formulation F3 presented better nutritional value, physicochemical characteristics, and stability over the storage period.

RESUMO: O estudo teve como objetivo analisar as propriedades físico-químicas e a viabilidade das culturas starters de frozen yogurts produzidos com soro líquido de queijo (SLQ) e inulina em diferentes proporções (F0: 66% SLQ e 0% inulina; F1: 65% SLQ e 1 % inulina; F2: 64% SLQ e 2% inulina; F3: 62% SLQ e 4% inulina). Os resultados demonstraram que o frozen yogurt F3 apresentou maiores teores de sólidos totais e carboidratos. SLQ e inulina contribuíram para o aumento do overrun (11.8-18.2%), mas não interferiram significativamente no retardo da taxa de derretimento e na variação da dureza das amostras. Ao longo do tempo de armazenamento, a formulação F3 apresentou menor pH e maior acidez titulável. Porém, a partir do sexagésimo dia de armazenamento, as formulações de frozen yogurts variaram o perfil de pH e acidez titulável associado ao declínio da viabilidade das culturas starter. Mesmo assim, a suplementação de inulina afetou positivamente a viabilidade das cepas durante o armazenamento. Com base em nossos dados, a formulação F3 apresentou melhor valor nutricional, características físico-químicas e estabilidade ao longo do período de armazenamento.

Effect of cheese containing Lactobacillus delbrueckii subsp. Lactis CRL 581 on blood pressure in prehypertensive and stage 1 hypertensive subjects / Efecto de un queso con LactobacillusdelbrueckiisubspLactis CRL 581 sobre la hipertensión arterial en individuos con prehipertensión o estadio 1 de hipertensión arterial

Hypertension is one of the main risk factors for cardiovascular disease. Functional foods containing bioactive peptides have been proposed as a strategy to decrease blood pressure (BP) in subjects under no pharmacological treatment. The aim of this study was to compare the effect of low-sodium, low-fat (LSLF) cheese and LSLF cheese containing Lactobacillus delbrueckii subsp. lactis CRL 581 (LSLF581) on BP in pre-hypertensive and stage 1 hypertensive subjects. Sixty-one pre-hypertensive and stage 1 hypertensive subjects assigned to one of twos (LSLF, n= 29 and LSLF581, n= 32) participated in this 12-month prospective, randomized, double-blind, crossover trial. Twenty-four h ambulatory BP monitoring was performed at the beginning and at the end of each four-week study period. Systolic and diastolic BP decreased in both study groups, but differences between groups were not significant (systolic, -1.78 and -0.2 mmHg; diastolic, -1.54 and -0.42 mmHg in LSLF581 and LSLF, respectively). Although our results could not support a BP lowering effect of LSLF581, small BP reductions could favorably prevent cardiovascular disease development.

La hipertensión arterial es uno de los principales factores de riesgo de enfermedad cardiovascular. Los alimentos funcionales que contienen biopéptidos constituyen una estrategia útil para disminuir la presión arterial (PA) en personas que no están bajo tratamiento farmacológico. El objetivo del estudio fue comparar el efecto de un queso bajo en sodio y bajo en grasas (BSBG) y el mismo queso con Lactobacillus delbrueckii subsp. lactis CRL 581 (BSBG581) sobre la PA en personas con prehipertensión y estadio 1 de hipertensión arterial. Realizamos un estudio prospectivo, randomizado, cruzado y doble ciego durante 12 meses en 61 personas con prehipertensión y estadio 1 de hipertensión arterial, asignadas a dos grupos: BSBG (n= 29) y BSBG581 (n= 32). Se realizó monitoreo ambulatorio de la PA (MAPA) durante 24 h al comienzo y al final de cada etapa del estudio (cuatro semanas). La PA sistólica y diastólica disminuyó en ambos grupos, aunque las diferencias entre grupos no fueron significativas (sistólica, -1.78 y -0.2 mmHg; diastólica -1.54 y -0.42 mmHg en BSBG581 y BSBG respectivamente). Aunque nuestros resultados no pueden confirmar el efecto hipotensor del queso BSBG581, las reducciones moderadas de la PA podrían prevenir el desarrollo de enfermedad cardiovascular.

Effect of Lactobacillus delbrueckii fermented supernatant on Candida albicans biofilm formation / 中华检验医学杂志

Objective To investigate the effect of Lactobacillus delbrueckii fermented supernatant on Candida albicans biofilm and explore its possible mechanism and effective components.Methods Lactobacillus delbrueckii was isolated from vaginal Lactobacillus capsules (Ding Junsheng) and identified by mass spectrometer and sequencing.Lactobacillus delbrueckii fermented supernatant was prepared.The effect of Lactobacillus delbrueckii fermented supernatant on Candida albicans biofilm was tested by microplate crystal violet staining method and catheterization tube modeling method.Biofilm morphological changes were analyzed by crystal violet staining and Live/ Dead fluorescent dyes.Exopolysaccharides of Candida albicans biofilm was measured by the sulphruic acid-phenol method.The effect of Lactobacillus delbrueckii fermented supernatant on the adherence of Candida albicans biofilm was tested by the method of colony counting on plate.The fermented supernatant was treated with NaOH,catalase,typsin and proteinase K respectively.Then the treated fermented supernatant's effect on Candida albicans biofilm formation was detected.One-way ANOVA or Wilcoxon Rank Sum Test was used as statistical analysis for quantitative data.Results Lactobacillus delbrueckii was successful ly isolated and identified from Ding Junsheng.Lactobacillus delbrueckii fermented supernatant could significantly and dose-dependantly inhibited the formation of Candida albicans biofilm(F=10.804,P=0.000).The morphological changes showed that the fermented supernatant could decrease the formation of biofilm.When treated with Lactobacillus delbrueckii fermented supernatant,Candida albicans biofilm expolysaccharides was significantly inhibited (F=17.140,P=0.000) and adherence ability was reduced.Compared to untreated fermented supernatant (A490=0.486±0.112),the biofilm inhibition effect of fermented supernatant treated with NaOH (A490=0.675 ± 0.095),catalase(A490=0.577 ± 0.118),typsin(A490=0.600 ± 0.044) and proteinase K (A490-0.495±0.084)only decreased slightly,but when compared to the control group (A490=1.079 ± 0.158),the treated fermented supernatant still showed significant biofilm inhibition effect (x2=26.052,P=0.000),which suggested that the effective components of fermented supernatant were organic acid and bacteriocin-like substance.Conclusions Lactobacillus delbrueckii fermented supernatant can effectively inhibit Candida albicans biofilm formation.The action mechanisms are related with expolysaccharides decreasement and adherence reduction.The function components of fermented supernatant are possibly organic acids and bacteriocin-like substance.

Risk Assessment of Lactobacillus delbrueckii subsp. bulgaricus Used as "Other Substances"

The Norwegian Scientific Committee for Food Safety (Vitenskapskomiteen for mattrygghet, VKM) has, at the request of the Norwegian Food Safety Authority (Mattilsynet; NFSA), assessed the risk of "other substances" in food supplements sold in Norway. These risk assessments will provide NFSA with the scientific basis while regulating the addition of “other substances” to food supplements and other foods. "Other substances" are described in the food supplement directive 2002/46/EC as substances other than vitamins or minerals that have a nutritional and/or physiological effect. It is added mainly to food supplements, but also to other foods. VKM has not in this series of risk assessments of "other substances" evaluated any claimed beneficial effects from these substances, only possible adverse effects. The present report is a risk assessment of Lactobacillus delbrueckii subsp. bulgaricus, and it is based on previous risk assessments and articles retrieved from a literature search. The risk of L. delbrueckii subsp. bulgaricus was assessed for the general population. However, in previous assessments of “probiotics” published by VKM, concerns have been identified for specific groups. Therefore, the risk was assessed for the age group with immature gastro-intestinal microbiota (age group 0-36 months), population with mature gastro-intestinal microbiota (>3 years) and vulnerable groups independent of age. VKM has also assessed the risk of L. delbrueckii subsp. bulgaricus in food supplements independent of the dose and have assessed exposure in general terms. Other sources of L. delbrueckii subsp. bulgaricus, such as foods, have not been included in the present risk assessment. VKM concludes that it is unlikely that L. delbrueckii subsp. bulgaricus causes adverse health effects in the general healthy population with mature gastro-intestinal tract. However, no data on long-term adverse effects on infants and young children were identified. As evidence is accruing that the early microbial composition of the neonatal gut is important for the development of the gut microbiota and the immune system of the growing child, it is not possible to exclude that a daily supply of a single particular bacterial strain over a prolonged period of time to an immature gastro-intestinal tract may have long-term, although still unknown, adverse effects on that development.

Producción de ácido láctico a partir del lactosuero utilizando Lactobacillus delbrueckii subsp. bulgaricus y Streptococcus thermophilus / Production of lactic acid from whey using Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus / Produção de ácido láctico de soro de leite coalhado usando Lactobacillus delbrueckii subsp. bulgaricus e Streptococcus thermophilus

El objetivo principal de esta investigación fue determinar las condiciones adecuadas de crecimiento del Lactobacillus delbrueckii subsp. bulgaricus y Streptococcus thermophilus para la producción de ácido láctico, utilizando como sustrato lactosuero proveniente del departamento del Cesar, Colombia. El ácido láctico es producto de la extracción y purificación de caldos de fermentación donde se usa como bacterias fermentativas el co-cultivo Lactobacillus delbrueckii subsp. bulgaricus y Streptococcus thermophilus, usualmente usadas para la producción de yogurt. El sustrato es suplementado con extracto de levadura, fosfato de amonio como fuente de nitrógeno y carbonato de calcio como neutralizante. Esto con el fin de optimizar el consumo, por parte de las bacterias, del carbohidrato principal presente en el suero (lactosa). Durante la fermentación se controló la concentración del inóculo y temperatura, el tiempo máximo fue 72 h. La purificación se llevó a cabo mediante esterificación, filtración de sólidos formados con la reacción y extracción de agua por evaporación y posterior arrastre con nitrógeno. Finalmente se obtuvo ácido láctico con un 78,0% de pureza (36,7 g/L), el cual se caracterizó a través de espectroscopía infrarroja.

O principal objetivo desta pesquisa foi determinar as condições adequadas de crescimento do Lactobacillus delbrueckii subsp. bulgaricus e Streptococcus thermophilus para a produção de ácido láctico utilizando como substrato soro de leite obtido do Departamento do Cesar, Colômbia. O ácido láctico é um produto da extração e purificação de caldos de fermentação, no qual são usadas como bactérias fermentativas Lactobacillus delbrueckiisubsp. bulgaricus e Streptococcus thermophilus, normalmente usadas para a produção de iogurte. O substrato é suplementado com extrato de levedura, fosfato de amonio como fonte de nitrogênio e de carbonato de cálcio como um neutralizador, para optimizar o consumo, pelas bactérias, do principal hidrato de carbono presente no soro (lactose). Durante a fermentação os seguintes fatores foram controlados: concentração do inóculo e temperatura, e atingiu num máximo de 72 h. A purificação foi efetuada por esterificação, filtração dos sólidos formados com a reação e remoção de água por evaporação e varrimento com nitrogênio. Finalmente o ácido láctico foi obtido com 78,0% de pureza (36,7 g/L), e foi caracterizado por espectroscopia de infravermelho.

The main objective of this research was to determine the proper growth conditions of Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus for the production of lactic acid using serum as substract. This serum was obtain from the department of Cesar, Colombia. Lactic acid is the result of the extraction and purification of fermentation broths in which bacteria Lactobacillus delbrueckii subsp bulgaricus and Streptococcus thermophilus are used, which are usually used for the production of yogurt. The substrate was supplemented with yeast extract, ammonium phosphate as a nitrogen source, and calcium carbonate as a neutralizer, in order to optimize the consumption, by the bacteria, of the main carbohydrate present in serum (lactose). During the fermentation (up to 72 h) the inoculums concentration, and temperature were controlled. Purification consisted in esterification, filtration of solids formed during the reaction, and removing of water by evaporation and nitrogen influx. Finally, lactic acid was obtained with 78,0% purity (36.7 g/L), which was characterized by infrared spectroscopy.

Improvement of cell mass production of Lactobacillus delbrueckii sp. bulgaricus WICC-B-02: A newly isolated probiotic strain from mother’s milk.

Lactobacillus delbrueckii sp. bulgaricus WICC-B-02 is new probiotic strain which was initially isolated from the mother’s milk. As lactic acid bacterium, it’s known as a highly efficient probiotic microorganism with a wide range of benefits on the human health. This study was conducted to design and establish industrial platform for high cell mass production of L. delbrueckii sp. bulgaricus for pharmaceutical and food industries application. However, due to low cell mass production caused by the accumulation of lactic acid during the cultivation of lactic acid bacteria, therefore, the optimization of cell mass production with low lactic acid production was developed in this study. The new formulation of the production medium was developed by optimizing the main components such as glucose (30 g.L-1), yeast extract (6.0 g.L-1) and peptone (6.0 g.L-1)in shake flask cultivation. The cell mass production was 3.14 g.L-1, and it increased to 6.08g.L-1 with the lactic acid production being reduced by about 33%, compared to the un-optimized medium.

Mixed Cultures Fermentation for the Production of Poly- ß-hydroxybutyrate

Poly-ß-hydroxybutyrate (PHB) is a biodegradable intracellular microbial product produced by many bacteria and it is comparable to some of the petrochemical derived thermoplastics such as polypropylene. One of the main barriers for the commercial exploitation is the high cost of the substrate for the production of biopolymer. The utilization of mixed microbial cultures facilitates the use of complex substrates thereby reducing the cost of PHB production. In the present study, mixed culture systems were evaluated for PHB production. Bacillus firmus NII 0830 was used for the production of PHB since it accumulates a large amount of PHB and a second organism Lactobacillus delbrueckii NII 0925 was used to provide lactic acid. FTIR and 1H NMR analyses revealed that the PHB extracted from pure culture and mixed culture showed exact match to that of standard PHB. Biodegradation studies of the PHB blends showed 87% degradation. It was also found that a consortium of organisms degraded the films faster than a single organism.

Influence of gastrointestinal system conditions on adhesion of exopolysaccharide-producing Lactobacillus delbrueckii subsp. bulgaricus strains to caco-2 cells

This study aimed to assess the transit tolerance of potential probiotic dairy Lactobacillus strains in human uppergastrointestinal tract in vitro, and to evaluate the effect of EPS production on the viability and adhesion of these strains. Survival and adhesion of two exopolysaccharide (EPS)-producing L. delbrueckii subsp. bulgaricus strains (B3 and B2) and E. coli ATCC11229 were assessed after the exposure of different pH (gastric juice) and gastric plus pancreatic juice challenges. In the artificial gastric juice (pH 2), both the viability of the strain B3 and B2 was decreased. Artificial juice treatments significantly reduced the adhesion to caco-2 cells (P< 0.05). High EPS-producing B3 survived better in the adverse gastrointestinal conditions and showed better ability of adhesion to Caco-2 cells when assessed for competition with E. coli ATCC 11229 compared to low EPS-producing B2. This investigation showed that EPS production could be affected or be involved in the viability, adherence and competition of L. delbrueckii subsp. bulgaricus strains and support the potential of B3 strain for development of new probiotic products.

Influence of different carbon sources on exopolysaccharide production by Lactobacillus delbrueckii subsp. bulgaricus (B3, G12) and Streptococcus thermophilus (W22)

Exopolysaccharides (EPSs) production was studied by Lactobacillus delbrueckii subsp. bulgaricus (B3, G12) and Streptococcus thermophilus (W22) in the medium containing various carbon sources (glucose, fructose, sucrose or lactose). For all the strains, glucose was the most efficient carbon source and B3, G12 and W22 strains produced 211, 175 and 120 EPS mg/L respectively. Also, the influence of different concentrations of glucose (5,10,15,20,25,30 g/L) on EPS production and growth was studied. The results indicated that EPS production and growth were stimulated by the high glucose concentration (30 g/L).