Top PDF Probiotic properties of endemic strains of lactic acid bacteria

Strains of lactic acid bacteria (LAB) isolated from various samples of matsun, yogurt and salted cheese from natural farms of Armenia were studied. They have high antimicrobial and probiotic activities, growth rate and differ by their resistance to enzymes . Supernatants of LAB retain bactericidal activity at р 3.0- 8.0 and inhibit growth of various microflora. The application of different methods of identification and LAB genotyping (API 50 CH, 16S rRNA sequencing, GS-PCR, RAPD PCR) showed that isolated LAB evidenced a 99.9% similarity with L. rhamnosus, L. plantarum and L. pentosus species and coccoid forms of Streptococcus and Enterococcus species. It can be concluded, that some strains of lactic acid bacteria, isolated from dairy products from natural farms of Armenia, can be properly used for biopreservation of some foodstuffs. On the basis of experimental data, the LAB can be used as basis for obtaining the new products of functional nutrition.

This study aimed to isolate native lactic acid bacteria of yellow tail lambari (Astyanax bimaculatus) and evaluate their effect on host microbiota and gut morphology, as well as survival after experimental challenge. The isolated bacterial strains were evaluated for their inhibition against pathogenic bacterial strains in vitro, and the strain with highest inhibitory ability was molecularly identified as Lactobacillus spp. For in vivo testing, eighty fish were distributed in ten tanks equipped with a recirculation system. The experimental units were divided into two treatments: fish fed with Lactobacillus spp. supplement and fish fed an unsupplemented diet (control). After 30 days, guts from three fish from each experimental unit were pooled for microbiological and histological analysis. The other five fish were inoculated with 2.1x10 4 CFU.mL -1 of Aeromonas hydrophila to evaluate survival after 24h. Lambaris fed with the

One approach that led to the reduction and, in a number of cases, the elimination of intestinal pathogenic bacteria in humans and animals includes the ingestion of probiotics in the diary diet (Guarner & Schaafsma 1998, Gopal et al. 2001). Probiotics are live microorganisms that, when ad- ministered in adequate amounts, confer beneficial effects on the host by altering indigenous microbiota and pre- venting infections (FAO/WHO 2001). Lactic acid bacteria (LAB) with probiotic properties, such as Bifidobacterium spp. and Lactobacillus spp. were used to prevent some in- testinal pathogenic infections and to stimulate the host’s immune system in both humans and animals (Perdigón et al. 1999, Fang et al. 2000, Nakazato et al. 2011). It is well documented that Lactobacillus spp. with probiotic proper- ties prevent the growth and toxin production of bacteria such as Campylobacter jejuni, Listeria monocytogenes, He- licobacter pylori, Salmonella, Shigella and Escherichia coli (Jin et al. 1996, Kalantzopoulos 1997, Servin & Coconnier 2003, Poppi et al. 2008, Scapin et al. 2013).

was heat stable, active across a wide pH range, exhibited a broad spectrum of activity and a bacteriostatic mode of action against L. monocytogenes both in culture media and in model cheeses. The bacteriocin-producer showed relevant probiotic features as good auto-aggregation, co-aggregation ability with L. monocytogenes, relatively hydrophobic and basic cell surface, low tolerance to acidic conditions, but good resistance to pancreatin and bile salts. In addition, the strain was able to reduce the adhesion of L. monocytogenes to Caco-2 and HT-29 cells in competition, displacement, inhibition and invasion experiments. Bacteriocins produced by E. faecalis strains were also characterised (Chapter IV) indicating that the activity of most enterocins were not affected by pH, heating and chemical or surfactant agents. However, E. faecalis strains L3A21M3 and L3A21M8 produced thermolabile enterocins. Maximum enterocin productions were observed during the stationary phase and were enhanced with some medium components. Cell-free supernatants of enterococci strains exhibited a bacteriostatic mode of action against L. monocytogenes. PCR amplification with specific primers indicated that strain L3A21M8 carried the gene encoding cytolysin. Probiotic studies also revealed the ability of strains to form biofilms, high hydrophobic character, and good auto-aggregation and co-aggregation capacity with L. monocytogenes. Acidic pH (2.5), bile and pancreatin concentrations of 0.3% and 0.1% respectively were used as stress conditions. Two strains L3A21M3 and L3B1K3 presented the higher survival rate under these conditions. All strains were able to adhere to all intestinal cells tested (Caco- 2 and HT-29 cells). Moreover, all strains presented a high capacity to interfere with the adhesion and invasion of L. monocytogenes to Caco-2 and HT-29 cells. The enterocin produced by E. faecalis L3B1K3 was partially purified and applied to model cheeses contaminated with L. monocytogenes. The semi-purified enterocin reduced survival of Listeria on fresh cheeses in a dose dependent manner. Furthermore, the highest dose tested (2048 AU/g cheese) was effective to reduce Listeria counts to undetected values throughout storage (6 to 72 h).

In the Serbian meat industry, research was performed in order to eventually introduce the application of semi-purified bacteriocins isolated from Leuconostoc mesenteroides E 131 (44, 45), Ln. mesenteroides IMAU:10231 (46-48). Since technological application of the bacteria of the Leuconostoc strain in the meat industry is limited due to their physio- logical properties (they produce mucus, i.e. exopolysaccharides, acetoin, diacetate, etha- nol, etc), which are not acceptable in this industry from the point of view of quality, the direct application of their isolated and purified bacteriocins was a good solution. Unlike them, the bacteriocin-producing strains of Lb. sakei can be added to the meat filling in the form of liquid culture suspensions (49). In addition to protective cultures, the authors ha- ve inoculated into the filling for national fermented sausages (Croatian, Bosnian, Serbian, Greek, Hungarian) the pathogenic L. monocytogenes as well (50). During the ripening process, which lasted 28 days, the reduction of this pathogen was observed. The investi- gation showed a slight antilisterial advantage of Lb. sakei I 151, compared to other two strains that were applied.

Antimicrobial activity of the LAB isolates was investigated against L. innocua 2030c (Central Public Health Laboratory, Colindale, London), a tetracycline- resistant strain. Challenge studies with cold smoked fish have shown that L. innocua 2030c can be considered a suitable marker for replacing L. monocytogenes in experiments where anti-listerial properties of LAB strains are evaluated (Vaz-Velho et al., 2001). An overnight culture (37 1C) of L. innocua 2030c, was diluted in sterile APT broth to an OD (UNICAM 8620, Cambridge, England) between 0.2 and 0.3 (ca.10 6 cfu ml
1 ) before use, and 200 ml were spread on Physico-chemical analyses

Lactobacillus acidophilus and Bifidobacterium animalis subsp. lactis are the lactic acid bacteria that are most frequently used as probiotics. These bacteria grow slowly in milk because they lack essential proteolytic activity and for this reason they are usually combined with Streptococcus thermophilus (Casarotti et al., 2014). Probiotic dairy products should have desired sensorial properties besides the probiotic properties. In order to achieve optimal sensorial properties, mixture of different bacteria can be used. Lactobacillus delbrueckii ssp. bulgaricus are widely used in those combinations due to their acid formation and production of aroma substances such as acetaldehyde. One of the optimal combination of those probiotic bacteria is a culture called ABT which has a combination of L. acidophilus, Bifidobacterium lactis and S. thermophilus. ABY cultures have the the same combination with ABT cultures with an addition of L. bulgaricus and these cultures can be used

Twenty samples of Brazilian meat and meat products were screened by the agar overlay method for bacteriocin- producing lactic acid bacteria, using Lactobacillus sake ATCC 15521 as indicator strain. Based on Gram staining, KOH reaction, catalase test and fermentation of 49 carbohydrates (API 50 CH), three out of seven isolates with confirmed antagonist properties were identified as Lactobacillus curvatus, one as Leuconostoc mesenteroides and one as Leuconostoc sp. Two isolates could not be properly identified using these tests. The inhibitors produced by these strains were sensitive to proteases. Inhibition due to lytic bacteriophages was ruled out, so the isolates were classified as bacteriocin-producing lactic acid bacteria. Four of them presented antilisterial activity and a potential application as biopreservatives in meat systems.

and Madrau et al. (2006) found predominance of the Enterococcus genus in sheep milk and determined their role in proteolysis during cheese maturation. Despite of that, there is not a focus on the probiotic potential of these microorganisms, such as their ability to resist gastric acid and biliary salts in order to reach their final destination  small or large intestine - in viable counts, and their antagonistic potential against important pathogenic microorganisms in the gastrointestinal tract (Silva et al., 2013). It is also important to evaluate antimicrobial susceptibility regarding probiotic properties because of the possible transference of antimicrobial resistance to pathogenic microorganisms from probiotic microorganisms (Lund and Edlund, 2001). Probiotic products are mainly represented by dairy products such as yogurts and fermented milks (Maragkoudakis et al., 2006).

the initial number of contaminant microflora and the temperature of conservation. The risk of a disease burst is also dependent on these variables. The use of GRAS (Generally Regarded as Safe) bioprotective lactic acid microorganisms in meat processing has various purposes (Al-Nabulsi and Holley, 2007), such as safety improvement by inactivation of pathogens (Caplice and Fitzgerald, 1999), pH reduction, thus increasing stability of the product and extending the shelf life by inhibition of undesirable spoilage microorganisms (Cocolin et al., 2004). Lactic acid starters provide diversity in products by modification of raw materials, resulting in new sensorial properties and production of health benefits by the probiotic effects associated to their presence (Lücke, 2000). Microbial growth evolution in food has been studied based on statistical models and laws of probability (Koutsoumanis and Sofos, 2005; Baranyi and Roberts, 1994), under different physical and chemical conditions, as temperature, A w , pH, and type of culture, among others.

A total of ten lactic acid bacterial strains were isolated from the digestive tract of marine shrimp, of which three were biochemically identified as Lactobacillus plantarum, three as L. brevis, two as Weissella confusa, one as Lactococcus lactis, and one as L. delbrueckii. The strain L. plantarum 1 was identified molecularly and kept at the microorganism collection of Centro Pluridisciplinar de Pesquisas Químicas, Biológicas e Agrícolas (CPQBA) of Universidade Estadual de Campinas (Unicamp), under access number CPQBA 007‑07 DRM01. To develop an efficient probiotic for use in aquaculture, it is essential that the microorganism used as a probiotic come from the animal of interest (Balcázar et al., 2006). The results obtained in the present work show that lactic acid bacteria fulfill this requirement.

The interpretation of the fermentation profiles (Table 2) was facilitated by the use of the data base “API-WEB” (BioMérieux) in which the identification of an organism is accompanied by the following information: the percentage of identification (% id), that is, an estimate of how closely the profile corresponds to the stated taxon relative to all the other taxa in the data base. The results of the phenotypic characterization suggests the L. plantarum reference strain and the strains AJ2, AD3, AN3 and AM2 as L. plantarum with % id ≥ 96.7; the strain AL2 as L. plantarum with 72% and as L. pentosus with 27.3%; the strains AF5, C5 and AP3 as Pediococcus pentosaceus with % id ≥ 96.5. For the R2 strains, a clear species or subspecies assignment was not possible because of the doubtful profile of sugar fermentation, evidenced by the % id for L. plantarum and L. pentosus. The strain AB4 presented doubtful phenotypic characterization as L. pentosus and Lactococcus lactis ssp lactis. PCR analysis using species-specific primers for L. plantarum were carried out for the ten isolated strains. Using 16/Lpl primers, the L. plantarum type strain and seven isolated strains (AJ2, AL2, R2, AF5, AD3, AN3 and AM2) gave a PCR product of approximately 220 bp (Fig. 1), as reported by Berthier & Ehrlich (5). Using LbP11/LbP12 primers, the L. plantarum type strain and the same seven isolated strains gave a PCR product of 250 bp (Fig. 2), as reported by Quere et al. (18). Using species-specific primers for L. pentosus 16/Lpe, amplification was observed only for L. pentosus type strain, isolated strains did not give any amplification (data not shown). According to Berthier and Ehrlich (5), the 16/Lpl and 16/Lpe primers allow distinguishing the closely related species L. plantarum and L. pentosus. These primers are complementary to variable sequences in the 16S/ 23S DNA spacer regions of L. plantarum and L. pentosus.

the following composition: lean beef, 25.8%; lean pork, 30.7%; lard, 15.0%; spices and additives, 1.0%; sodium chloride, 2.0% and water, 25.5%. Spices and additives were used as a commercial mixture (Sausage Mixture 314, Kienast & Kratschmer, Kraki, Brazil) composed by sodium tripolyphosphate, sodium polyphosphate, sodium erythorbate, nitrite, nitrate, monosodium glutamate, natural spices and flavorings. The raw ground lean beef and fat were obtained in a local market and stored at -18 ºC in a plastic bag. Ingredients were mixed (STEPHAN/GEIGER, UMMSK–25/40E) and during operation the temperature of the emulsion was maintained below 16 ºC by addition of crushed ice. The emulsion was stuffed into the pre-treated natural casings using a manual stuffer (MADO, MWF 591). The sausages were heat processed at 60 ºC for 2 h and then cooked in steam bath for 15 min after the internal temperature reached 74 ºC. After cooking, the sausages were maintained in a cooling chamber for 24 h, and then vacuum packed in bags (CRYOVAC Sealed Air Corporation) and stored at 4 ºC or 10 ºC for 56 days.

Duration of the lag phase and maximum specific growth rate are strongly influenced by temperature of incubation (Table 1 and Figure 1). With decreasing temperature, there is an increase of lag phase only for L. plantarum. The other two bacteria did not show adaptation phase in any of the tested temperatures. There was a decrease in the maximum specific growth rate with the decrease in the incubation temperature. This trend was observed by other authors, who also found that growth parameters of LAB are influenced by varying the growth temperature 1,2,21 .

Lactic beverages containing probiotics were prepared with whole UHT milk, whey of Mozzarella cheese, soybean hydrosoluble extract and sugar. Three formulations were studied, each one containing a different combination of probiotic/starter bacteria, fermented at two different temperatures (37 and 45 °C). The aim of this work was to verify the influence of these variables on the viability of probiotic microorganisms and on the physicochemical stability of lactic beverages during storage under refrigeration (21 days at 7 °C). The results indicated that the fermentation temperature had a significant effect on the viability of probiotic bacteria. Counts for Lactobacillus acidophilus were affected by storage time, resulting appropriate after 21 days only for the beverage fermented at 37 °C. Physicochemical parameters did not exhibit drastic variations - proving the stability of formulations during storage. Cells of Bifidobacterium spp. showed high survival ability, probably due to the presence of growth promoters from soybean and cheese whey. The fermentation temperature of 37 °C allowed counts above the minimum limit for all the studied microorganisms, being preferred to the temperature of 45 °C. The inclusion of soybean hydrosoluble extract, a prebiotics source, resulted in a symbiotic product with more benefits to the health of consumers.

Essence of modification of silumins boils to change of form or size of silicon crystals present as eutectic or primary ones. Perfect sliding properties and high abrasion resistance of hypereutectoid silumins result from their structure, which can be characterized by precipitations of primary crystals of silicon in soft eutectic groundmass. Primary crystals of silicon are unfavorable due to their impact on machinability of material. They bring about considerable wear of tools and have negative effect on conditions of machined surface (big roughness). In case of hypereutectic silumins, by introduction of active nucleuses of crystallization are refined mainly a brittle, hard precipitations of primary silicon [1]. High content o silicon results in necessity of superheating of the alloy in limits of 850 – 900 C and keeping it

or prolonged storage at ambient conditions, inulin added to a food may be hydrolyzed, which results in the loss of nutritional, physicochemical and functional properties (VORAGEN, 1998; ORAFTI, 1999). Since grain-fermented Kefirs were more acidic during storage (Figure 1 and 2), the hydrolysis of inulin in these formulations was more pronounced. Cardarelli et al. (2008) and Pimentel, Garcia and Prudencio (2012) observed a reduction by 2.7% and 2.4% in inulin content in probiotic petit-suisse cheese and yoghurt, respectively, both stored for 28 days. Furthermore, according to Cruz-Guerrero  et  al. (2006), some strains of Kluyveromyces can produce inulinase; and Atputharajah, Widanapathirana and Samarajeewa (1986) suggested that some yeasts (e.g Candida tropicalis) are able to assimilate inulin. Therefore, it can be said that inulin could have been partially hydrolyzed by yeasts, mainly in the Kefir formulations fermented with grains during the storage time.

The Lactobacillus acidophilus group is a phylogenetically distinct group of closely related lactobacilli. Members of this group are considered to have probiotic properties and occupy different environmental niches. Bacteria generally sense and respond to environmental changes through two component systems (TCSs) which consist of a histidine protein kinase (HPK) and its cognate response regulator (RR). With the use of in silico techniques, the five completely sequenced L. acidophilus group genomes were scanned in order to predict TCSs. Five to nine putative TCSs encoding genes were detected in individual genomes of the L. acidophilus group. The L. acidophilus group HPKs and RRs were classified into subfamilies using the Grebe and Stock classification method. Putative TCSs were analyzed with respect to conserved domains to predict biological functions. Putative biological functions were predicted for the L. acidophilus group HPKs and RRs by comparing them with those of other microorganisms. Some of TCSs were putatively involved in a wide variety of functions which are related with probiotic ability, including tolerance to acid and bile, production of antimicrobial peptides, resistibility to the glycopeptide antibiotic vancomycin, and oxidative condition.

The paper presents a statistical assessment of the effect of chemical composition on mechanical properties of hypereutectic AlSi17 silumin, which is expected to act as a counterpart of alloys used by automotive industry and aviation for casting of high-duty engine parts in West European countries and USA. The studies on the choice of chemical composition of silumins were preceded by analysis of the reference literature to state what effect some selected alloying elements and manufacturing technology may have on the mechanical properties (HB, R m and A 5 ) of these alloys. As alloying additives, Cu, Ni and Mg in proper combinations were used. The alloy after

The complex group of organisms involved in sour rot is known to change fruit composition as a result of the production of high levels of a wide range of undesirable metabolites including acetic acid, glycerol, ethyl acetate, ethanol, acetaldehyde, galacturonic acid, and gluconic acid (Marchetti et al., 1984; Zoecklein et al., 2001). Therefore, it would be advisable to select the grapes according to its health status before fermentation. In small wineries it is current practice to separate damaged grapes manually, but in large wineries, this is not feasible. In this case, crop quality may be visually evaluated but automation is an effective alternative using Fourier transform infrared (FTIR) spectroscopy (Eichinger et al., 2004; Gishen et al., 2005; Kupina and Shrikhande, 2003; Patz et al., 2004; Soriano et al., 2007). The FOSS WineScan FTIR spectrometer has been approved for wine analysis since 1996 with ready-to-use must and wine calibrations provided by the manufacturer (Patz et al., 2004). FTIR spectroscopy in the mid-infrared range in combination with partial least squares (PLS) regression is nowadays an established procedure for the multi-component screening in wine analysis and is able to simultaneously determine several common wine analytes in less than 1 min per sample (Arzberger and Lachenmeier, 2008). In particular, this instrument provides several indicators of grape health, including gray rot, sour rot and yeast and lactic acid bacteria activities (FOSS, 2002).