Lactic Acid Bacteria And Bifidobacteria Current Progress In Advanced Research Pdf
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The purpose of this study was to establish the probiotic potential of lactic acid bacteria LAB starter cultures, Lb.
- Molecular typing tools for identifying and characterizing lactic acid bacteria: a review
- Lactic Acid Bacteria And Bifidobacteria Current Progress
- Lactic acid bacteria
She turned to see what was holding her in place. And from the looks of it, the Soviet authorities in Moscow estimated that they should prepare to receive and process a total of 4 million former Red Army soldiers and civilian deportees.
Consumer interest in healthy lifestyle and health-promoting natural products is a major driving force for the increasing global demand of biofunctional dairy foods. A number of commercial sources sell synthetic formulations of bioactive substances for use as dietary supplements. However, the bioactive-enrichment of health-oriented foods by naturally occurring microorganisms during dairy fermentation is in increased demand. While participating in milk fermentation, lactic acid bacteria can be exploited in situ as microbial sources for naturally enriching dairy products with a broad range of bioactive components that may cover different health aspects. Several of these bioactive metabolites are industrially and economically important, as they are claimed to exert diverse health-promoting activities on the consumer, such as anti-hypertensive, anti-inflammatory, and anti-diabetic, anti-oxidative, immune-modulatory, anti-cholesterolemic, or microbiome modulation.
Molecular typing tools for identifying and characterizing lactic acid bacteria: a review
Elaine E. Vaughan, Hans G. While lactic acid bacteria and bifidobacteria have been scientifically important for over a century, many of these are marketed today as probiotics and have become a valuable and rapidly expanding sector of the food market that is leading functional foods in many countries.
In addition, their use as vectors for delivery of molecules with therapeutic value to the host via the intestinal tract is being studied. This review focuses on molecular approaches for the investigation of the diversity of lactic acid bacteria and bifidobacteria in the human intestine, as well as tracking of probiotic bacteria within this complex ecosystem.
Moreover, methodologies to determine the viability of the lactic acid bacteria and bifidobacteria and molecular approaches to study the mechanisms by which they adapt, establish and interact with the human host via the digestive tract, are described.
Scientific interest in the lactic acid bacteria and bifidobacteria can be traced back over a century to the pioneering activities of Louis Pasteur, Ilya Mechnikov and Henri Tissier.
Pasteur's work at the end of the 19th century illustrated that lactic acid fermentation was due to microorganisms while solving a failed wine production in which lactic acid bacteria replaced the alcohol fermentation of yeast. Mechnikov in fact was most famous for describing phagocytosis, but he proposed the ingestion of lactic acid bacteria in order to promote human health, and essentially founded the probiotic concept in the early days of At the same time, Tissier discovered the bifidobacteria and speculated about their use as infant probiotics.
Probiotics have now been defined as live microorganisms that, when administered in adequate amounts, confer a health benefit on the host . Today, fermented dairy foods supplemented with probiotics have grown into a multi-million Euro business . The human digestive tract harbours a wealth of niches with many microbial ecosystems that vary according to location of the intestinal tract. Many members of the lactic acid bacteria as well as bifidobacteria naturally form part of this dynamic ecosystem.
The main lactic acid bacteria found in the human intestine comprise Lactobacillus and Leuconostoc spp. Apart from being indigenous members of the human gut, lactic acid bacteria are found in a plethora of niches, including plant material, fermented dairy, vegetable and meat products and sour dough breads. Foods fermented by lactic acid bacteria are rendered safe by preservation and have improved textures, flavours and tastes.
Hence, a variety of lactic acid bacteria, notably Lactococcus and Lactobacillus spp. However, many of the lactic acid bacteria that are ingested via consumption of these fermented foods do not survive passage of the human intestinal tract.
Lactococcus lactis cells used as a starter for industrial cheese production, provide the largest load of living consumed lactic acid bacteria. Hence, specific strains of lactic acid bacteria that are used to enrich probiotic foods are chosen for their resistance to passage through the human gastro-intestinal tract. This also holds for bifidobacteria that are used as probiotics but as their primary niche is the digestive tracts of humans and other animals, survival is less of an issue than culturing them in industrial environments.
All lactic acid bacteria that include among others the genera Lactobacillus, Lactococcus, Leuconostoc, Pediococcus and Weisella belong to the phylum of the Firmicutes  , and include a great number of species that is most numerous for the lactobacilli, for which over 80 species are known .
The genus Bifidobacterium belongs to the phylum of the Actinobacteria and, as such, is not closely related to the lactic acid bacteria . Similar to the lactic acid bacteria, bifidobacteria are fermentative and produce several acids including lactate, and are predominantly catalase negative. This is not so surprising considering we have co-evolved together with our intestinal microbes over millions of years, and these have been programmed to manipulate networks of genes [ 12—14 ].
The intestinal microorganisms, collectively called microbiota, consist of at least 10 13 microbes and are dominated by anaerobic bacteria, comprising over a species see [ 14—16 ] for reviews and  for a recent inventory. The digestive tract offers a relatively non-hostile environment and supply of nutrients that is produced and consumed by the host. Studies with germ-free and conventional animals that are colonized by intestinal bacteria have shown that the microbiota contributes to diverse processes including roles in host nutrition, intestinal epithelial development and activity, and fat storage, educates the immune system, and maintains the integrity of the mucosal barrier amongst other functions [ 18—20 ].
Lactic acid bacteria and bifidobacteria, both the commensal or ingested members, play a role in the intestinal niche. The proposed dietary strategies to influence the health and well-being of the host include the consumption of probiotics, but also prebiotics and synbiotics. The combination of a probiotic with a prebiotic to support probiotic viability and activity has been termed a synbiotic. The effectiveness of these strategies to influence the composition and activity of lactic acid bacteria and bifidobacteria as well as their effect on the rest of the intestinal microbiota is of significant interest for scientific and industrial reasons.
Several recent reviews are focusing on detecting and identifying lactic acid bacteria and bifidobacteria in the intestine [ 24—26 ].
Here, a brief overview of the current techniques for diversity analysis of the dominant microbiota is provided together with a concise picture of its microbial composition for recent reviews see [ 15 , 17 , 27 ]. A broad range of molecular techniques has become available for the identification, composition and enumeration of the total bacterial community of the intestinal tract Table 1.
During the last decade, the 16S rRNA gene has revolutionised the manner by which taxonomists classify and identify bacteria. The 16S rRNA gene comprises highly variable to highly conserved regions, and the differences in sequence are used to determine phylogenetic relationships and distinguish bacteria at different levels from species to domain. These databases enable new 16S rRNA sequences to be compared with existing sequences. The sequencing of 16S rRNA gene libraries of human intestinal microbiota, generated by PCR amplification of the 16S rRNA gene of DNA from human faeces and mucosa-associated bacteria, has revealed that the diversity of the intestinal microbiota had been vastly underestimated [ 17 , 28 , 29 ].
In the s and s very thorough composition studies were performed on human faeces . Nevertheless, the challenges of obtaining pure cultures, due to the largely anaerobic nature of this community and designing suitable enrichment strategies to simulate intestinal conditions, needed circumvention. A combination of sequence analysis of 16S rRNA gene libraries [ 17 , 28 , 29 ] and fluorescent in situ hybridization FISH approaches targeting the 16S rRNA [ 31 , 32 ] has shown that the most abundant bacterial groups in the human intestine belong to, in order of numerical importance, the phyla of the Firmicutes including the large class of Clostridia and the lactic acid bacteria , Bacteroidetes, Actinobacteria including Colinsella and Bifidobacterium spp.
This has been indirectly confirmed by recent analysis of the metagenome of bacterial viruses bacteriophages recovered from faecal samples that revealed an abundance of viral sequences with sequence similarity to genomes of bacteriophages specific for gram-positive bacteria . Culture-independent methods have aided in identification and culturing of many novel new intestinal members, some of which are quite numerous in the intestine.
This includes the recently discovered phylum of Verrucobacteria that appears to be represented in the human intestine by a single phylotype of Akkermansia mucinophila , isolated for its capacity to utililize mucin as carbon, energy and nitrogen source [ 16 , 34 ]. The vast majority of diversity studies on intestinal lactobacilli has been performed on the accessible faecal samples from healthy individuals.
Furthermore, characteristically food-associated bacteria such as L. Adult caecal samples contained L. Infant faecal samples showed various species but especially L. These data essentially conform to previous culturing studies with the exception of L. While lactobacilli are considered to be culturable after all, they grow and ferment many foodstuffs , culture-independent 16S rRNA clone libraries generated by Lactobacillus group-specific PCR, indicate the presence of novel, not yet cultured, Lactobacillus species especially within the human intestinal tract  ; see below.
Recently described alternative incubation conditions to culture some intestinal lactic acid bacteria, hitherto uncultured, resulted in more easy selection of potentially food-associated ones, such as L. Diversity studies of lactic acid bacteria in intestinal samples other than faeces have been obtained from biopsies following endoscopy of patients, samples from sudden death victims, or capsules that upon swallowing open and sample the intestinal contents.
The predominance of culturable lactobacilli and streptococci in the stomach and especially the small intestine has been reported in many reviews [ 30 , 38 , 40 , 41 ].
However, close inspection of the original data reveals that this abundance of lactobacilli is highly variable between individuals while verification of the isolated lactobacilli has not, or only to a very limited extent, been performed [ 38 , 42 , 43 ]. Hence, the vertical distribution of lactobacilli and other microbial communities in the human intestine needs to be readdressed using modern and molecular approaches.
A recent molecular study on three subjects indicated the relative predominance of lactobacilli for the stomach and the upper segment of the duodenum in two of the subjects Zoetendal, E. Presumably the subject, precise region of the small intestine, and manner of sampling biopsy versus ingesta will influence the numbers of lactobacilli in the small intestine relative to other groups such as Bacteroides and Bifidobacterium spp.
In contrast to lactobacilli, data on bifidobacteria are lacking from the classical studies since the appropriate selective media had not yet been developed. However, bifidobacteria can be an abundant group in the caecum, colon and faecal samples as will be discussed below.
Presently, approximately 20 dominant phylogenetic groups in the human microbiota can be enumerated by a comprehensive set of probes using FISH of the 16S rRNA gene [ 31 , 32 ]. FISH involves whole cell hybridisation with fluorescent oligonucleotide probes targeted against specific bacterial groups and species see Table 1. Studies with these probes are beginning to reveal some trends in typical microbiota composition of infants, adults and elderly.
Application of this probe to faecal samples and comparison to culturing results indicated that bifidobacteria in faeces were for the most part culturable, thus supporting the predominant status of the bifidobacteria within the human intestine . However, since the total culturable counts were only a fraction of the total microscopic counts, the contribution of bifidobacteria to the total intestinal microflora had been over-estimated by almost fold.
Today, following extensive studies in faeces of the north European adult population, bifidobacteria are estimated to comprise 4. In the majority of infants, bifidobacteria become dominant during the first weeks of life. Some infants have no detectable bifidobacteria, as determined by both molecular and culturing studies, and this does not appear to impact on their health [ 37 , 46 ].
Molecular identification of tentative bifidobacterial colonies on various selective media showed that the traditional media were insufficiently selective and unsuitable for quantitative analyses.
The diversity studies have stimulated the development of infant formulas enriched with specific prebiotic oligosaccharides that are bifidogenic, i. Use of the present infant formulas results in a similar abundance of bifidobacteria in faecal samples as is found in the faeces of human milk-fed babies .
Likewise, synbiotic formulations are being designed that increase bifidobacteria in the elderly, who show a marked reduction in bifidobacteria [ 48 , 49 ]. The design of a Lactobacillus -specific FISH probe appeared to be a challenge due to the non-monophyletic nature of this group. The developed LAB probe was found to hybridize to lactobacilli and enterococci, and effective detection often requires permeabilization of the cells prior to hybridisation .
The northern European mean for adults is 1. Many laboratories still use this approach since it is reliable, has been automated, and can be outsourced. More recent studies focus on optimisation of the procedures. The FISH technique is currently the most advanced technique for enumeration of faecal microbiota, in terms of the numbers of probes available and speed of analysis.
It is of course dependent on the availability of the 16S rRNA gene sequence in the databases, and effective probe design and validation Table 1. Enumeration of the major faecal groups as well as bifidobacteria and lactobacilli during a clinical trial to study the efficiency of consumed probiotics to maintain ulcerative colitis patients in remission was recently achieved with FISH-FCM .
Analysis of 16S rRNA gene PCR products by denaturing gradient gel electrophoresis DGGE , a semi-quantitative fingerprinting technique adapted for faecal samples has been widely used to rapidly monitor the microbiota community shifts and compare the communities between different persons, different intestinal locations and due to diets Table 1. Statistical software enables the calculation of similarity indices and cluster analysis to compare the samples. Bands originating from bifidobacteria may often be visualised on DGGE gels since bifidobacteria are usually dominant in humans.
The appearance of bifidobacteria in infant faeces within the first days of life, and their reduction in numbers due to withdrawal of milk following weaning, has been visualised clearly using DGGE profiles of the total microbial community .
Comparison of DGGE profiles of specifically bifidobacterial strains has suggested their vertical transmission from parents to offspring  , confirming earlier studies that were based on a culturing approach and diagnostic PCR on colony DNA . Similarly, this approach been used to characterise the mucosa-associated lactobacilli populations along the human colon .
These were found to be similar to the faecal populations, and not significantly different between healthy persons and those with ulcerative colitis . Remarkably, in the latter study bands originating from L.
The possibility to identify the bands observed in the DGGE gels is a strong advantage of this method. Further studies with specific DGGE profiles showed a rather simple population for bifidobacteria along the colonic mucosa, while the lactobacilli profiles were complex and varied with host and sampling location . Another community fingerprinting technique, terminal restriction fragment length polymorphism T-RFLP , has been adapted for characterising the human faecal bifidobacteria, as well as the tracking of probiotic Lactobacillus strains in intestinal samples [ 62—64 ] Table 1.
A novel phylogenetic assignment database for the T-RFLP analysis of human faecal microbiota PAD-HCM has been designed, which enables the prediction of the terminal-restriction fragments at the species level . This research will facilitate and enhance the use of this technique in studies of dietary and probiotic effects on the microbiota.
Besides the fingerprinting techniques, a whole range of specific 16S rRNA primers has been designed and applied for identification and distribution of bifidobacterial species in human intestinal samples, which are described in recent reviews [ 27 , 65 ]. More recently, real-time quantitative PCR of the 16S rRNA gene is being developed for the detection and quantification of human intestinal bifidobacteria which has the advantages of being high throughput and measuring very low levels of bifidobacteria [ 48 , 65 , 66 ] Table 1.
Numerous real-time PCR based assays are being developed for the major groups within the faecal microbiota of humans, as well as lactobacilli and Bifidobacterium species [ 67—69 ].
These are been used for various applications such as comparison of healthy persons versus patients suffering irritable bowel syndrome . Besides real-time PCR of the 16S rRNA gene, the option to use the transaldolase gene of Bifidobacterium species has also been investigated and appeared to be superior to the former in quantifying bifidobacterial populations in infants .
Lactic Acid Bacteria And Bifidobacteria Current Progress
Six lactic acid bacteria LAB , isolated from the intestinal tract of the longevous population, were prominent for their strong bacteriostatic ability. In this study, the adhesion properties of the six strains were determined in vitro to explore their potential to be used as probiotics. The hydrophobicity and aggregation activity were firstly detected and were varied from Moreover, the adhesion activity to the intestinal crypt cells IEC-6 cells was proved to be varied from 5. Meanwhile every sample was inclined to exclude rather than displace or compete to inhibit the indicator microorganisms to adhere to IEC-6 cells.
Request PDF | On Aug 1, , H. B. Ghoddusi published Lactic Acid Bacteria and Bifidobacteria: Current Progress in Advanced Research.
Lactic Acid Bacteria pp Cite as. Lactic acid bacteria LAB is a general term for a class of bacteria that use the metabolism of carbohydrates in the external environment to produce lactic acid. Lactic acid bacteria are widely distributed in nature and exist in a variety of habitats.
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Lactic acid bacteria
Identification and classification of beneficial microbes is of the highest significance in food science and related industries. Conventional phenotypic approaches pose many challenges, and they may misidentify a target, limiting their use. Genotyping tools show comparatively better prospects, and they are widely used for distinguishing microorganisms. The techniques already employed in genotyping of lactic acid bacteria LAB are slightly different from one another, and each tool has its own advantages and disadvantages.
Lactobacillales are an order of gram-positive , low-GC , acid-tolerant, generally nonsporulating, nonrespiring , either rod-shaped bacilli or spherical cocci bacteria that share common metabolic and physiological characteristics. These bacteria, usually found in decomposing plants and milk products, produce lactic acid as the major metabolic end product of carbohydrate fermentation , giving them the common name lactic acid bacteria LAB. Production of lactic acid has linked LAB with food fermentations , as acidification inhibits the growth of spoilage agents. Proteinaceous bacteriocins are produced by several LAB strains and provide an additional hurdle for spoilage and pathogenic microorganisms. Furthermore, lactic acid and other metabolic products contribute to the organoleptic and textural profile of a food item.
They have generated many tables that will be very useful to researchers in the fıeld. Lactic acid bacteria and bifidobacteria: current progress in advanced.
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