Synergistic effect of green tea extract and probiotics on the pathogenic bacteria, <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> and <Emphasis Type="Italic">Streptococcus pyogenes</Emphasis>

The aim of this study was to assess the effect of a commercial green tea extract (TEAVIGO™) on the microbial growth of three probiotic strains (Lactobacillus and Bifidobacterium), as well as three pathogenic bacteria. MIC and co-culture studies were performed. The MICs of the green tea extract against Staphylococcus aureus and Streptococcus pyogenes (100 μg ml⁻¹) were considerably lower than those against the probiotic strains tested (>800 μg ml⁻¹) and Escherichia coli (800 μg ml⁻¹). In co-culture studies, a synergistic effect of the probiotic strains and the green tea extract was observed against both Staph. aureus and Strep. pyogenes. Green tea extract in combination with probiotics significantly reduced the viable count of both pathogens at 4 h and by 24 h had completely abolished the recovery of viable Staph. aureus and Strep. pyogenes. These reductions were more significant than the reductions induced by probiotics or green tea extracts used separately. These results demonstrate the potential for combined therapy using the green tea extract plus probiotics on microbial infections caused by Staph. aureus and Strep. pyogenes. As probiotics and the green tea extract are derived from natural products, treatment with these agents may represent important adjuncts to, or alternatives to, conventional antibiotic therapy.     

Probiotics from an industrial perspective

Probiotic products have gained popularity with consumers that expect that the products they consume are healthy and help them maintain health. Hence, the need and preferences of the consumers are translated into a product format concept. Probiotics have been used for a long time as natural components in supplements and functional foods, mainly in fermented dairy products. Most of the strains used as probiotics belong to the genera Lactobacillus and Bifidobacterium. By definition, a strain has to have documented health benefits, in order to be called a probiotic. Although each bacterial strain is unique, there are some points that are essential when selecting a probiotic regarding the genetic stability, survival, and technical properties of a strain. Proper components, food matrices and production processes need to be selected since the matrices may affect the viability of the strain in the product and the intestine. Survival in the product is considered a requirement for the beneficial effects of probiotics.     

Recent Advancements in the Development of Modern Probiotics for Restoring Human Gut Microbiome Dysbiosis

A healthy gut is predominantly occupied by bacteria which play a vital role in nutrition and health. Any change in normal gut homeostasis imposes gut dysbiosis. So far, efforts have been made to mitigate the gastrointestinal symptoms using modern day probiotics. The majority of the probiotics strains used currently belong to the genera Lactobacillus, Clostridium, Bifidobacterium and Streptococcus. Recent advancements in culturomics by implementing newer techniques coupled with the use of gnotobiotic animal models provide a subtle ground to develop novel host specific probiotics therapies. In this review article, the recent advances in the development of microbe-based therapies which can now be implemented to treat a wide spectrum of diseases have been discussed. However, these probiotics are not classified as drugs and there is a lack of stringent law enforcement to protect the end users against the pseudo-probiotic products. While modern probiotics hold strong promise for the future, more rigorous regulations are needed to develop genuine probiotic products and characterize novel probiotics using the latest research and technology. This article also highlights the possibility of reducing antibiotic usage by utilizing probiotics developed using the latest concepts of syn and ecobiotics.

     

Probiotic Strains and Their Combination Inhibit <Emphasis Type="Italic">In Vitro</Emphasis> Adhesion of Pathogens to Pig Intestinal Mucosa

The aim of this study was to investigate in vitro the protective effect of commercial probiotic strains (Bifidobacterium lactis Bb12 and Lactobacillus rhamnosus LGG) alone and in combination on the adhesion of pathogenic strains as Salmonella, Clostridium, and Escherichia coli to pig intestinal mucus obtained from different intestinal regions. In combination, probiotic strains enhanced each other’s adhesion, mainly in large intestinal mucus. Treatment of intestinal mucus with Bb12 and LGG, alone or in combination, significantly reduced (P < 0.05) the adhesion of the tested pathogens. The ability to inhibit pathogen adhesion appears to depend on the specific probiotics and pathogens and on the mucosal site. B. lactis Bb12 and L. rhamnosus LGG in combination revealed a better ability to inhibit adhesion of all pathogens tested to pig intestinal mucus than probiotic strains. Probiotic combinations could be useful for counteracting disease-associated aberrations in intestinal microbiota. Specific protective probiotics could be selected for particular pig pathogens. Probiotic strains from human origin and intended for human use also adhere to pig intestinal mucus and are able to displace and inhibit pathogens.     

Antagonistic activity of Lactobacillus acidophilus RY2 isolated from healthy infancy feces on the growth and adhesion characteristics of enteroaggregative Escherichia coli

Enteroaggregative Escherichia coli (EAggEC) infection is an important cause of acute diarrhea, affecting children in developing countries and travelers visiting tropical or subtropical areas. Three probiotics can exert bacteriostatic or bactericidal effects on human and animal intestinal pathogens, the efficiency of probiotics on EAggEC infection remains unclear. In this study, the antagonistic activity of probiotic bacteria isolated from infant faeces was examined against several EAggEC stains. While three isolates, Lactobacillus acidophilus RY2, Lactobacillus salivarius MM1 and Lactobacillus paracasei En4 were shown to significantly inhibit the growth of EAggEC. In addition, the antagonistic activity of the Lactobacillus species was maintained despite heating (100 °C, 15 min) of cell free culture supernatant (CFCS). The antagonistic activity of the CFCS however, could be reduced following lactate dehydrogenase treatment and at pH 7.2. Furthermore, in an adhesion–inhibition assay, L. acidophilus RY2 was shown to be more effective than L. salivarius MM1 and L. paracasei EN4. This study suggests that L. acidophilus RY2 could be used as a probiotic organism against EAggEC.     

Safety and Stability of Two Potentially Probiotic Lactobacillus Strains After In Vitro Gastrointestinal Transit

According to FAO and WHO, probiotics are defined as live microorganisms that, when administered in adequate amounts, confer a health benefit on the host. Most probiotic bacteria used today belong to the genera Lactobacillus and Bifidobacterium and are of animal or human origin. The fundamental characteristic routinely evaluated in potential probiotics strains is their limited viability loss during gastrointestinal transit (GIT), but to date, no studies reported whether probiotics, besides viability, still also maintain their beneficial properties intact. To study this aspect, we considered two strains, Lactobacillus rhamnosus DTA 79 and L. paracasei DTA 83, previously characterised for the presence of some probiotic properties, isolated from faeces of 7- to 21-day-old babies. Here, we examined some additional properties, namely antibiotic resistance, resistance to lysozyme, presence of haemolytic activity and inhibition of pathogen biofilm formation. We then tested the effect of in vitro GIT on all these features and our results show evidence that this procedure had in some cases limited and in others no significant effects on them. Additionally, we examined the gastrointestinal resistance of the strains after skim milk fermentation and successive storage of the product for 20 and 40 days at refrigeration temperature, to see whether prolonged storage could weaken cell resistance to GIT. Our results demonstrate that a protracted refrigeration period before in vitro GIT did not affect or influenced very weakly this essential probiotic property.

     

Comparative Genomics of <Emphasis Type="Italic">Bifidobacterium</Emphasis>, <Emphasis Type="Italic">Lactobacillus</Emphasis> and Related Probiotic Genera

Six bacterial genera containing species commonly used as probiotics for human consumption or starter cultures for food fermentation were compared and contrasted, based on publicly available complete genome sequences. The analysis included 19 Bifidobacterium genomes, 21 Lactobacillus genomes, 4 Lactococcus and 3 Leuconostoc genomes, as well as a selection of Enterococcus (11) and Streptococcus (23) genomes. The latter two genera included genomes from probiotic or commensal as well as pathogenic organisms to investigate if their non-pathogenic members shared more genes with the other probiotic genomes than their pathogenic members. The pan- and core genome of each genus was defined. Pairwise BLASTP genome comparison was performed within and between genera. It turned out that pathogenic Streptococcus and Enterococcus shared more gene families than did the non-pathogenic genomes. In silico multilocus sequence typing was carried out for all genomes per genus, and the variable gene content of genomes was compared within the genera. Informative BLAST Atlases were constructed to visualize genomic variation within genera. The clusters of orthologous groups (COG) classes of all genes in the pan- and core genome of each genus were compared. In addition, it was investigated whether pathogenic genomes contain different COG classes compared to the probiotic or fermentative organisms, again comparing their pan- and core genomes. The obtained results were compared with published data from the literature. This study illustrates how over 80 genomes can be broadly compared using simple bioinformatic tools, leading to both confirmation of known information as well as novel observations.     

马乳酒样乳杆菌马乳酒样亚种及其研究进展

马乳酒样乳杆菌(Lactobacillus kefiranofaciens)是一类革兰氏阳性乳杆菌,其来源广泛,功能多样,安全性好.2020年12月国家卫健委批准马乳酒样乳杆菌马乳酒样亚种作为我国新食品原料.本文主要综述国内外马乳酒样乳杆菌和马乳酒样乳杆菌马乳酒样亚种的菌种形态学和基因组特性、益生功能、主要价值和发展前...     

Effect of non-thermal processing by High Hydrostatic Pressure on the survival of probiotic microorganisms: study on Bifidobacteria spp

High Hydrostatic Pressure (HP) processing has been suggested as an alternative method to improve textural attributes of dairy products. Since, the global market seeks improved functional foods, it is important to investigate whether HP processing can be applied to fermented dairy probiotic products. The inactivation kinetics of Bifidobacterium spp. in a model system of acid pH value under high pressure (100–400 MPa) combined with moderate temperature (20–35 °C) was investigated. Bifidobacterium spp. inactivation followed first order kinetics at all pressure–temperature combinations used. Pressure and temperature were found to act synergistically on the viability loss of the bacterium. The corresponding z_T and z_P values of inactivation were also estimated and, values of 41.5 °C and 93.5 MPa at reference pressure of 200 MPa and reference temperature of 25 °C were estimated, respectively. HP treatment of 200 MPa at 20–25 °C for 10–15 min, recommended for textural modification, is not detrimental to the viability of the studied probiotic culture and would be suitable for respective fermented probiotic products.     

弯曲广布乳杆菌 HFS9 基因组分析及益生特性

【背景】近年来,弯曲广布乳杆菌的健康益处受到广泛关注;基因组分析结合表型实验的方法为益生菌开发提供了新思路。【目的】探索分离自健康人粪便的弯曲广布乳杆菌HFS9基因组特征及益生潜力。【方法】通过泛基因组分析对弯曲广布乳杆菌基因组特征进行描述,基于功能数据库注释并分析HFS9益生相关基因;通过耐酸耐胆盐实验、自聚集、疏水性和细胞黏附实验、抗生素敏感性试验、自由基清除实验及抑菌试验等对HFS9的体外益生特性进行评估;构建小鼠结肠炎模型初步评估HFS9的体内抗炎作用。【结果】弯曲广布乳杆菌具有开放的泛基因组和保守的核心基因组。HFS9基因组大小为1.97 Mb,GC含量为41.86%,蛋白质编码区数目为2 050个;含乳杆菌噬菌体PLE3编码基因及与细胞黏附、酸耐受、胆盐耐受和抗氧化等相关的益生基因。HFS9在酸和胆盐环境中的存活率分别为62.42%和92.92%;自聚集能力和疏水性分别为63.33%和75.00%,对人结肠癌细胞(HT-29细胞)的黏附率为12.97%;对选用的大多数抗生素敏感;对6种常见人体致病菌均具有抑制作用;具有清除1,1-二苯基-2-三硝基苯肼[1,1-diphen...     

Molecular characterization of native isolates of lactic acid bacteria,bifidobacteria and yeasts for beneficial attributes

In a changing scenario of food habits being associated with wellness factors through the concepts of probiotics and prebiotics, an attempt has been made to characterize on molecular basis, the desirable benefits associated with natural isolates of lactic acid bacteria, bifidobacteria, and yeasts. From a diverse range of foods and related samples, based on conventional microbiological protocols, three well-characterized natural isolates of Lactobacillus plantarum MTCC 5422, Bifidobacterium adolescentis MTCC 5423 and Saccharomyces cerevisiae MTCC 5421 were selected. The cultures of L. plantarum and B. adolescentis showed positive polymerase chain reaction (PCR) amplification with oligonucleotide primers targeting genus-specific 16 S rRNA for Lactobacillus and fructose-6-phosphate phosphoketolase for Bifidobacterium. Similarly, species-specific positive amplification in PCR was observed with primers of phytase (acid phosphatase) in S. cerevisiae and α-d-galactosidase and bile salt hydrolase in L. plantarum and B. adolescentis. The cultures of L. plantarum and B. adolescentis exhibited a broad spectrum antibacterial activity against selected foodborne pathogenic bacterial species and tolerance to acid and bile. Gene sequence of respective PCR-amplified products confirmed the genetic identity of the isolated cultures as L. plantarum and B. adolescentis showing 99% homology with the documented sequence of established gene bank.     

Potential probiotic strains with heavy metals and mycotoxins bioremoval capacity for application in foodstuffs

Heavy metals and mycotoxins in foodstuffs are one of the major concerns of our world nowadays. Food decontamination with the help of microbial biomass is a cheap, easy, efficient and green method known as bioremoval. Probiotics are able to reduce the availability of heavy metals and toxins in food products. The purpose of this review is to summarize the probiotics and potential probiotics' interesting role in food bio-decontamination. After a brief glance at the definition of potential probiotic strains with bioremoval ability, LABs (lactic acid bacteria) are described as they are the most important groups of probiotics. After that, the role of the main probiotic and potential probiotic strains (Bacillus, Lactobacillus, Lactococcus, Enterococcus, Bifidobacterium, Pediococcus, Propionibacterium, Streptococcus and Saccharomyces cerevisiae) for heavy metals and mycotoxins bioremoval are described. Additionally, the bioremoval mechanism and the effect of some factors in bioremoval efficiency are explained. Finally, the investigations about probiotic and contaminant stability are mentioned. It is worth mentioning that this review article can be exerted in different food and beverage industries to eliminate the heavy metals and mycotoxins in foodstuffs.     

Evaluation of the Diversity of Probiotic <Emphasis Type="Italic">Bacillus</Emphasis>, <Emphasis Type="Italic">Clostridium</Emphasis>, and <Emphasis Type="Italic">Bifidobacterium</Emphasis> Using the Illumina-Based Sequencing Method

Bacterial species of Bacillus, Lactobacillus, and Bifidobacterium in the intestinal tract have been used as probiotics. Selections for probiotic candidates by the culture-based approaches are time-consuming and labor-consuming. The aim of this study was to develop a new method based on sequencing strategies to select the probiotic Bacillus, Lactobacillus, and Bifidobacterium. The Illumina-based sequencing strategies with different specific primers for Bacillus, Clostridium, and Bifidobacterium were applied to analyze diversity of the genera in goat feces. The average number of different Bacillus, Clostridium, and Bifidobacterium OTUs (operational taxonomic units) at the 97% similarity level ranged from 1922 to 63172. The coverage index values of Bacillus, Clostridium, and Bifidobacterium calculated from the bacterial OTUs were 0.89, 0.99, and 1.00, respectively. The most genera of Bacillus (37.9%), Clostridium (53%), and Bifidobacterium (99%) were detected in goat feces by the Illumina-based sequencing with the specific primers of the genera, respectively. Higher phylogenetic resolutions of the genera in goat feces were successfully established. The results suggest that the selection for probiotic Bacillus, Clostridium, and Bifidobacterium based on the Illumina sequencing with their specific primers is reliable and feasible, and the core Bacillus, Clostridium, and Bifidobacterium species of healthy goats possess the potentials as probiotic microbial consortia.     

Expression of Rice Glutamate Decarboxylase in <Emphasis Type="Italic">Bifidobacterium Longum</Emphasis> Enhances γ-Aminobutyric Acid Production

Bifidobacteria are important for the production of fermented dairy products and probiotic formulas but have a low capacity for γ-aminobutyric acid (GABA) production. To develop a Bifidobacterium strain with an enhanced GABA production, we transformed Bifidobacterium longum with a rice glutamate decarboxylase (OsGADC⁻) gene by electroporation. When the transformed strain was cultured in medium containing monosodium glutamate, the amount of GABA increased significantly compared with those of untransformed Bifidobacterium. Thus, by introducing a plant derived GAD gene, a Bifidobacterium strain has been genetically engineered to produce high levels of GABA from glutamate.     

Immunology and probiotic impact of the newborn and young children intestinal microflora

Human body has developed a holistic defence system, which mission is either to recognize and destroy the aggressive invaders or to evolve mechanisms permitting to minimize or restore the consequences of harmful actions. The host immune system keeps the capital role to preserve the microbial intestinal balance via the barrier effect. Specifically, pathogenic invaders such as, bacteria, parasites, viruses and other xenobiotic invaders are rejected out of the body via barriers formed by the skin, mucosa and intestinal flora. In case physical barriers are breached, the immune system with its many components comes into action in order to fence infection. The intestine itself is considered as an “active organ” due to its abundant bacterial flora and to its large metabolic activity. The variation among different species or even among different strains within a species reflects the complexity of the genetic polymorphism which regulates the immune system functions. Additionally factors such as, gender, particular habits, smoking, alcohol consumption, diet, religion, age, gender, precedent infections and vaccinations must be involved. Hormonal profile and stress seems to be associated to the integrity microbiota and inducing immune system alterations. Which bacterial species are needed for inducing a proper barrier effect is not known, but it is generally accepted that this barrier function can be strongly supported by providing benefic alimentary supplements called functional foods. In this vein it is stressed the fact that early intestinal colonization with organisms such as Lactobacilli and Bifidobacteria and possibly subsequent protection from many different types of diseases. Moreover, this benefic microflora dominated but Bifidobacteria and Lactobacilli support the concept of their ability to modify the gut microbiota by reducing the risk of cancer following their capacity to decrease β-glucoronidase and carcinogen levels. Because of their beneficial roles in the human gastrointestinal tract, LAB are referred to as “probiotics”, and efforts are underway to employ them in modern nutrition habits with so-called functional foods. Members of Lactobacillus and Bifidobacterium genera are normal residents of the microbiota in the human gastrointestinal tract, in which they developed soon after birth. But, whether such probiotic strains derived from the human gut should be commercially employed in the so-called functional foods is a matter of debate between scientists and the industrial world. Within a few hours from birth the newborn develops its normal bacterial flora. Indeed human milk frequently contains low amounts of non-pathogenic bacteria like Streptococcus, Micrococcus, Lactobacillus, Staphylococcus, Corynebacterium and Bifidobacterium. In general, bacteria start to appear in feces within a few hours after birth. Colonization by Bifidobacterium occurs generally within 4 days of life. Claims have been made for positive effects of Bifidobacterium on infant growth and health. The effect of certain bacteria having a benefic action on the intestinal ecosystem is largely discussed during the last years by many authors. Bifidobacterium is reported to be a probiotic bacterium, exercising a beneficial effect on the intestinal flora. An antagonism has been reported between B. bifidum and C. perfringens in the intestine of newborns delivered by cesarian section. The aim of the probiotic approach is to repair the deficiencies in the gut flora and restore the protective effect. However, the possible ways in which the gut microbiota is being influenced by probiotics is yet unknown.     

Inhibitory activity of probiotics <Emphasis Type="Italic">Streptococcus phocae</Emphasis> PI80 and <Emphasis Type="Italic">Enterococcus faecium</Emphasis> MC13 against Vibriosis in shrimp <Emphasis Type="Italic">Penaeus monodon</Emphasis>

Occurrence of widespread epizootics among larval and cultured shrimp has put on viable preventive approaches such as application of probiotics on a high priority in aquaculture. In the present study, four probiotics bacteria were isolated from marine fish and shrimp intestine based on the antagonistic activity and nonpathogenic to the host. The isolates of probiotics strains Streptococcus phocae PI80, Enterococcus faecium MC13, Lactococcus garvieae LC149, B49 and one commercial probiotics (ECOFORCE) were fed to post larvae of Penaeus monodon obtained from two different hatcheries to analyze the growth and protection against Vibrio harveyi and V. parahaemolyticus. Growth of P. monodon post larvae fed with probiotic strain S. phocae PI80 was significantly (P < 0.001) higher when compared with control and other three strains in both experiments. The treatment of post larvae with B49 reduced the growth as well as Specific growth rate. Among the three probiotic strains S. phocae PI80 and E. faecium MC13 have effectively inhibited the pathogens. In experiment I high survival (92%) were observed in S. phocae PI80 treated post larvae when challenged with Vibrio harveyi followed by E. faecium MC13 (84%), B49 (76%) and ECOFORCE (68%) but PI80 did not protect the post larvae in the same experiment when they were exposed to V. parahaemolyticus. The probiotic isolate of MC13 has protected the post larvae against V. parahaemolyticus when compared to other probiotics and control. Similarly in the second experiment feeding of S. phocae enhanced the survival of larvae when challenged with V. harveyi. The laboratory studies proved that bacterial probionts S. phocae and E. faecium isolated from shrimp and brackishwater fish has potential applications for controlling pathogenic vibriosis in shrimp culture.     

Probiotic consortia are not uniformly effective against different amphibian chytrid pathogen isolates

Symbiotic bacterial communities can protect their hosts from infection by pathogens. Treatment of wild individuals with protective bacteria (probiotics) isolated from hosts can combat the spread of emerging infectious diseases. However, it is unclear whether candidate probiotic bacteria can offer consistent protection across multiple isolates of globally distributed pathogens. Here, we use the lethal amphibian fungal pathogen Batrachochytrium dendrobatidis to investigate whether probiotic richness (number of bacteria) or genetic distance among consortia members influences broad‐scale in vitro inhibitory capabilities of probiotics across multiple isolates of the pathogen. We show that inhibition of multiple pathogen isolates by individual bacteria is rare, with no systematic pattern among bacterial genera in ability to inhibit multiple B. dendrobatidis isolates. Bacterial consortia can offer stronger protection against B. dendrobatidis compared to single strains, and this tended to be more pronounced for consortia containing multiple genera compared with those consisting of bacteria from a single genus (i.e., with lower genetic distance), but critically, this effect was not uniform across all B. dendrobatidis isolates. These novel insights have important implications for the effective design of bacterial probiotics to mitigate emerging infectious diseases.     

Exopolysaccharide production of <Emphasis Type="Italic">Lactobacillus salivarius</Emphasis> BCRC 14759 and <Emphasis Type="Italic">Bifidobacterium bifidum</Emphasis> BCRC 14615

In the present study, the production of exopolysaccharides (EPS) by 13 strains of Lactobacillus and 6 strains of Bifidobacterium in a chemical defined medium (CDM) supplemented with 30 g lactose/l was first compared. The highest EPS production of the Lactobacillus strains was found in L. salivarius BCRC 14759 while among the Bifidobacterium strains examined, B. bifidum BCRC 14615 showed the highest EPS production. Analyzes of the effect of lactose concentration and cultivation temperature on EPS production revealed that L. salivarius produced the highest amount of EPS (45.3 mg/l) in CDM supplemented with 5 g lactose/l at 40°C while B. bifidum produced the highest EPS (17.0 mg/l) in CDM supplemented with 40 g lactose/l at 35°C. α-Phosphoglucomutase, UDP-glucose pyrophosphorylase and UDP-galactose-4-epimerase exhibited a markedly notable activity compared with other enzymes examined in the cell extract of both test organisms. This indicates their possible involvement in the biosynthesis of EPS.     

The probiotic properties and potential of vaginal Lactobacillus spp. isolated from healthy women against some vaginal pathogens

During the last decade, probiotic research has progressed considerably and significant advances have been made in the selection and characterization of specific probiotic strains. The most studied probiotics belong to the genus Lactobacillus. In this study, 80 Lactobacillus spp. isolated from healthy women tolerated low pH and were able to grow in the presence of bile salts. RAPD PCR technique resulted in the identification of 38 different types. These isolates were then evaluated based on adhesion capacity, antibiotic susceptibility and tolerance in simulated gastrointestinal tract. Species-specific PCR and detection of bacteriocin-related genes were also surveyed. Among the isolates, five strains—Lacticaseibacillus rhamnosus NO21, Lacticaseibacillus casei NO1, Lactiplantibacillus plantarum NO4, Lactobacillus acidophilus NO7 and Lactobacillus gasseri NO38—presented acceptable antibiotic susceptibility pattern. Further analysis showed antimicrobial activity of Lacticaseibacillus culture against various bacterial pathogens and real-time PCR showed all five strains were able to prevent the colonization of bacterial pathogens. All five selected strains produced organic acids, hydrogen peroxide and were resistant to the spermicide. In addition, they lacked haemolytic activity with the ability of hydrophobicity, auto-aggregation and co-aggregation with pathogens. These results suggest that the vaginal microbiome could be a good source for the isolation of probiotics and the strains of this study may be considered as good probiotic candidates.     

Glucans from fruit bodies of cultivated mushrooms Pleurotus ostreatus and Pleurotus eryngii: Structure and potential prebiotic activity

Cultivated oyster mushrooms (genus Pleurotus) are interesting as a source of biologically active glucans. Partially, β-glucan from Pleurotus sp. (pleuran) has been used as food supplements due to its immunosuppressive activity. Like other dietary fibre components, oyster mushroom polysaccharides can stimulate the growth of colon microorganisms (probiotics), i.e. act as prebiotics. Specific glucans were isolated from stems of Pleurotus ostreatus and Pleurotus eryngii by subsequent boiling water and alkali extraction. Obtained water soluble (L1), alkali soluble (L2) and insoluble (S) fractions were characterised by various analytical methods. Spectroscopic analysis detected glucans in all the fractions: branched 1,3-1,6-β-d-glucan predominated in L1 and S, while linear 1,3-α-d-glucan in L2. Fractions L1 also contained marked amount of proteins partially in complex with glucans; protein content in L2 was insignificant. Effective deproteinisation of L1 and separation of α- and β-glucans in L2 was achieved by the treatment with phenolic reagent. Small amount of chitin was found in S as a component of cell wall chitin–glucan complex. Potential prebiotic activity of extracts L1 and L2 was testing using nine probiotic strains of Lactobacillus, Bifidobacterium and Enterococcus. These probiotics showed different growth characteristics dependently on used extract and strain specificity due to the presence of structurally diverse compounds. The extracts L1 and L2 can be applied to synbiotic construction only for carefully selected probiotic strains. This exploitation of fruit body extracts extends the use of mushrooms P. ostreatus and P. eryngii for human health.