Potential Of Lactic Acid Bacteria Research Articles

Screening for gum-producing Lactic acid bacteria in Oil palm (Elaeis guineensis) and raphia palm (Raphia regalis) sap from South-West Nigeria.

Lactic acid bacteria have wide applications in food processing. Lactic acid bacteria produced exopolysaccharides (EPS) which could be used as possible replacer for commercial stabilizer and thickeners produced by nonfood grade bacteria. Seventy‐two samples of Oil and Raphia palm sap were collected in eighteen locations across South‐Western Nigeria and screened for exopolysaccharide production in 6% sucrose agar using streaked plate method. Four hundred EPS‐producing bacteria (EPB) isolated were clustered based on morphological characteristics into two broad groups and preliminary screened for EPS‐producing capacity. Twenty representative of EPB were selected from the broad groups for tentative identification by API 50CHL and 10 high yielding EPB were selected for large‐scale EPS production. Each strain was inoculated into 6% sucrose broth with 3% (v/v) preculture grown overnight in a 1.5 ml flask and incubated at 37°C for 72 hr. The EPSs were purified and freeze‐dried prior to quantification of yields. EPS‐producing bacteria were identified as Leuconostoc lactis, Lactobacillus fermentum, Lactobacillus delbrueckii ssp. lactis, L. delbrueckii ssp. delbrueckii, Lactobacillus acidophilus, Lactobacillus plantarum, Lactobacillus crispatus, and Leuconostoc mesenteroides ssp. mesenteroides/dextranicum. EPS yield ranged from 132–810.75 mg/L and EPS‐producing potential of lactic acid bacteria (LAB) strains ranged; 36% (132–245 mg/L), 36% (250–460 mg/L), and 28% (461–820 mg/L). L. plantarum had the highest EPS yield of 810.75 mg/L whereas L. crispatus had the least yield 242.5 mg/L. These results suggest that majority of LAB in palm wine saps are gum‐producing bacteria. Leuconostoc and Lactobacillus were the most abundant LAB found in this study while L. plantarum could have applications as potential starter cultures for the production of exopolysaccharides (EPS) at industrial level.

Lactic acid bacteria: from starter cultures to producers of chemicals.

Lactic acid bacteria constitute a diverse group of industrially significant, safe microorganisms that are primarily used as starter cultures and probiotics, and are also being developed as production systems in industrial biotechnology for biocatalysis and transformation of renewable feedstocks to commodity- and high-value chemicals, and health products. Development of strains, which was initially based mainly on natural approaches, is also achieved by metabolic engineering that has been facilitated by the availability of genome sequences and genetic tools for transformation of some of the bacterial strains. The aim of this paper is to provide a brief overview of the potential of lactic acid bacteria as biological catalysts for production of different organic compounds for food and non-food sectors based on their diversity, metabolic- and stress tolerance features, as well as the use of genetic/metabolic engineering tools for enhancing their capabilities.

Antagonistic Activities and Probiotic Potential of Lactic Acid Bacteria Derived From a Plant-Based Fermented Food.

In this study, antagonistic activities and probiotic potential of lactic acid bacteria (LAB) derived from a plant-based fermented food, kimchi, were demonstrated. The cell free supernatants (CFS) from Lactobacillus curvatus KCCM 43119, Leuconostoc mesenteroides KCCM 43060, Weissella cibaria KCTC 3746, and W. koreensis KCCM 41517 completely inhibited the growth of foodborne pathogenic bacteria, while neutralized CFS (pH 6.5) partially inhibited the growth. The competition, exclusion, and displacement of foodborne pathogenic bacteria by the LAB strains from adhesion to HT-29 cells were investigated. The LAB strains were able to compete with, exclude, and displace the foodborne pathogenic bacteria. However, the degree of inhibition due to the adhesion was found to be a LAB strain-dependent phenomenon. The LAB strains showed high coaggregation with foodborne pathogenic bacteria, and they also exhibited high resistance to acidic condition. Except W. cibaria KCTC 3746, all LAB strains were capable of surviving in the presence of bile salts. Furthermore, while all LAB strains were resistant to chloramphenicol, kanamycin, streptomycin, gentamicin, and erythromycin, only W. cibaria KCTC 3746 and W. koreensis KCCM 41517 displayed resistance to vancomycin. These results suggest that the LAB strains derived from kimchi exerted antagonistic activities against foodborne pathogenic bacteria with probiotic potential.

Microbiological analysis and assessment of biotechnological potential of lactic acid bacteria isolated from Tunisian flours

This work was carried out to identify lactic acid bacteria (LAB) from baking wheat flours and to evaluate their technological capabilities for potential incorporation in sourdough process. Six samples of wheat flours obtained from different geographical regions of Tunisia were microbiologically analyzed. Several technological features including acidification, antimicrobial, amylolytic, proteolytic, and antioxidant activities of six selected LAB strains were investigated for future in situ applications. Moreover, LAB were investigated for their ability to produce exopolysaccharides. A total of 45 autochthonous LAB were isolated and identified by genetic analysis of 16S–23S rRNA intergenic transcribed spacer (ITS)-generated patterns ITS-PCR. One of each ITS-PCR pattern was subjected to partial 16S rRNA gene sequencing, and strains were identified as Weissella cibaria, Lactobacillus plantarum, Lactobacillus brevis, Pediococcus pentosaceus, Pediococcus pentoseus, Pediococcus acidilactici, Enterococcus faecium, Enterococcus casseliflavus, and Enterococcus faecalis. All tested LAB showed good acidifying ability by decreasing significantly (p < 0.05) the pH of flour extract below 4.0 after 24 h and below 3.0 after 72 h. Pediococcus pentoseus and P. acidilactici presented fermentation quotient (FQ, ratio of lactic and acetic acids) close to the optimal range. All LAB isolates demonstrated extracellular proteolytic activity. Weissella cibaria S25 had the highest radical-scavenging activity with 25.57%. Lactobacillus plantarum S28 demonstrated the highest amylolytic activity (1386 U/mL) followed by P. acidilactici S16 (1086 U/mL). Although, L. plantarum S28 showed the highest production of exopolysaccharides (0.97 g/L). Moreover, varying halo of inhibition was detected against Escherichia coli, Staphylococcus aureus, Aspergillus niger, and Penicillium expansum. This study revealed that autochthonous flour LAB had interesting technological features and thus could be used in sourdough production.

Potential of lactic acid bacteria to modulate coffee volatiles and effect of glucose supplementation: fermentation of green coffee beans and impact of coffee roasting.

Coffee flavor can be significantly influenced by microbial activities in spontaneous fermentation of coffee cherries. The potential of lactic acid bacteria for flavor modulation through controlled fermentation of green coffee beans has not been explored. Fermentation by Lactobacillus rhamnosus HN001 with and without 1% w/w glucose supplementation led to modification of flavor-related constituents in green coffee beans, which translated into modulation of coffee volatiles upon roasting. The lactic acid bacteria consumed almost all glucose and fructose, leaving sucrose behind. Amino acids and malic, citric, and succinic acids were partially catabolized. Glucose supplementation enhanced lactic acid production but repressed acetic acid formation. After roasting at 235 °C for 9min, 12 min, and 15 min, the levels of furfurals in glucose-supplemented-fermented coffee were 10.5-, 2.7-, and 1.1-fold higher than those in the controls (nonsupplemented-unfermented coffee); furthermore, the levels of pyrazines in the controls were 11.9-, 10.1-, and 6.5-fold higher than those in the treated coffee. Glucose-supplemented fermentation yielded roasted coffee with stronger caramelic and burnt characteristics but weaker nutty notes. In roasted non-supplemented-fermented coffee, volatile production was generally reduced, resulting in a milder overall aroma. Lactic acid fermentation of green coffee beans is a new strategy for coffee flavor modulation, creating novel aroma characteristics. © 2018 Society of Chemical Industry.

In vitro selection of potential immunomodulatory multispecies lactic acid bacteria in broilers

Modulation of host immunity is one of the proposed benefits of the consumption of probiotics.In this study a total of 26 lactic acid bacteria belonging to eight different species were isolated from chicken gut. These twenty six probiotic organisms were characterized by Gram’s staining, biochemical methods using 21 sugars, pH tolerance and bile salt tolerance test. These probiotic organisms were identified using PCR amplification of 16S-23S spacer region and sequencing analysis. Based on the sequencing data, 6 different species were found to exist namely Enterococcus faecalis; Enterococcus faecium, Enterococcus hirae, Weissella cibaria, Lactobacillus salivarius, Pediococcus acidilactici. To select the immunomodulatory probiotic bacteria, the scoring index was established based on different chicken cytokine expression and B and T cell receptor expression studies. According to scoring index, Pediococcus acidilactici, Lactobacillus salivarius and Weissellacibaria showed highest levels of fold increase in the expression of Th1 cytokines viz. IL2, IL 12p40, IL1b and TNF a. Enterococcus faecalis and Enterococcus faecium showed highest levels of fold increase in the expression of Th2 cytokines viz. IL 4, IL10, TGF b and IL6.

ISOLATION AND CHARACTERIZATION OF POTENTIAL PROBIOTICS FROM FERMENTED RAGI (ELEUSINE CORACANA)

Objective: The aim of this study was to isolate, characterize and identify the potential lactic acid bacteria from fermented ragi millet (Eleusine coracana).Methods: A total of 177 isolates were isolated from the fermented ragi porridge. All the isolates were subjected to preliminary screening (Gram staining and catalase test). The physiological features of the probiotic isolates such as tolerance to pH (2.0, 4.0), phenol (0.3%, 0.5%) and bile salt (0.3%) were carried out. Antibiotic susceptibility test was performed using disc diffusion method. Free radical scavenging assay was conducted by 2,2-diphenyl-1-picrylhydrazyl (DPPH) method. The isolates were further characterized for their cholesterol-lowering property. Based on their survival ability and biochemical tests, the selected potent isolates were identified by 16S rRNA gene sequence by PCR and phylogenetic analysis. The 16S rRNA gene sequencing confirmed that isolates were Lactococcus lactis RS01, Lactobacillus plantarum RS09, Lactobacillus plantarum RS16 and Lactobacillus plantarum RS23.Results: Twenty five isolates were screened from the 177 total isolates based on their morphological and biochemical characteristics (Gram staining and catalase test). All the isolates showed tolerance against acid, phenol and bile salts. However, RS09 and RS23 exhibited maximum viable count and demonstrated good tolerance at the end of 3 h. Highest antioxidant activity was recorded in RS09 ranging from 32-85%. Among the tested strains, the degradation rate of supernatants, RS09 (61.9%), RS23 (60%) and RS01 (58.97%) and RS16 (56.2%) showed the highest cholesterol assimilation rate. In addition, they also found to be resistant and sensitive to few antibiotics.Conclusion: Based on the obtained results, these isolates are ideal in vitro probiotic strains and can be used further for in vivo evaluation.

Characterization and screening for probiotic potential of Lactic Acid Bacteria Isolated from Traditionally Fermented Wheat "Hamoum"

The Algerian couscous, "Hamoum”, is prepared from fermented wheat which is the result of wheat grains being stored in an artisanal underground grana-ry called "Matmora" for more than one year. This method of storage has been abandoned in favor of conventional modes without being well studied and known. However, it is used on family scale farms. The purpose of this study was to explore the biodiversity of microbial flora of fermented wheat due to this type of storage. A total of 39 isolates were evaluated in terms to identify lactic acid bacteria and screening the probiotic properties. The phe-notypic results showed a diversity of lactic flora and lactic acid bacteria iso-lated from fermented wheat mainly belonging to Lactobacillus (69%) fol-lowed by Pediococcus (15%), Leuconostoc (8%) and Enterococcus (8%). The genotypic characterization revealed the dominance of Lactobacillus plantarum. The identified strains Lactobacillus plantarum (M6), Lactobacillus plantarum (R27), Lactobacillus brevis (BL8) and Pediococcus acidilactici (M5) have a high antibacterial activity and all strains have resistance to low acidic pH and bile salts. This investigation has enabled a screening of lactic acid bacteria from traditionally fermented wheat. “Hamoum” is a substrate rich in lactic acid bacteria that has exceptional probiotic potential. It’s may be the starting point for further characterization of biotechnological properties in order to identify and select probiotic strains for therapeutic purposes.

Evaluation of Probiotic Potential of Lactic Acid Bacteria Isolated from Different Sources in Western India

ABSTRACTLactic acid bacteria isolated from unconventional sources are often attractive targets in the quest for obtaining better probiotics. In the present study, 16 members of the genus Lactobacillus, isolated from 3 different sources in western India, viz., plants, fermented foods and beverages, and human feces, were evaluated for their probiotic and bioactive properties. The isolates were closely related to Lactobacillus fermentum, Lactobacillus pentosus, and mainly Lactobacillus plantarum. The isolates were tolerant to bile salt, acidic pH and pancreatin, although pancreatin tolerance was generally low. Cellular extracts of several isolates displayed antioxidant activity, while cell-free supernatants displayed antibacterial activity against human pathogens. Antioxidant activity of Lactobacilli of human origin was higher than those from vegetables or fermented foods and beverages. L. plantarum AG40V prevented spoilage of fresh-cut fruits, vegetables and sprouted mung-beans. Lactobacilli from all sources displayed equal probiotic potential and those of human origin displayed superior antioxidant activity over others.

The antagonistic activity of lactic acid bacteria isolated from peda, an Indonesian traditional fermented fish

Peda is an Indonesian traditional fermented whole fish prepared by addition of salt prior to fermentation and drying process. Salt used to control the growth of the lactic acid bacteria for the fermentation process. The objectives of this study were isolating and characterize the potential lactic acid bacteria (LAB) from peda as culture starter candidate, particularly its activity against pathogenic bacteria. A total of five samples from five regions of East Java Province was collected and subjected to LAB isolation. Fifty-seven of 108 colonies that show clear zone in de Man, Rogosa and Sharpe (MRS) agar supplemented with 0.5% CaCO3 were identified as LAB. Twenty-seven of the LAB isolates were exhibit inhibition against Staphylococcus aureus ATCC 6538 and Pseudomonas aeruginosa ATCC 27853. Isolate Aerococcus NJ-20 was exhibited strong inhibition against S. aureus ATCC 6538 (7.6 ± 1.35 mm inhibition zone) but was not produce bacteriocin. This finding suggests that the isolate Aerococcus NJ-20 can be applied as biopreservative culture starter on peda production. Further analysis on technological properties of isolates will be needed prior to application.

Characterization and probiotic potentials of lactic acid bacteria isolated from ingesta of selected ruminants

Studies were carried out to isolate and screen lactic acid bacteria with probiotic potentials and amylolytic activities from the ruminal ingesta of cow and goat. Ninety isolates obtained from the three abattoirs were divided into the following species: Lactobacillus plantarum, L. fermentum, L. pentosus, L. brevis, L. buchneri, L. collinoides, and Leuconostoc mesenteroides. The isolates were screened for probiotic potentials and amylolytic activities. Four isolates possessed probiotic potentials: L. plantarum CA3b, L. fermentum GA2d, L. plantarum GA1d, and L. plantarum GA3e. Lactobacillus plantarum CA3b, L. fermentum GA2d, and L. plantarum GA3e survived pH 2.5 and 3.5 after 180 min. Lactobacillus plantarum GA1d had the highest tolerance of 82.44% and 71.03% to 0.3% and 1% bile salts concentrations, respectively. Lactobacillus plantarum CA3b hydrolysed 3% starch with an average zone of clearance of 10.0 mm, while L. plantarum GA1d hydrolysed 2% with a zone of 9.5 mm. These two strains also possessed bacteriocin activities against E. coli, and were characterised based on their reactions to pH, temperature, and enzymes treatments. Ruminal ingesta of cow and goat harbour lactic acid bacteria possessing amylolytic and probiotic potentials, which can be exploited in the fermentation of feedstock, conferring health benefits and improved performance to these ruminants.

In Vitro Evaluation of Probiotic Potential of Lactic Acid Bacteria Isolated from Yunnan De'ang Pickled Tea.

This study aimed to investigate the probiotic potential of lactic acid bacteria (LAB) strains isolated from De'ang pickled tea, a traditional food consumed by the De'ang nationality of Yunnan, China. Twenty-six LAB strains isolated from De'ang pickled tea were subjected to identification based on 16S rRNA gene sequence analysis. Twenty-four belonged to Lactobacillus plantarum, one belonged to Enterococcus casseliflavus, and one belonged to Lactobacillus acidophilus. Eighteen out of 26 LAB strains which showed a higher capability to tolerate simulated gastrointestinal juices were chosen to further evaluate their probiotic properties. Varied adhesive abilities and auto-aggregative capacities of selected LAB strains were dependent on species and even strains. All tested LAB strains were resistant to kanamycin, streptomycin, gentamycin, and vancomycin and sensitive to tetracycline and chloramphenicol. Ten out of the 18 strains are resistant to ampicillin, and the remaining strains are sensitive to ampicillin; 4 out of the 18 strains showed resistance to erythromycin. Compared to reference strain Lactobacillus rhamnosus strain GG, these LAB strains had a greater or comparative antimicrobial activity against Salmonella typhimurium or Escherichia coli. In contrast, eight out of the 18 strains suppressed growth of Shigella flexneri. Two L. plantarum strains, ST and STDA10, not only exhibited good probiotic properties but also showed a good ability of scavenging DPPH and ABTS+. This study suggests that L. plantarum ST and STDA10 could be used as potential probiotics applied in functional foods.

Staphylococcus aureus undergoes major transcriptional reorganization during growth with Enterococcus faecalis in milk

Previous studies have demonstrated the antagonistic potential of lactic acid bacteria (LAB) present in raw milk microbiota over Staphylococcus aureus, albeit the molecular mechanisms underlying this inhibitory effect are not fully understood. In this study, we compared the behavior of S. aureus ATCC 29213 alone and in the presence of a cheese-isolated LAB strain, Enterococcus faecalis 41FL1 in skimmed milk at 30 °C for 24 h using phenotypical and molecular approaches. Phenotypic analysis showed the absence of classical staphylococcal enterotoxins in co-culture with a 1.2-log decrease in S. aureus final population compared to single culture. Transcriptional activity of several exotoxins and global regulators, including agr, was negatively impacted in co-culture, contrasting with the accumulation of transcripts coding for surface proteins. After 24 h, the number of transcripts coding for several metabolite responsive elements, as well as enzymes involved in glycolysis and acetoin metabolism was increased in co-culture. The present study discusses the complexity of the transcriptomic mechanisms possibly leading to S. aureus attenuated virulence in the presence of E. faecalis and provides insights into this interspecies interaction in a simulated food context.

Probiotic Potential of Lactic Acid Bacteria from Yellow Bamboo Shoot Fermentation using 2.5% and 5% Brine at Room Temperature

Yellow bamboo shoot is a popular food material especially in Semarang because it is used as filling for lumpia (authentic food of Semarang). Beside used as filling, yellow bamboo shoot commonly known by Indonesian people. Considering bamboo shoot often processed into fermented traditional food, yellow bamboo shoot also potential to be examined as source of fermented food producing lactic acid bacteria. Lactic acid bacteria still become the most beneficial microorganisms associated with gastrointestinal system and moreover for obesity diet. The aim of this research is to study the probiotic potential of lactic acid bacteria produced from yellow bamboo shoot fermentation in 2.5% and 5% brine under room temperature (30 °C). From isolation, 22 single colonies obtained from 2.5% brine and 27 isolates obtained from 5% brine. The morphology and physiology analysis resulted in Lactobacillus and Streptococcus genus. All isolates were tested subsequently for probiotic potential. Based on the result, more than 50% identified isolates have probiotic potential.

Isolation and evaluation of probiotic potential of lactic acid bacteria isolated from poultry intestine

The gut is a source of lactic acid bacteria with remarkable functional and technologies properties as well as a potential source of probiotics. In the present study, 13 strains of Lactobacillus were isolated from poultry intestine and identified according to their 16S rDNA sequences, as well as the evaluation of their probiotic potential. The probiotic properties were tested in aspects of antibiotic susceptibility, antimicrobial activity, exopolysaccharide production, lysozyme tolerance, gut condition tolerance (low pH, bile salt tolerance) and adhesion to human colorectal adenocarcinoma cell line (Caco-2). Most isolates were resistance to streptomycin (10 μg/mL), gentamicin (10 μg/mL), kanamycin (30 μg/mL), penicillin (10 μg/mL) and chloramphenicol (30 μg/mL). Isolates shows strong abilities to adhere to Caco-2 cell in the range of (76 to 85%). Isolates SHA101 to SHA113 showed high survival rate under gastrointestinal tract condition (>80%), indicating their potential in application of probiotics. The results of these tests indicate that the lactic acid bacteria isolated from poultry intestine have potential use as probiotic in various products.

Isolation, Molecular Characterization and Probiotic Potential of Lactic Acid Bacteria in Saudi Raw and Fermented Milk.

Probiotic bacteria can confer health benefits to the human gastrointestinal tract. Lactic acid bacteria (LAB) are candidate probiotic bacteria that are widely distributed in nature and can be used in the food industry. The objective of this study is to isolate and characterize LAB present in raw and fermented milk in Saudi Arabia. Ninety-three suspected LAB were isolated from thirteen different types of raw and fermented milk from indigenous animals in Saudi Arabia. The identification of forty-six selected LAB strains and their genetic relatedness was performed based on 16S rDNA gene sequence comparisons. None of the strains exhibited resistance to clinically relevant antibiotics or had any undesirable hemolytic activity, but they differed in their other probiotic characteristics, that is, tolerance to acidic pH, resistance to bile, and antibacterial activity. In conclusion, the isolates Lactobacillus casei MSJ1, Lactobacillus casei Dwan5, Lactobacillus plantarum EyLan2, and Enterococcus faecium Gail-BawZir8 are most likely the best with probiotic potentials. We speculate that studying the synergistic effects of bacterial combinations might result in a more effective probiotic potential. We suspect that raw and fermented milk products from animals in Saudi Arabia, especially Laban made from camel milk, are rich in LAB and have promising probiotic potential.

Potential of lactic acid bacteria for the reduction of fumonisin exposure in African fermented maize based foods

Maize, which contributes to a large portion of the African diet and serves as the base substrate for many fermented cereal products, has been reported to be contaminated with fumonisins. This study aimed to evaluate thein vitro ability of predominant lactic acid bacteria (LAB) in African traditional fermented maize based foods (ogi andmahewu) to bind fumonisin B1 (FB1) and B2 (FB2), as well as the stability of the complex at different pH and temperatures, in particular observed duringogi fermentation and under its storage conditions (time, temperature). The percentage of bound fumonisins was calculated after analysing the level of fumonisins not bound to LAB after a certain incubation time, by HPLC. The results revealed the ability of all tested LAB strains to bind both fumonisins, with binding efficiencies varying between strains and higher for FB2. Binding of fumonisins increased with a decrease in pH from 6 to 4 (observed during theogi fermentation process) and from 4 to 2 (acidic pH in the stomach), and an increase in temperature (from 30 to 37 °C). The percentage of FB1 and FB2 bound to LAB at pH 4 decreased after 6 days of storage at 30 °C for all LAB strains, except forLactobacillus plantarum (R1096) for which it increased.Lactobacillus species (L. plantarum andLactobacillus delbrueckii) were the most efficient in binding FB1 and FB2, whereasPediococcus sp. was less efficient. Therefore, theLactobacillus strains tested in this study can be recommended as potential starter cultures for African traditional fermented maize based foods having detoxifying and probiotic properties.

Complete Genome Sequence of Lactobacillus plantarum 10CH, a Potential Probiotic Lactic Acid Bacterium with Potent Antimicrobial Activity.

ABSTRACTLactobacillus plantarum 10CH is a bacteriocin-producing potential probiotic lactic acid bacterium (LAB) strain isolated from cheese. Its complete nucleotide sequence shows a single circular chromosome of 3.3 Mb, with a G+C content of 44.51%, a 25-gene plantaricin bacteriocin gene cluster, and the absence of recognized virulence factors.

Bio-protective potential of lactic acid bacteria: Effect of Lactobacillus sakei and Lactobacillus curvatus on changes of the microbial community in vacuum-packaged chilled beef

ObjectiveThis study was to determine the bacterial diversity and monitor the community dynamic changes during storage of vacuum-packaged sliced raw beef as affected by Lactobacillus sakei and Lactobacillus curvatus.MethodsL. sakei and L. curvatus were separately incubated in vacuumed-packaged raw beef as bio-protective cultures to inhibit the naturally contaminating microbial load. Dynamic changes of the microbial diversity of inoculated or non-inoculated (control) samples were monitored at 4°C for 0 to 38 days, using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE).ResultsThe DGGE profiles of DNA directly extracted from non-inoculated control samples highlighted the order of appearance of spoilage bacteria during storage, showing that Enterbacteriaceae and Pseudomonas fragi emerged early, then Brochothrix thermosphacta shared the dominant position, and finally, Pseudomonas putida showed up became predominant. Compared with control, the inoculation of either L. sakei or L. curvatus significantly lowered the complexity of microbial diversity and inhibited the growth of spoilage bacteria (p<0.05). Interestingly, we also found that the dominant position of L. curvatus was replaced by indigenous L. sakei after 13 d for L. curvatus-inoculated samples. Plate counts on selective agars further showed that inoculation with L. sakei or L. curvatus obviously reduced the viable counts of Enterbacteraceae, Pseudomonas spp. and B. thermosphacta during later storage (p< 0.05), with L. sakei exerting greater inhibitory effect. Inoculation with both bio-protective cultures also significantly decreased the total volatile basic nitrogen values of stored samples (p<0.05).ConclusionTaken together, the results proved the benefits of inoculation with lactic acid bacteria especially L. sakei as a potential way to inhibit growth of spoilage-related bacteria and improve the shelf life of vacuum-packaged raw beef.

Exploring diversity and biotechnological potential of lactic acid bacteria from tocosh - traditional Peruvian fermented potatoes - by high throughput sequencing (HTS) and culturing

Lactic acid bacteria (LAB) diversity associated with tocosh, Peruvian traditional fermented potatoes, was for the first time investigated by culturing and high throughput sequencing (HTS) approaches. They were applied on three samples i.e. freshly harvested potatoes, one-month and eight-months production. While by culture-dependent approach a few Lactobacillus (Lb) species (Lb. sakei, Lb. casei, Lb. farciminis, Lb. brevis, Lb. fermentum) and Leuconostoc (Ln) mesenteroides were identified, twenty-four OTUs belonging to six LAB genera were considered in tocosh samples by HTS, being Lactobacillus dominant in all three samples. LAB predominated on fresh potatoes, while Clostridium, Zymophilus and Prevotella were the most abundant genus in 1- and 8-months tocosh samples. When biotechnological features were investigated, amylase and phytate-degrading abilities as well as EPS and group B vitamin (riboflavin and folate) production were exhibited by several Lb. sakei and Ln. mesenteroides strains. Safety traits of major LAB species from tocosh showed antibacterial activities as well as biogenic amines production capacity. The molecular inventory achieved by HTS approach provided information on LAB population composition during fermentation of this ancestral potato fermented product while culturing allowed the selection of LAB strains suitable for novel functional cultures design for the production of fermented starchy products.