Autochthonous Bacteria Research Articles

Characterization, screening, and application of bacteria with probiotic properties isolated from the gut of Labeo calbasu (Hamilton)

Abstract Labeo calbasu is not reared in aquaculture because of the unavailability of proper feed and the risk of infection. The ability of probiotics to promote growth and immunological defense barriers in the gut has led to the use of autochthonous probiotic bacteria. Hence, the present study was conducted to screen potential probiotic bacteria from the gut of L. calbasu and to supplement the same to study the effect on growth and immunity. Strains with probiotic properties were assayed for exogenous enzyme production and identified based on phylogenetic analysis and nucleotide homology. Four of nine isolates showed promising antibacterial activity against Aeromonas hydrophila. The strains survived in relatively low pH and high bile concentrations and were investigated for hydrophobicity, autoaggregation, and coaggregation. Based on the positive results of this study, the LC1 and LC4 strains (analysed with 16S rRNA gene sequencing and showing similarity with Aneurinibacillus aneurinilyticus and Stenotrophomonas sp.) were further incorporated into diets to explore their probiotic effects on the growth performance and immunity of the fish. Administering the probiotics elevated growth parameters and benefitted the immune system by increasing the phagocytic index and decreasing the mortality rate with exposure to A. hydrophila.

Enhanced nutritional value of chickpea protein concentrate by dry separation and solid state fermentation

Abstract A sustainable dry processing method to obtain nutritional and functional chickpea products was developed, yielding protein concentrates suited to prepare products without additives. Chickpeas were milled and air-classified into protein and starch-enriched concentrates. Subsequently, spontaneous solid state fermentation (SSF) with daily back-slopping was performed at 37 °C. The dominant autochthonous lactic acid bacteria (LAB) strains in chickpea flour and enriched fractions were Pediococcus pentosaceus and Pediococcus acidilactici. Strains were selected on their ability to metabolise flatulence-causing α-galactosides. SSF reduced the pH of the doughs in 24h from 6.6 to 4.2. After 72 h, concentrations of raffinose and stachyose were reduced by 88.3–99.1%, while verbascose became undetectable. Moreover, phytic acid reduced with 17% while total phenolic contents increased with 119%. Besides the observed differences in smell, texture and colour, the sourdoughs showed 67% higher water-holding capacity. This natural route to produce chickpea concentrates thus increases both the nutritive and technical functionality. Industrial relevance Increasing the sustainability of our food production is required to meet the demand for food of our growing world population. A processing route combining dry fractionation and solid state fermentation is developed to prepare chickpea concentrates with improved nutritional properties. This route is more sustainable as the use of water and thus energy-intensive drying steps are minimised. Moreover, it provides more natural ‘clean-label’ foods, i.e., foods with less additives and minimally processed. Solid state fermentation is used to reduce the presence of anti-nutritional factors, i.e., α-galactosides and phytic acid. Autochthonous LAB were accumulated via back-slopping and employed as starter culture as an alternative to the use of a commercial starter culture. Chickpea sourdoughs with enhanced nutritional quality of chickpea were obtained. The sourdough may be used directly to fortify cereal products like chickpea protein enriched bread or can be dried into a chickpea ingredient for many other applications as well.

In vitro selection of autochthonous lactic acid bacterium from clownfish Amphiprion ocellaris

In vitro selection of autochthonous lactic acid bacterium from clownfish <i>Amphiprion ocellaris</i>

The Human Skin Bacteria Staphylococcus epidermidis Fermentation End Product Ameliorates UVB-induced ROS Generation Through Production of Free Electrons

Autochthonous bacteria associated with browning in moromi fermentation were investigated, isolated and characterised. By cultured plating, only Bacillus spp. and Staphylococcus spp. were mainly observed. By reverse transcriptase-nested PCR-DGGE (RevT-nested PCR-DGGE), lactic acid bacteria (LAB) were primarily observed while Bacillus spp. and Staphylococcus spp. were only observed in particular stages of fermentation. The change of Maillard's reactants, particularly xylose and amino acids, as well as browning indicator were significant, when Bacillus and Staphylococcus were the main bacteria as mapping by RevT-nested PCR-DGGE. Extremely low browning indicator was found in moromi with more diverse autochthonous strains including Bacillus amyloliquefaciens, B. zhangzhouensis, B. pumilus, B. infantis S. condiment, Staphylococcus sp., S. carnosus, S. epidermidis and S. xylosus. Staphylococcus sp. SSB48, and B. amyloliquefaciens SSB6, with ability to ferment xylose and degrade melanoidin, were selected to test in moromi. These two isolates significantly reduced browning in moromi through melanoidin degradation without interfering with aromatic complexity and showed the best result in mature moromi fermented for one month. This study demonstrated the efficient method and potential source of target strains with novel properties. Additionally, the application of these autochthonous isolates was one of the potentially new biological means for browning reduction in soy sauce.

Role of Gut Dysbiosis in Liver Diseases: What Have We Learned So Far?

Accumulating evidence supports that gut dysbiosis may relate to various liver diseases. Alcoholics with high intestinal permeability had a decrease in the abundance of Ruminnococcus. Intestinal dysmotility, increased gastric pH, and altered immune responses in addition to environmental and genetic factors are likely to cause alcohol-associated gut microbial changes. Alcohol-induced dysbiosis may be associated with gut barrier dysfunction, as microbiota and their products modulate barrier function by affecting epithelial pro-inflammatory responses and mucosal repair functions. High levels of plasma endotoxin are detected in alcoholics, in moderate fatty liver to advanced cirrhosis. Decreased abundance of Faecalibacterium prausnitzii, an anti-inflammatory commensal, stimulating IL-10 secretion and inhibiting IL-12 and interferon-γ expression. Proteobacteria, Enterobacteriaceae, and Escherichia were reported to be increased in NAFLD (nonalcoholic fatty liver disease) patients. Increased abundance of fecal Escherichia to elevated blood alcohol levels in these patients and gut microbiota enriched in alcohol-producing bacteria produce more alcohol (alcohol hypothesis). Some undetermined pathological sequences related to gut dysbiosis may facilitate energy-producing and proinflammatory conditions for the progression of NAFLD. A shortage of autochthonous non-pathogenic bacteria and an overgrowth of potentially pathogenic bacteria are common findings in cirrhotic patients. The ratio of the amounts of beneficial autochthonous taxa (Lachnospiraceae + Ruminococaceae + Veillonellaceae + Clostridiales Incertae Sedis XIV) to those of potentially pathogenic taxa (Enterobacteriaceae + Bacteroidaceae) was low in those with early death and organ failure. Cirrhotic patients with decreased microbial diversity before liver transplantation were more likely to develop post-transplant infections and cognitive impairment related to residual dysbiosis. Patients with PSC had marked reduction of bacterial diversity. Enterococcus and Lactobacillus were increased in PSC patients (without liver cirrhosis.) Treatment-naive PBC patients were associated with altered composition and function of gut microbiota, as well as a lower level of diversity. As serum anti-gp210 antibody has been considered as an index of disease progression, relatively lower species richness and lower abundance of Faecalibacterium spp. in gp210-positive patients are interesting. The dysbiosis-induced altered bacterial metabolites such as a hepatocarcinogenesis promotor DCA, together with a leaky gut and bacterial translocation. Gut protective Akkermansia and butyrate-producing genera were decreased, while genera producing-lipopolysaccharide were increased in early hepatocellular carcinoma (HCC) patients.

Effects of a Groundwater Heat Pump on Thermophilic Bacteria Activity

Groundwater samples were collected from the tubular wells of a groundwater heat pump (GWHP), and the psychrophilic, mesophilic, and thermophilic bacteria inhabiting the collected groundwater were cultured and isolated. Using the isolated bacteria, we analyzed temperature-dependent changes in autochthonous bacteria based on the operation of the GWHP. Microbial culture identified eight species of bacteria: five species of thermophilic bacteria (Anoxybacillus tepidamans, Bacillus oceanisediminis, Deinococcus geothermalis, Effusibacillus pohliae, and Vulcaniibacterium thermophilum), one species of mesophilic bacteria (Lysobacter mobilis), and two species of psychrophilic bacteria (Paenibacillus elgii and Paenibacillus lautus). The results indicated A. tepidamans as the most dominant thermophilic bacterium in the study area. Notably, the Anoxybacillus genus was previous reported as a microorganism capable of creating deposits that clog above-ground wells and filters at geothermal power plants. Additionally, we found that on-site operation of the GWHP had a greater influence on the activity of thermophilic bacteria than on psychrophilic bacteria among autochthonous bacteria. These findings suggested that study of cultures of thermophilic bacteria might contribute to understanding the bio-clogging phenomena mediated by A. tepidamans in regard to GWHP-related thermal efficiency.

Solar photocatalytic disinfection using ink-jet printed composite TiO2/SiO2 thin films on flexible substrate: Applicability to drinking and marine water

Hybrid TiO2/SiO2 thin films deposited by material printing technique on flexible substrates were prepared, characterized and tested for solar photocatalytic disinfection. Effect of surface hydrophilicity/hydrophobicity of printed coatings on photocatalytic disinfection was studied by means of (i) drinking water contaminated with natural consortia of fecal bacteria (gram-negative: Escherichia coli and total coliforms; gram-positive: Enterococci), and (ii) seawater containing pathogenic gram-negative bacteria (Vibrio owensii, Vibrio alfacsensis and Vibrio harveyi). Inactivation of gram-negative bacteria in drinking water with fecal contamination by solar photocatalysis was slightly more efficient than solar disinfection, while for gram-positive bacteria similar efficiency was observed. These results, in combination with observed release of titanium from coatings (detected by means of inductively coupled plasma atomic emission spectrometer), indicate that TiO2/SiO2 needs further improvements for solar photocatalytic disinfection of drinking water. Efficiency of seawater disinfection towards gram-negative Vibrio spp. (Vibrio owensii, Vibrio alfacsensis and Vibrio harveyi) was significantly enhanced when TiO2/SiO2 coatings were used under natural solar light. Moreover, hydrophobic thin films led to faster Vibrio spp. inactivation as compared to hydrophilic ones, which was attributed to higher bacteria adhesion on hydrophobic coatings. However, decrease of photocatalytic activity of hydrophobic TiO2/SiO2 coatings was observed after ten experimental cycles mainly due to deposition of salts on the surface of photocatalyst. Generally, results of this study suggest that autochthonous bacteria such as Vibrio spp. in seawater are significantly more resistant to solar disinfection in comparison with not autochthonous bacteria such as Escherichia coli, total coliforms and Enterococci in contaminated drinking water.

Autochthonous lactic acid bacteria-presentation of potential probiotics application.

The objective of this study was to evaluate the probiotic potential as well as the ability of adhesion and aggregation of natural and autochthonous lactic acid bacteria, isolated from traditionally made cheese. Lactic acid bacteria from natural food sources can be promising probiotic candidates and they can be used in natural food preservation or like starter cultures. Tested autochthonous isolates showed tolerance to the simulated gastrointestinal condition as well as the sensitivity to clinically relevant antibiotics, especially to ampicillin (MIC at 0.195μgmL-1 for lactobacilli and from 0.195 to 3.125μgmL-1 for lactococci). Among isolates, the highest percentage of adhesion was detected with chloroform, while the adhesion ability of selected isolates to pig intestinal epithelium was in the correlation with the results of adhesion ability with solvents. The auto-aggregation ability of isolates was demonstrated, while co-aggregation with Escherichia coli was strain specific. The results indicated the potential probiotic properties of the isolates and give evidence for further investigation and potential application in the dairy industry.

Synergistic effects of autochthonous probiotic bacterium and Mentha piperita diets in Catla catla (Hamilton, 1822) for enhanced growth and immune response

Two dietary experiments were performed to evaluate the impact of the herb Mentha piperita as a dietary supplement on Catla catla. In Experiment 1, fingerlings (0.45–2.60 g) were fed on diets supplemented with M. piperita at different levels (P1, P2, P3, and P4 at 2, 4, 6, and 8 g Kg−1 of feed) and C1 served as the control with no peppermint supplementation. In Experiment 2, fingerlings (0.40–3.15 g) were fed with diets containing autochthonous probiotic bacteria Bacillus coagulans (3000 colony forming unit g−1) along with M. piperita (PP1-PP4 at 2, 4, 6, and 8 g Kg−1 of feed) and feed C2 served as control containing probiotics but no peppermint. Significantly (P < 0.05) high values of growth parameters, digestive enzyme activities, low reed conservation ratio, low excretion of ammonia, and orthophosphates were observed in fingerlings fed with P3 for Experiment 1 and PP3 for Experiment 2. Hematological counts, phagocytic activity, and respiratory burst activity were also enhanced in fingerlings fed with M. piperita supplementation revealing that dietary administration of peppermint at optimum level can enhance the growth, digestibility, and immunity of C. catla fingerlings; however, incorporation of B. coagulans showed better growth and immunity revealing that synergistic effects of M. piperita and autochthonous probiotic in C. catla diets can lead to its sustainable aquaculture.

Screening of autochthonous lactic acid bacteria strains from artisanal soft cheese: probiotic characteristics and prebiotic metabolism

Today's growing interest in functional foods is due to their positive impacts on human health. The aim of this study was to evaluate the probiotic properties and prebiotic metabolism of autochthonous lactic acid bacteria from artisanal Serpa cheese. Twenty strains presented better tolerance to stress conditions found in the gastrointestinal tract, highlighting Lactobacillus brevis C1Lb21 for its adequate auto-aggregating ability and significantly higher hydrophobicity. However, eight strains were discarded for their antibiotic resistance and biogenic amine production. Finally, prebiotic fermentation study showed that lactulose supported better growth of lactobacilli and induced the production of short-chain fatty acids (SCFA). During lactulose fermentation, Lb. pentosus G4Lb7 produced statistically more SCFA, and Lb. plantarum G1Lb5 lactic acid. Thus, Lb. brevis C1Lb21, Lb. plantarum G1Lb5 and Lb. pentosus G4Lb7 are promising probiotic candidates, and in combination with lactulose could be used for developing a symbiotic cheese.

Functional and technological properties of exopolysaccharide producing autochthonous Lactobacillus plantarum strain AAS3 from dry fish based fermented food

The present study was aimed to evaluate the disparate functional and technological properties of exopolysaccharide (EPS) producing potent Lactobacillus sp. Initially, 10 autochthonous probiotic bacteria were isolated from Hentak and screened for EPS production. Among them, Lactobacillus plantarum strain AAS3 was identified as maximum producer of EPS (450.5 ± 5.8 mg/L) and assessed further for evaluating functional and technological attributes using standard methodologies. Strain AAS3 maintained its viability towards simulated gastric juice (pH 2.0) with total cell counts of 2.4 ± 0.06 log cfu/mL. The isolate showed pronounced β-galactosidase activity (18.3 ± 0.6 U/mL), bile salt hydrolase production (3.32 ± 0.5 U/mL), and cholesterol reducing property (41.6 ± 0.8%). Propitious antioxidant traits of strain AAS3 were observed in terms of scavenging hydroxyl radicals. The isolate sustained high concentrations of NaCl, fermented distinctive carbohydrates, and produced important hydrolytic enzymes. Further, strain AAS3 displayed promising autolytic property (56.4 ± 1.2%), catalase activity (22.34 ± 0.3 AU), and nitrite production (28.2 ± 0.8 mM nitrite/mg dry weight). Most importantly, the isolate showed not only negative results towards in vitro haemolytic, DNase, and gelatinase tests but also sensitivity to conventional antibiotics tested. In conclusion, pronounced EPS production, exemplary functional and technological traits, and safety aspects signify suitability of L. plantarum strain AAS3 in food processing industries as quintessential adjunct/starter culture.

Microbiota of Sardinian Goat's Milk and Preliminary Characterization of Prevalent LAB Species for Starter or Adjunct Cultures Development.

This work was performed to study the microbiota of raw goat's milk (67 samples) collected in different areas of Sardinia, in order to select autochthonous lactic acid bacteria (LAB) strains for use in goat cheese manufacturing. Total mesophilic bacteria ranged between 105 and 107 cfu/mL; mean counts of Enterobacteriaceae did not exceed 4 log cfu/mL whereas those of E. coli and coagulase-positive staphylococci were lower than 1.5 and 2 log ufc /ml, respectively. Neither Salmonella spp. nor Listeria monocytogenes were recovered. The numbers of total LAB were in the range from 104 to 107 cfu/mL and mean yeasts counts varied between 103 and 105 cfu/mL. The most frequently isolated LAB species were Lactococcus lactis subsp. lactis and Lactobacillus paracasei. The presence of Enterococcus faecium was also noteworthy. The in vitro study of some functional characteristics related to technological properties of the strains belonging to these species allowed to point out some strains possessing good potential for use as adjunct or starter cultures in the production of cheese.

ЕКОЛОГІЧНИЙ АНАЛІЗ УМОВНО-ПАТОГЕННОЇ МІКРОФЛОРИ ПРИ ПНЕВМОНІЯХ

Actuality: Purulent-inflammatory diseases of the respiratory tract are more often induced (under the influence of different triggers) by endogenous microflora. One of the factors that determine the appropriateness of the choice of antibiotics and, therefore, the beneficial outcome of the disease is the microbial spectrum of causative agents of infection. At the present time, there is increasing information on changes in the composition of human microbiota at various diseases and its role in the pathogenesis of various disorders, including respiratory diseases. Objective: Studying the species composition of the microflora in non-hospital pneumonia and the determination of the participation of different species in the structure of microbiocenosis. Materials and methods: Bacteriological research of various clinical materials from 336 patients with pneumonia is conducted. Microbiological examination included an isolation of pathogens, identification by morphological, cultural and biochemical properties. An ecological analysis of the microflora of clinical material was carried out by studying its structure and functional characteristics using indicators such as the index of constancy, the Berger-Parker domination index. Results and discussion: During the study of micro-ecological indicators of microflora of patients with pneumonia, the distribution of endogenous microorganisms of nasopharynx in the biocenosis of lungs was revealed, which was confirmed by the indices of constancy and the dominance of Berger-Parker. In the etiological spectrum of infectious factors, fungi of the genus Candida and streptococci of viridans group, which had a high colonization level, were prevailed. Microorganisms were isolated in both a monocultural and associative form, which contained two to five species. Combinations of bacteria and fungi of the genus Candida were the most common, which were registered at 80.7 % (152/187). The associations included not only autochthonous bacteria but also non-specific habitats such as K. pneumoniae, P. aeruginosa, E. coli, E. cloacae, E. aerogenes, E. faecalis, E. faecium, P. vulgaris, P. mirabilis, C. xerosis and A. baumonii. Conclusion: The obtained data have shown that the lungs of patients with pneumonia are actively colonized by the representatives of the microflora of the nasopharynx with certain qualitative and quantitative changes of microbiocenosis. This is manifested in the emergence of transient and random opportunistic microorganisms against the background of reduced domination of the autochthonous microflora of the nasopharynx. Fungi of the genus Candida and streptococci of the viridans group were predominant among the other isolated opportunistic microorganisms and characterized by high colonization levels.

CARACTERIZAÇÃO PARCIAL PROBIÓTICA E MOLECULAR DE BACTÉRIAS ÁCIDO LÁCTICAS ISOLADAS DE QUEIJO DE COALHO DA CIDADE DE ARCOVERDE – PERNAMBUCO

O conhecimento da biodiversidade das cepas de bactérias ácido lácticas autóctones é muito importante para a produção de queijo de coalho com qualidade, pois as BAL atuam na inibição do crescimento de microrganismos indesejáveis por competição ou pela ação de proteínas antimicrobianas denominadas bacteriocinas por elas sintetizadas. Além dos efeitos probióticos apontados por pesquisas, com benefícios para a saúde humana. Por isso, esse trabalho teve por objetivo a caracterização parcial probiótica de bactérias ácido lácticas isoladas de queijo de coalho da cidade de Arcoverde – Pernambuco. As bactérias ácido lácticas utilizadas foram previamente isoladas do queijo de coalho da cidade de Arcoverde-PE e conservadas sob refrigeração no Centro de Apoio à pesquisa-Cenapesq. Foram usadas 11 cepas bacterianas diferentes para os testes. As BAL foram submetidas ao teste de resistência ao valor de pH baixo, resistência à presença de sais biliares, atividade antagonista e caracterização molecular, seguindo parâmetros da Agência Nacional de Vigilância Sanitária. Das 11 bactérias isoladas da cidade de Arcoverde-PE apenas duas foram eficientes para a maioria dos testes e identificadas como Enterococcus, demonstrando o seu potencial probiótico. Portanto, percebemos que bactérias isoladas do queijo de coalho pernambucano representam importante fonte de microrganismos benéficos para a tecnologia de alimentos e saúde humana e animal.

Metataxonomics of Tunisian phosphogypsum based on five bioinformatics pipelines: Insights for bioremediation

Phosphogypsum (PG) is an acidic by-product from the phosphate fertilizer industry and it is characterized by a low nutrient availability and the presence of radionuclides and heavy metals which pose a serious problem in its management. Here, we have applied Illumina MiSeq sequencing technology and five bioinformatics pipelines to explore the phylogenetic communities in Tunisian PG. Taking One Codex as a reference method, we present the results of 16S-rDNA-gene-based metataxonomics abundances with four other alternative bioinformatics pipelines (MetaGenome Rapid Annotation using Subsystem Technology (MG-RAST), mothur, MICrobial Community Analysis (MICCA) and Quantitative Insights into Microbial Ecology (QIIME)), when analyzing the Tunisian PG. Importantly, based on 16S rDNA datasets, the functional capabilities of microbial communities of PG were deciphered. They suggested the presence of PG autochthonous bacteria valorizable into (1) removal of radioactive elements and toxic heavy metals, (2) promotion of plant growth, (3) oxidation and (4) reduction of sulfate. These bacteria can be explored further for applications in the bioremediation of by-products, like PG, by different processes.

Prevalence, Genetic Diversity, and Technological Functions of the Lactobacillus sanfranciscensis in Sourdough: A Review.

The use of sourdough asaleavening agent in bread making is a very old method that can be traced back to ancient times. Sourdoughs harbor a complex microbiota that is affected by multiple factors including factors related to cereal plants, grains, and sourdough processing techniques. Lactobacillus sanfranciscensis is the key autochthonous bacterium of the traditional sourdough microbiota and it is said to be "sourdough adapted" species. Despite the great dominance of this bacterium in sourdoughs, the origin of this species still remains unclear. Lactobacillus sanfranciscensis positively influences all aspects of sourdough and fermented foods. However, the positive influence of this species on sourdough is a strain-dependent characteristic. The first purpose of this review was to discuss factors affecting the microbiota of sourdoughs with particular emphasis on reasons behind the remarkable prevalence of L. sanfranciscensis in this ecological niche. The second objective was to discuss the genotypic and phenotypic classification of L. sanfranciscensis strains and the influence of this species on technological and functional characteristics of sourdough including its influence on rheological properties of dough and bread characteristics, texture, aroma, and shelf-life through the inhibition of fungal growth.

Administration of host‐derived probiotics does not affect utilization of soybean meal enriched diets in juvenile turbot (Scophthalmus maximus)

In today's aquaculture, the cost-intensive and scarce fishmeal is increasingly replaced by plant-based feedstuff such as soybean meal (SBM). However, SBM contains saponins which can have adverse effects on fish's digestive tract potentially culminating in severe enteritis. In a 60 day feeding trial we studied the use of autochthonous bacteria as probiotics upon SBM supplementation on juvenile turbot. Growth performance, feed conversion, body composition and health status were assessed for five different treatment groups, comprising a fishmeal control (FM ctrl), a SBM control without probiotics (SBM ctrl) and three multi-species probiotic treatments. For the production of the probiotic treatments a basal diet with a composition identical to the SBM ctrl including 40% SBM of total dry matter likewise was prepared. The basal diet was stepwise top coated with three different probiotic supplementations: (a) three distinct isolates with saponin-metabolizing ability (SBM + degrad); (b) three distinct isolates inhibitory towards the pathogen, Tenacibaculum maritimum (SBM + anta); and (c) a commercial probiotic application (SBM + com). Individual weight gain was highest in FM ctrl but only SBM + degrad diet showed a significantly lower value (p < 0.05). The feed conversion ratio was lowest in FM ctrl and significantly higher in SBM + degrad (p < 0.01). The protein retention efficiency did only differ significantly between FM ctrl and SBM + degrad (p < 0.05), whereas lipid retention efficiency remained unaffected. Whole body composition and gross energy content were similar in all treatments lacking significant differences. The condition factor was significantly elevated in SBM + degrad compared to FM ctrl (p < 0.05). Hematocrit was highest in FM ctrl and significantly lower in the other treatments (p < 0.01) with SBM + com accounting for the lowest value (p < 0.001). The hepatosomatic index was slightly increased in FM ctrl but no significant difference was detected. Regarding the spleen somatic index SBM + anta treatment revealed the highest and SBM ctrl a significantly lower value (p < 0.05). In conclusion, the growth performance of fish did not benefit from the different probiotic treatments, while body composition and gross energy content remained at an appropriate level. Moreover, the overall health status was on a sufficient level in all treatments which confirms the high dietary tolerability of our putative probiotic isolates by the fish.

Autochthonous microbes and their key properties in browning reduction during soy sauce fermentation

Autochthonous bacteria associated with browning in moromi fermentation were investigated, isolated and characterised. By cultured plating, only Bacillus spp. and Staphylococcus spp. were mainly observed. By reverse transcriptase-nested PCR-DGGE (RevT-nested PCR-DGGE), lactic acid bacteria (LAB) were primarily observed while Bacillus spp. and Staphylococcus spp. were only observed in particular stages of fermentation. The change of Maillard's reactants, particularly xylose and amino acids, as well as browning indicator were significant, when Bacillus and Staphylococcus were the main bacteria as mapping by RevT-nested PCR-DGGE. Extremely low browning indicator was found in moromi with more diverse autochthonous strains including Bacillus amyloliquefaciens, B. zhangzhouensis, B. pumilus, B. infantis S. condiment, Staphylococcus sp., S. carnosus, S. epidermidis and S. xylosus. Staphylococcus sp. SSB48, and B. amyloliquefaciens SSB6, with ability to ferment xylose and degrade melanoidin, were selected to test in moromi. These two isolates significantly reduced browning in moromi through melanoidin degradation without interfering with aromatic complexity and showed the best result in mature moromi fermented for one month. This study demonstrated the efficient method and potential source of target strains with novel properties. Additionally, the application of these autochthonous isolates was one of the potentially new biological means for browning reduction in soy sauce.

Contribution of autochthonous lactic acid bacteria to the typical flavour of raw goat milk cheeses

In this study, a collection of 298 wild strains of lactic acid bacteria (LAB) isolated from raw goat milk cheeses, belonging to 8 genera and 24 species, was investigated for their ability to generate volatile compounds. Sensory evaluation showed that goat milk cultures of Leuconostoc and Lactococcus strains reached the highest scores for dairy odour attributes. Fifty six LAB strains with the highest sensory evaluation scores (one per each ten, or fraction, of those belonging to the same species) were selected for gas chromatography–mass spectrometry (GC–MS) analysis. A total of 34 volatile compounds (five carboxylic acids, eleven alcohols, six aldehydes, six ketones, one ester, and five miscellaneous compounds) were detected in lactic curds made with each one of 56 selected LAB strains. The number of volatile compounds in individual curds varied from 15 to 33 while the total abundance of volatile compounds in individual curds ranged from 1.98- to 17.50-fold the total abundance in uninoculated curd. Major differences in volatile generation were related to amino acid catabolism.

Control of Autochthonous Spoilage Lactic Acid Bacteria in Apple and Orange Juices by Sensorially Accepted Doses of Citrus Spp. Essential Oils Combined with Mild Heat Treatments.

This study assessed the compromised acceptance threshold (CAT) and rejection threshold (RT) of Citrus lemon (CLEO) and Citrus reticulata essential oil (CREO) in apple and orange juices. The efficacy of CLEO and CREO concentrations below the RT were evaluated alone and combined with mild heat treatment (MHT) (54 °C, up to 12 min) to inactivate the autochthonous spoilage bacteria Lactobacillus brevis, Lactobacillus plantarum, and Leuconostoc mesenteroides in apple and orange juices. The CAT of CLEO and CREO varied from 0.15 to 0.17μL/mL in orange and apple juices. The RT of CLEO was approximately 0.58μL/mL in apple and orange juices, and the RT of CREO was 0.68μL/mL in both juices. When CLEO and CREO were assayed alone, the highest concentration (0.50μL/mL) decreased counts of all strains approximately 2 log10 CFU/mL after 12 min of exposure to 54 °C. All concentrations of CLEO or CREO in combination with MHT acted synergistically against L. brevis, L. plantarum, and L. mesenteroides. Decreases in counts varied with the strain, CLEO and CREO concentrations, juice type, and exposure time to the combined treatment. CREO was more effective than CLEO in combination with MHT against the strains in apple and orange juices. Effective combinations of CLEO or CREO with MHT to control the autochthonous spoilage bacteria did not compromise the quality parameters (°Brix, pH, and titratable acidity) that characterize unsweetened juices. These results indicate CLEO or CREO at concentrations below the sensory RT in combination with MHT as a feasible technology to control autochthonous spoilage bacteria in fresh fruit juices. PRACTICAL APPLICATION: The present study provides novel information concerning the efficacy of sensorially accepted doses of CLEO and CREO combined with MHT against autochthonous spoilers in fruit juice. The valuable synergistic effects that can be observed when combining CLEO and CREO with MHT reveal a feasible preservation technology and alternative to traditional treatments that are successful because they help reduce treatment intensity, thereby avoiding adverse effects on the sensory, physicochemical, and nutritional properties of these products.