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1.
Fifty-one yeast strains isolated from fermented mash of Balinese rice wine, brem, fermented using five different types of starters, ragi tape, were identified on the basis of their internal transcribed spacer (ITS) regions and their 18S rDNA sequences. The results revealed that Saccharomyces cerevisiae(35 strains), Candida glabrata(six strains), Pichia anomala(three strains) and Issatchenkia orientalis(seven strains) were the main yeasts in the fermentation of the rice wine. These yeasts undergo succession during the fermentation in which S. cerevisiae was mostly found as the principal yeast at the end of fermentation. Phylogenetic analysis based on the 18S rDNA sequences of selected strains placed the isolated S. cerevisiae strains in the Saccharomyces sensu stricto group. Karyotype analysis of the S. cerevisiae strains resolved using pulsed field gel electrophoresis (PFGE) showed that the strains are typically associated with different types of starters.  相似文献   

2.
The toxigenic potential of Bacillus species isolated from the traditional fermented condiment okpehe was determined; this is aimed at selection of non-toxigenic bacilli as starter cultures to bring about production of safe product. B. subtilis and B. cereus strains isolated from okpehe were evaluated for their possible possession of virulence characteristics. Fifty isolates were screened for their ability to produce diarrhoea enterotoxin by reversed passive latex agglutination (BCET-RPLA) test kit; the result showed that 40% of the B. cereus strains were toxigenic. The ability of the selected isolates to compete in situ and in vitro toxin production during the fermentation was also determined. The enterotoxin was not detected using BCET-RPLA kit in the spontaneously fermented samples of okpehe, but the toxin was detected in the okpehe samples fermented using B. cereus enterotoxin producer in mixed starter culture fermentation. The PCR amplification of virulence genes revealed that Bacillus cereus and B. licheniformis, a strain from the B. subtilis group, contained DNA sequences encoding the haemolysin BL (hblD) enterotoxin complex. The growth ability of B. cereus strains to high population during the fermentation and the presence of detectable diarroheagenic genes in B. cereus and B. licheniformis showed that strains carrying virulence characteristics cannot be totally ruled out in traditionally fermented okpehe.  相似文献   

3.
Controlled fermentation of maize was carried out using six strains of Lactobacillus fermentum and one strain of yeast, Saccharomyces cerevisiae, isolated from traditionally fermented maize dough as starter cultures for inoculum enrichement. The fermentations were monitored by pH, acidity, microbiological analysis and taste panel evaluation of two products, kenkey and koko, prepared from the fermented doughs. The strains of L. fermentum used as starter culture dominated the microflora during fermentation and in most inoculated doughs the required pH was attained by 24 h instead of 48 h of dough fermentation. Higher contents of lactic acid bacteria and yeasts were observed in inoculated doughs at the initial stages of fermentation but the spontaneously fermented doughs attained similar lactic acid bacteria and yeasts counts by 24 h of dough fermentation. The organoleptic quality of kenkey and koko prepared from doughs fermented with starter culture for 48 h was not significantly different from the traditional products. Kenkey prepared from doughs fermented for 24 h with starter culture were found to be unacceptable by the taste panel although similarly produced koko was acceptable.The authors are with the Food Research Institute, Council for Scientific and Industrial Research, P.O Box M 20. Accra, Ghana.  相似文献   

4.
Aims: To select appropriate micro‐organisms to be used as starter culture for reliable and reproducible fermentation of Lafun. Methods and Results: A total of 22 cultures consisting of yeast, lactic acid bacteria (LAB) and Bacillus cereus strains predominant in traditionally fermented cassava during Lafun processing were tested as potential starter cultures. In an initial screening, Saccharomyces cerevisiae 2Y48P22, Lactobacillus fermentum 2L48P21, Lactobacillus plantarum 1L48P35 and B. cereus 2B24P31 were found to be the most promising of the cultures and were subsequently tested in different combinations as mixed starter cultures to ferment submerged cassava roots. Saccharomyces cerevisiae, inoculated singly or combined with B. cereus, gave the softest cassava root after 48 h of fermentation according to determination of compression profile and stress at fracture. Overall, sensory quality testing showed that Lafun obtained from S. cerevisiae‐fermented cassava gave the most preferred stiff porridge. Saccharomyces cerevisiae 2Y48P22 showed pectinase production in a model system. Conclusions: The results suggest that S. cerevisiae 2Y48P22 is the most efficient organism for cassava softening during the fermentation. Therefore, it could be combined with LAB and used as starter for Lafun processing. Significance and Impact of the Study: Starter cultures are made available for controlled fermentation of Lafun.  相似文献   

5.
The microbial community dynamics play an important role during Massa Medicata Fermentata (MMF) fermentation. In this study, bacterial and fungal communities were investigated based on the culture-dependent method and polymerase chain reaction-denaturing gradient gel electrophoresis analysis. Meanwhile the dynamic changes of digestive enzyme activities were also examined. Plating results showed that MMF fermentation comprised two stages: pre-fermentation stage (0–4 days) was dominated by bacterial community and post-fermentation stage (5–9 days) was dominated by fungal community. The amount of bacteria reached the highest copy number 1.2?×?1010 CFU/g at day 2, but the fungi counts reached 6.3?×?105 CFU/g at day 9. A total of 170 isolates were closely related to genera Enterobacter, Klebsiella, Acinetobacter, Pseudomonas, Mucor, Saccharomyces, Rhodotorula, and Amylomyces. DGGE analysis showed a clear reduction of bacterial and fungal diversity during fermentation, and the dominant microbes belonged to genera Enterobacter, Pediococcus, Pseudomonas, Mucor, and Saccharomyces. Digestive enzyme assay showed filter paper activity; the activities of amylase, carboxymethyl cellulase, and lipase reached a peak at day 4; and the protease activity constantly increased until the end of the fermentation. In this study, we carried out a detailed and comprehensive analysis of microbial communities as well as four digestive enzymes' activities during MMF fermentation process. The monitoring of bacterial and fungal biodiversity and dynamics during MMF fermentation has significant potential for controlling the fermentation process.  相似文献   

6.
刘凡  周新虎  陈翔  陈坚  堵国成  方芳 《微生物学报》2018,58(12):2087-2099
【目的】解析江苏洋河酒厂浓香型白酒窖内发酵过程酒醅微生物群落结构,建立酒醅微生物与主要有机酸合成的关联性。【方法】通过宏基因组测序获得白酒发酵过程中微生物群落结构变化规律,利用主成分分析和偏最小二乘回归分析寻找酒醅中影响主要有机酸合成的关键微生物。【结果】根据微生物组成结构变化和有机酸合成变化规律,可将白酒窖内发酵分为两个时期(0–14 d和15–60 d)。其中窖内发酵0–15 d与主要有机酸合成相关的微生物数量显著高于15–60 d的。窖内发酵过程与主要有机酸合成相关的微生物包括7个菌属,分别为乳杆菌属(Lactobacillus)、葡萄球菌属(Staphylococcus)、酵母属(Saccharomyces)、Naumovozyma、伊萨酵母属(Issatchenkia)、嗜冷芽孢杆菌属(Psychrobacillus)和根霉属(Rhizopus)。【结论】本研究识别了白酒窖内发酵过程中与主要有机酸合成相关的核心和关键微生物,可为阐明白酒窖内发酵产酸机理和保障白酒品质的稳定性奠定研究基础和理论依据。  相似文献   

7.
Aquatic macrophytes such as Elodea nuttalli, Vallisneria natans, Alterranthera philoxerides that are widely distributed in water environments of Lake Taihu basin were used as substrate of solid state fermentation to produce crude protein extraction. The effects of single-strain fermentation and mixed strains fermentation of aquatic macrophytes on the production of crude protein extraction and cellulase activity are analyzed, respectively. The experimental results showed that the crude protein content of products with mixed strains fermentation is higher than that with single-strain fermentation. The crude protein content of V. natans fermented by Aspergillus niger and Candida utilis is the highest among the aquatic macrophytes examined in this study. V. natans is used as the substrate to be fermented by C. utilis and A. niger; their ratio is 1:1 at 28 ± 1 °C for 72 h. The crude protein of fermented V. natans is as high as 49.54%, with 128.82% of its increase rate. The cellulose activity reaches a maximum of 4.21 μ/ml at 84 h of fementation of V. natans. Thus, the solid state fermentation of aquatic macrophytes to produce crude protein extraction is promising, which make aquatic macrophytes a potential resource and thus is beneficial to the long-term ecological restoration of eutrophic lakes.  相似文献   

8.
Natto is a traditional Japanese food made from soybeans fermented by strains of Bacillus subtilis natto. It gives off a strong ammonia smell during secondary fermentation, and the biochemical basis for this ammonia production was investigated in this study. When natto was fermented by strain r22, ammonia production was shown to involve degradation of soybean proteins releasing amino acids, and only the glutamate contained in the natto obviously decreased, while the other amino acids increased during secondary fermentation. Strain r22 has two active glutamate dehydrogenase genes, rocG and gudB, and inactivating both genes reduced ammonia production by half, indicating that deamination of glutamate was one of the major ammonia-releasing reactions. In addition, urease encoded by ureABC was found to degrade urea during secondary fermentation. A triple mutant lacking rocG, gudB, and ureC exhibited minimal ammonia production, suggesting that the degradation of urea might be a further ammonia-releasing reaction.  相似文献   

9.

Aims

To evaluate the interaction between selected yeasts and bacteria and associate their metabolic activity with secondary cucumber fermentation.

Methods and Results

Selected yeast and bacteria, isolated from cucumber secondary fermentations, were inoculated as single and mixed cultures in a cucumber juice model system. Our results confirmed that during storage of fermented cucumbers and in the presence of oxygen, spoilage yeasts are able to grow and utilize the lactic and acetic acids present in the medium, which results in increased brine pH and the chemical reduction in the environment. These conditions favour opportunistic bacteria that continue the degradation of lactic acid. Lactobacillus buchneri, Clostridium bifermentans and Enterobacter cloacae were able to produce acetic, butyric and propionic acids, respectively, when inoculated in the experimental medium at pH 4·6. Yeast and bacteria interactions favoured the survival of Cl. bifermentans and E. cloacae at the acidic pH typical of fermented cucumbers (3·2), but only E. cloacae was able to produce a secondary product.

Conclusions

The methodology used in this study confirmed that a complex microbiota is responsible for the changes observed during fermented cucumber secondary fermentation and that certain microbial interactions may be essential for the production of propionic and butyric acids.

Significance and Impact of the Study

Understanding the dynamics of the development of secondary cucumber fermentation aids in the identification of strategies to prevent its occurrence and economic losses for the pickling industry.  相似文献   

10.
Raw meat sausage represents a unique ecological niche rich in nutrients for microbial consumption, making it particularly vulnerable to microbial spoilage. Starter cultures are applied to improve product stability and safety as well as flavour characteristics. However, the influence of starter cultures on microbial community assembly and succession throughout the fermentation process is largely unknown. In particular the effect on the fungal community has not yet been explored. We evaluate the microbiological status of four different raw meat sausages using high-throughput 16S rRNA gene and ITS2 gene sequencing. The objective was to study temporal changes of microbial composition during the fermentation process and to identify potential keystone species that play an important role within the microbial community. Our results suggest that fungi assigned to the species Debaryomyces hansenii and Alternaria alternata play a key role in microbial community dynamics during fermentation. In addition, bacteria related to the starter culture Lactobacillus sakei and the spoilage-associated genera Acinetobacter, Pseudomonas and Psychrobacter are central components of the microbial ecosystem in raw fermented sausages. Elucidating the exact role and interactions of these microorganisms has the potential to have direct impacts on the quality and safety of fermented foods.  相似文献   

11.
In this study, fermentation was employed as a tool to further increase the bioactive potential of processing by-product from a brown seaweed, Ecklonia cava, which can be obtained from food and cosmetic industries after its polyphenol extraction. The fermentation process was done for 24 h using an industrially important microorganism Candida utilis prior to being extracted with 80 % ethanol. The anti-inflammatory potential of the fermented E. cava processing by-product extract (FEPBE) was evaluated in vitro. The phlorotannin-rich FEPBE dose-dependently inhibited the nitric oxide production, prostaglandin-E2 production and suppressed the inducible nitric oxide synthase and cyclooxygenase-2 expressions in lipopolysaccharide-stimulated RAW 264.7 cells. The release of pro-inflammatory cytokines, interleukin-1β and interleukin-6, was significantly suppressed by the extract in a dose-dependent manner. Due to the profound anti-inflammatory activity, FEPBE appears as a value-added biomass fraction that can be exploited in numerous industrial applications as a source of functional ingredients.  相似文献   

12.
The objectives of this study were to evaluate the potential of gabiroba Campomanesia pubescens (DC) O. Berg in the production of a beverage fermented using selected and wild yeasts from indigenous fermentation, analyze the volatile compounds profile present during the process of fermentation, and evaluate the sensory quality of the final beverage produced. Throughout the process of fermentation, when Saccharomyces cerevisiae UFLA CA 1162 was inoculated, there were stable viable populations around 9 log cells ml−1. During indigenous fermentation, yeast population increased from 3.7 log CFU ml−1 to 8.1 log CFU ml−1 after 14 days. The diversity and dynamics of the yeast population during indigenous fermentation observed by PFGE analysis showed five different karyotyping profiles in the first days of fermentation. After the seventh day, there was a higher frequency of a similar S. cerevisiae profile. The yeast non-Saccharomyces were identified by sequencing of the ITS region as Candida quercitrusa and Issatchenkia terricola. Inoculated fermentations yielded a higher amount of alcohol than indigenous ones, indicating the efficiency of selected strains. There was also a greater concentration of higher alcohols, which are usually responsible for the flavor found in alcoholic beverages. Based on the characteristics of the pulp and acceptance in the sensory analysis, gabiroba fruits showed good potential for use in the production of fermented beverage.  相似文献   

13.
Summary The degree of sensitivity of twelve Bifidobacterium (Lactobacillus bifidus) strains to O2 was determined by measuring the size of the inhibition zones obtained when the bacteria were grown in deep agar cultures under air, and by measuring growth in aerated cultures. The size of the inhibition zones varied from 1 to 23 mm. Growth in aerated cultures differed markedly for the strains investigated. No strain grew on agar plates under aerobic conditions.The small inhibition zone of three Bifidobacterium strains might be explained by the presence of a weak catalase activity, which removes traces of H2O2 possibly formed. It is also possible that the NADH oxidase of these strains does not form H2O2 at all. Most probably, the lack of growth on an agar medium results from the fact that these strains only grow below a certain oxidation-reduction potential.One strain, which was rather insensitive to O2, formed a small amount of H2O2 from NADH oxidation. The absence of H2O2 in aerated liquid cultures and cell suspensions of this strain, which lacked catalase and NAD peroxidase activity, must be explained by removal of the traces of H2O2 formed, by an unknown peroxidase system or by a chemical reaction with pyruvate formed during glucose fermentation.For two strains, which were moderately sensitive to O2, accumulation of H2O2 seems to be the principal reason for anaerobiosis. H2O2 turned out to inactivate specifically fructose-6-phosphate phosphoketolase, a key enzyme of the fermentation pathway of bifidobacteria.In the culture medium of two strains, which were extremely sensitive to O2, no H2O2 could be detected after aeration. During anaerobic growth of these strains, the oxidation-reduction potential of the culture decreased so much that neutral red was decolourized. Cell suspensions of these strains only fermented glucose when cysteine was added. It was concluded that these strains required a low oxidation-reduction potential for growth and fermentation.  相似文献   

14.
Heterofermentative lactic acid bacteria (LAB) such as Leuconostoc, Oenococcus, and Lactobacillus strains ferment pentoses by the phosphoketolase pathway. The extra NAD(P)H, which is produced during growth on hexoses, is transferred to acetyl-CoA, yielding ethanol. Ethanol fermentation represents the limiting step in hexose fermentation, therefore, part of the extra NAD(P)H is used to produce erythritol and glycerol. Fructose, pyruvate, citrate, and O2 can be used in addition as external electron acceptors for NAD(P)H reoxidation. Use of the external acceptors increases the growth rate of the bacteria. The bacteria are also able to ferment organic acids like malate, pyruvate, and citrate. Malolactic fermentation generates a proton potential by substrate transport. Pyruvate fermentation sustains growth by pyruvate disproportionation involving pyruvate dehydrogenase. Citrate is fermented in the presence of an additional electron donor to acetate and lactate. Thus, heterofermentative LAB are able to use a variety of unusual fermentation reactions in addition to classical heterofermentation. Most of the reactions are significant for food biotechnology/microbiology.  相似文献   

15.
Culture-based technique was used to study the population dynamics of the bacteria and determine the dominant lactic acid bacteria (LAB) during cassava fermentation. LAB was consistently isolated from the fermented mash with an initial viable count of 6.00 log c.f.u. g−1 observed at 12 h. The aerobic viable count of amylolytic lactic acid bacteria (ALAB) was higher than other group of LAB throughout the fermentation up to 96 h with the highest viable count of 8.08 log c.f.u. g−1. Combination of phenotypic parameters and 16S rDNA gene sequencing identified the dominant group of LAB as Lactobacillus plantarum, L. fermentum and Leuconostoc mesenteroides while the pulse field gel electrophoresis determined that the strains were genotypically heterogeneous. The sugar fermentation profile of the isolates showed that indigestible sugars such as raffinose and stachyose can be fermented by the strains. Information was also generated about the functional properties of the strains. Only strain L. plantarum 9st0 isolate at 0 h of the fermentation produced bacteriocin with antagonism against closely related indicator strains. Quantitatively, the highest amylase activity was produced by strain L. plantarum 7st12, while appreciable amylase was also produced by L. fermentum 1st96. The result of this work showed that selection of mixed starter cultures of bacteriocin- and amylase-producing L. plantarum and L. fermentum will be highly relevant as starter cultures during the intermediate and large scale gari production.  相似文献   

16.
The technological properties of Debaryomyces hansenii (15 strains) and Torulaspora delbrueckii (32 strains) isolated from Greek-style black olives under conditions typical for black olive fermentation were studied. Furthermore, the killer character of the strains was assessed as well as their antimicrobial action against food-borne pathogens. All strains could grow at 15°C and low pH (2.5), whereas the majority of the strains were able to grow at 10% (w/v) NaCl, assimilated d-galacturonic acid, and showed lipolytic activity. Only 33% of D. hansenii and 9% of T. delbrueckii strains could hydrolyse 1% (w/v) oleuropein. A large majority of the strains tolerated 0.3% (w/v) bile salts, which in correlation with acid resistance indicates probiotic potential. Cross-reactions between culture filtrates of D. hansenii and T. delbrueckii and 56 yeast strains isolated during spontaneous Greek-style black olive fermentation were conducted. Focusing on their lytic activity, 17 mycogenic strains were selected. Culture filtrates of the mycogenic strains inhibited strains of L. monocytogenes, B. cereus and S. typhimurium. The active substance was heat resistant (stable after heating at 100°C for 10 min) as well as stable over a pH range from 4.0 to 6.5. The possible inhibition of undesirable yeast contaminants and food-borne pathogens in situ on fermented olives as well as the probiotic potential of strains used as starter adjuncts would contribute to the improvement of quality of the fermented product.  相似文献   

17.
Kôso is a Japanese fermented beverage made with over 20 kinds of vegetables, mushrooms, and sugars. The changes in the bacterial population of kôso during fermentation at 25 °C over a period of 10 days were studied using 454 pyrosequencing of the 16S rRNA gene. The analysis detected 224 operational taxonomic units (OTUs) clustered from 8 DNA samples collected on days 0, 3, 7, and 10 from two fermentation batches. Proteobacteria were the dominant phylum in the starting community, but were replaced by Firmicutes within three days. Seventy-eight genera were identified from the 224 OTUs, in which Bifidobacterium, Leuconostoc, Lactococcus, and Lactobacillus dominated, accounting for over 96% of the total bacterial population after three days’ fermentation. UniFrac–Principal Coordinate Analysis of longitudinal fermented samples revealed dramatic changes in the bacterial community in kôso, resulting in significantly low diversity at the end of fermentation as compared with the complex starting community.  相似文献   

18.
A method for isolating potential probiotic lactobacilli directly from traditional milk-based foods was developed. The novel digestion/enrichment protocol was set up taking care to minimize the protective effect of milk proteins and fats and was validated testing three commercial fermented milks containing well-known probiotic Lactobacillus strains. Only probiotic bacteria claimed in the label were isolated from two out of three commercial fermented milks. The application of the new protocol to 15 raw milk samples and 6 traditional fermented milk samples made it feasible to isolate 11 potential probiotic Lactobacillus strains belonging to Lactobacillus brevis, Lactobacillus fermentum, Lactobacillus gasseri, Lactobacillus johnsonii, Lactobacillus plantarum, Lactobacillus reuteri, and Lactobacillus vaginalis species. Even though further analyses need to ascertain functional properties of these lactobacilli, the novel protocol set-up makes it feasible to isolate quickly potential probiotic strains from traditional milk-based foods reducing the amount of time required by traditional procedures that, in addition, do not allow to isolate microorganisms occurring as sub-dominant populations.  相似文献   

19.
【目的】分析浓香型白酒酒醅发酵过程中氨基甲酸乙酯前体物质瓜氨酸含量显著增加的原因,确定酒醅中能够利用精氨酸并积累瓜氨酸的微生物,为解析白酒中氨基甲酸乙酯的形成机制提供研究基础和理论依据。【方法】采用高通量筛选技术,从浓香型白酒酒醅中分离具有高精氨酸利用能力和高瓜氨酸积累特性的菌株,并通过基因型和表现型验证以及模拟窖内发酵验证它们对瓜氨酸积累的贡献。【结果】共筛选获得20株具有高精氨酸利用能力的菌株,其中Lactococcus garvieae LD3,Bacillus amyloliquefaciens BG5,Pediococcus acidilactici PH7和Staphylococcus pasteuri SH11具有较高的瓜氨酸生成能力,并可使酒醅中瓜氨酸含量显著增加。【结论】筛选获得的4类微生物均能够通过ADI途径代谢积累瓜氨酸,是导致酒醅瓜氨酸含量增加的原因。  相似文献   

20.
The composition of spirits distilled from fermentation of Jerusalem artichoke (Helianthus tuberosus L.) tubers was compared by means of gas chromatography. The microorganisms used in the fermentation processes were the bacterium Zymomonas mobilis, strains 3881 and 3883, the distillery yeast Saccharomyces cerevisiae, strains Bc16a and D2 and the Kluyveromyces fragilis yeast with an active inulinase. The fermentation of mashed tubers was conducted using a single culture of the distillery yeast Saccharomyces cerevisiae and the bacterium Zymomonas mobilis (after acid or enzymatic hydrolysis) as well as Kluyveromyces fragilis (sterilized mashed tubers). The tubers were simultaneously fermented by mixed cultures of the bacterium or the distillery yeast with K. fragilis. The highest ethanol yield was achieved when Z. mobilis 3881 with a yeast demonstrating inulinase activity was applied. The yield reached 94 % of the theoretical value. It was found that the distillates resulting from the fermentation of mixed cultures were characterized by a relatively lower amount of by‐products compared to the distillates resulting from the single species process. Ester production of 0.30–2.93 g/L, responsible for the aromatic quality of the spirits, was noticed when K. fragilis was applied for ethanol fermentation both in a single culture process and also in the mixed fermentation with the bacterium. Yeast applied in this study caused the formation of higher alcohols to concentrations of 7.04 g/L much greater than those obtained with the bacterium. The concentrations of compounds other than ethanol obtained from Jerusalem artichoke mashed tubers, which were fermented by Z. mobilis, were lower than those achieved for yeasts.  相似文献   

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