单一及混合乳酸菌发酵对番木瓜汁品质的影响

目的：探讨植物乳杆菌Lactobacillus plantarum （Lp）、鼠李糖杆菌Lactobacillus rhamnosus （Lr）、嗜酸乳杆菌Lactobacillus acidophilus （La）及两两混合菌（Lp+Lr、Lp+La、Lr+La）对番木瓜汁发酵后植物化学、微生物学、风味特性和功能特性的影响,并开发出一种具有改善功能和促进健康特性的番木瓜益生菌发酵饮料。方法：通过测定发酵过程中pH值、可溶性固形物、可滴定酸、活菌数、葡萄糖、果糖、蔗糖、有机酸和挥发性化合物的变化,考察各菌发酵过程中总酚、总黄酮含量和抗α-葡萄糖苷酶、抗酪氨酸酶的能力。结果：在72 h的发酵过程中,单一菌株培养和混合菌株培养的变化相似,pH值显著降低,酸度显著提高;乳酸和琥珀酸含量均显著提高,柠檬酸和苹果酸含量显著降低。发酵后,木瓜汁中总酚类物质和总黄酮含量均有所增加。Pearson相关分析表明,酚类物质的代谢可能有助于增强α-葡萄糖苷酶和酪氨酸酶的抑制作用。所有发酵组中,由植物乳杆菌单菌发酵的番木瓜汁乳酸、总酚、总黄酮含量最高,对α-葡萄糖苷酶和酪氨酸酶的抑制作用最强。未经发酵的番木瓜原汁中主要检出6种挥发性化合物,丁酸含量最大为89.742%,其次为芳樟醇。发酵后,从6组发酵果汁中共鉴定出25种主要挥发性成分,其中丁酸含量显著降低,减少了番木瓜不愉快气味的产生。所有发酵中,Lp单菌产生的挥发性成分最多（18种）,混合菌Lp+Lr的较少（5种）。虽然混合菌Lp+Lr存在的活菌数最多[7.61 lg（CFU/mL）],但总体看来,单一菌种Lp可能更可取。结论：单菌种植物乳杆菌发酵可以改善番木瓜汁的感官特性,并增强其潜在的功能特性。     

Characterization of Lactobacillus isolates from fermented olives and their bacteriocin gene profiles

Near one hundred isolates of Lactobacillus paraplantarum, Lactobacillus pentosus and Lactobacillus plantarum from table olives were studied. Strains were genotyped by rep-PCR. Although the technique failed to differentiate some isolates at the species level, it proved a robust and easy procedure that could be useful for distinguishing between related strains of L. paraplantarum, L. pentosus and L. plantarum from a large pool of unrelated strains of these species. A PCR-based screening revealed the presence of the plantaricin encoding genes plnA, plnB, plnC, plnD, plnE/F, plnF, plnI, plnJ, plnK, plnG and plnN in most isolates of the three species. Sequences of bacteriocin genes present in L. paraplantarum and L. pentosus were homologous to L. plantarum genes. Through a discriminating analysis of the bacteriocin gene profiles, it was possible to establish a relationship between the origin of isolation and the LAB isolates, regardless of species.     

植物乳杆菌发酵桑葚酵素工艺优化及质量评价

目的:解决新鲜桑葚难以保存的问题,将新鲜桑葚制成桑葚酵素。方法:以新鲜桑葚汁为原料,植物乳杆菌为生产菌种,总酚含量为评价指标,通过单因素试验结合响应面试验优化了植物乳杆菌桑葚酵素的发酵工艺,并对桑葚酵素的理化、微生物及感官质量指标进行评价。结果:优化后发酵工艺条件为发酵时间40 h、发酵温度32℃、接种量25%,所制得的植物乳杆菌桑葚酵素的总酚含量达(43.48±0.67)μg/mL,是未经发酵的桑葚汁的1.62倍,可溶性固体物含量为5.36%,pH值为4.08±0.01,微生物指标满足国家标准;桑葚酵素呈紫红、色泽均匀,具有浓郁的桑葚果香和发酵的香味、无异味,酸味柔和、风味好,有光泽、无杂质及沉淀。结论:经植物乳杆菌发酵制得桑葚酵素的过程有生物活性物质产生,有利于提高桑葚酵素质量。     

植物乳杆菌发酵提取未成熟琯溪蜜柚果实果胶工艺优化

目的:利用植物乳杆菌发酵未成熟琯溪蜜柚果实提取果胶,并分析植物乳杆菌发酵提取果胶的性质。方法:以果胶提取率为指标,采用正交试验优化植物乳杆菌发酵未成熟琯溪蜜柚果实提取果胶的工艺条件,并测定果胶的半乳糖醛酸含量、酯化度、蛋白质、持水性、持油性、乳化活性以及乳化稳定性。结果:植物乳杆菌发酵未成熟琯溪蜜柚果实提取果胶的最佳工艺条件为发酵温度37℃、植物乳杆菌发酵接种量14%、液料比25∶1 (mL/g)、发酵时间12 h。此条件下未成熟琯溪蜜柚果胶提取率为11.60%;果胶的半乳糖醛酸含量、酯化度、蛋白质、持水性、持油性、乳化活性以及乳化稳定性分别为26.13%、68.58%、1.57%、0.53 g/g、7.01 g/g、14.33%和33%。结论:植物乳杆菌发酵提取的果胶提取率与酸法工艺的相似,所得果胶为高酯化度果胶,且应用性质良好。     

植物乳杆菌脂磷壁酸对小鼠肠炎的作用及其机制

为了明确植物乳杆菌脂磷壁酸对肠炎的作用,提取了益生性植物乳杆菌GSLP-7的脂磷壁酸 (lipoteichoic acid, LTA),灌胃肠炎小鼠,检测小鼠肠道组织损伤、血清炎症因子、髓过氧化物酶(myeloperoxidase, MPO)和抗氧化物活性、粪便中短链脂肪酸的含量以及免疫信号通路相关蛋白表达水平的变化,结果显示,脂磷壁酸能有效缓解肠道炎症,效果优于益生菌菌体GSLP-7。与肠炎小鼠相比,脂磷壁酸干预能够显著减轻小鼠结肠组织病理学损伤,结肠萎缩减少12.38%;血清中促炎相关细胞因子TNF-α、IL-1β、IL-6、IL-12含量分别降低了34.97%、52.47%、38.59%、34.30%,抗炎相关细胞因子IL-10的含量增加了24.78%(P<0.05);结肠组织的MPO和血清中的MPO活性、一氧化氮(NO)和丙二醛(malondialdehyde, MDA)的含量分别降低了27.93%、23.84%、29.60%、35.32%,总超氧化物歧化酶(total superoxide dismutase,T-SOD)和谷胱甘肽(glutathione,GSH)活性增加了56.86%、39.74%;肠道短链脂肪酸总量提高了3.92倍,表明脂磷壁酸干预后肠道炎症缓解(P<0.05)。差异表达蛋白的Western-blot检测显示,抑制肠上皮细胞TLR4, MyD88和MAPK关键蛋白的表达,阻断TLR4-MyD88-MAPK和NF-κB信号通路,是脂磷壁酸缓解肠炎的可能机制。     

Bacteriocinogenic Lactobacillus plantarum ST16Pa isolated from papaya (Carica papaya) — From isolation to application: Characterization of a bacteriocin

Strain ST16PA, isolated from papaya was identified as Lactobacillus plantarum based on biochemical tests, PCR with species-specific primers and 16S rDNA sequencing. L. plantarum ST16PA produces a 6.5 kDa bacteriocin, active against different species from genera Enterobacter, Enterococcus, Lactobacillus, Pseudomonas, Streptococcus and Staphylococcus and different serotypes of Listeria spp. The peptide is inactivated by proteolytic enzymes, but not when treated with ??-amylase, catalase, lipase, Triton X-100, SDS, Tween 20, Tween 80, urea, NaCl and EDTA. However, presence of 1% Triton X-114 deactivates the bacteriocin. No change in activity was recorded after 2 h at pH values between 2.0 and 12.0, and after treatment at 100 °C for 120 min or 121 °C for 20 min. The mode of activity against Lactobacillus sakei ATCC 15521, Enterococcus faecalis ATCC 19443 and Listeria innocua 2030C was bactericidal, resulting in cell lysis and enzyme-leakage. No significant differences in cell growth and bacteriocin production were observed when strain ST16Pa was cultured in MRS broth at 26 °C and 30 °C for 24 h (25 600 AU/ml). However, even though strain ST16PA grows well in MRS broth at 15 °C and 37 °C, a reduction of bacteriocin production was observed (400 AU/ml and 1600 AU/ml, respectively). In addition, effect of MRS medium components, different initial pH and additions of glycerol or vitamins to the media on bacteriocin ST16Pa production was studied.Peptide ST16PA adsorbs (400 AU/ml) to producer cells. However, bacteriocin ST16Pa was adsorbed at 50% to cells of L. innocua 2030C and at 75% to L. sakei ATCC 15521 and E. faecalis ATCC 19433 when experiments were conducted at 30 °C and pH 6.5. Adsorption of bacteriocin ST16Pa to target cells at different temperatures, pH and in presence of potassium sorbate, sodium nitrate, sodium chloride, ascorbic acid, Tween 80 and Tween 20 were also studied. To the best of our knowledge, this is the first report on detection of L. plantarum in papaya.     

Pediocin PA-1 and a pediocin producing Lactobacillus plantarum strain do not change the HMA rat microbiota

The bacteriocin pediocin PA-1 has potential use as a food biopreservative, and understanding its effect on the commensal gut microbiota is important for assessment of consumer risks associated with the use of biopreservative cultures. Effects of ingested (i) pediocin PA-1 producing Lactobacillus plantarum DDEN 11007, (ii) the plasmid cured pediocin negative L. plantarum DDEN 12305, or (iii) supernatants of either of these two strains on the composition of the intestinal microbiota of Human Microbiota Associated (HMA) rats were examined by selective cultivation and molecular methods. The culturable microbiota was in all treatments dominated by lactic acid bacteria and coliforms and no changes in the rat commensal microbiota were detected after ingestion of either of the two L. plantarum strains as determined by both culturable methods and molecular methods (DGGE). Both strains were detected in the faeces after ingestion. Pediocin PA-1 did not mediate changes of the rat microbiota, and a biological assay indicated that the bacteriocin was degraded or inactivated during passage through the intestine.     

Effect of a single oral administration of Lactobacillus plantarum DSMZ 8862/8866 before and at the time point of weaning on intestinal microbial communities in piglets

The aim of this study was to evaluate whether a single administration of two strains of Lactobacillus plantarum (DSMZ 8862 and 8866) either before or at the time point of weaning can influence the intestinal microbiota of piglets. A total of 176 piglets were allocated into five groups: control (LP0), administration of 5 × 10⁹ or 5 × 10¹⁰ cfu at day 25 of life (LP1, LP2) and administration of 5 × 10⁹ or 5 × 10¹⁰ cfu at day 28 of life (LP3, LP4). Piglets were weaned on day 28 of life. On day 25 (LP1, LP2), 28 (LP0, LP3, LP4), 33 (all groups) and 39 (all groups) of life, 10–13 animals of each group were killed and genomic DNA was extracted from small and large intestinal contents. Denaturing gradient gel electrophoresis demonstrated that administration of L. plantarum had a significant effect in GIT microbial communities as revealed by the Simpson's index of diversity and cluster analysis based on the Dice similarity index; this effect was more pronounced in groups LP3 and LP4. A treatment dependent presence of Clostridium glycolicum-like, Lactobacillus sobrius-like, Eubacterium rectale-like and Roseburia faecalis-like phylotypes was observed. The results show that the administration of L. plantarum at the point of weaning can influence gastrointestinal microbiota in weaning piglets which may have positive results on gastrointestinal health.     

The effect of Lactobacillus buchneri and Lactobacillus plantarum on the fermentation, aerobic stability, and ruminal degradability of low dry matter corn and sorghum silages

The effect of Lactobacillus buchneri, alone or in combination with Lactobacillus plantarum, on the fermentation, aerobic stability, and ruminal degradability of low dry matter corn and sorghum silages was studied under laboratory conditions. The inoculants were applied at 1 x 10(6) cfu/g. Silages with no additives served as control. After treatment, the chopped forages were ensiled in 1.5-L anaerobic jars. Three jars per treatment were sampled on d 2, 4, 8, 15, and 90. After 90 d of storage, the silages were subjected to an aerobic stability test lasting 5 d, in which CO2 production, as well as chemical and microbiological parameters, was measured to determine the extent of aerobic deterioration. At the end of the ensiling period (d 90), the L. buchneri- and L. buchneri + L. plantarum-inoculated silages had significantly higher levels of acetic acid than the control and L. plantarum-inoculated silages. Therefore, yeast activity was impaired in the L. buchneri- and L. buchneri + L. plantarum-inoculated silages. As a result, L. buchneri, alone or in combination with L. plantarum, improved aerobic stability of the low dry matter corn and sorghum silages. The combination of L. buchneri and L. plantarum reduced ammonia N concentrations and fermentation losses in the silages compared with L. buchneri alone. However, L. buchneri, L. plantarum, and a combination of L. buchneri + L. plantarum did not effect in situ rumen dry matter, organic matters, or neutral detergent fiber degradability of the silages. The L. buchneri was very effective in protecting the low dry matter corn and sorghum silages exposed to air under laboratory conditions. The use of L. buchneri, alone or in combination with L. plantarum, as a silage inoculant can improve the aerobic stability of low dry matter corn and sorghum silages by inhibition of yeast activity.     

Diversity of stress tolerance in Lactobacillus plantarum, Lactobacillus pentosus and Lactobacillus paraplantarum: A multivariate screening study

Sixty-three strains of the taxonomically related species Lactobacillus plantarum subsp. plantarum, L. plantarum subsp. argentoratensis, L. paraplantarum and L. pentosus isolated from sourdoughs and other food and non-food sources and 14 strains of other members of the genus Lactobacillus were screened for their tolerance of acid, alkaline, heat, oxidative, osmotic, detergent and starvation stresses in order to evaluate the diversity of stress response. Most strains of the L. plantarum group were highly tolerant of acid, alkaline and osmotic stress and highly sensitive to detergent stress, while a larger diversity was found for other stress. Multivariate analysis allowed grouping the strains in clusters with similar response patterns. Stress response patterns in the L. plantarum group were similar to those of species of the L. casei/L. paracasei group but clearly different from those of other mesophilic Lactobacillus. No relationship was found between grouping obtained on the basis of stress response patterns and by genotypic fingerprinting (rep-PCR), nor with the taxonomic position or isolation source of the strains. Further experiments with selected strains showed that exponential phase cells were generally but not always more sensitive than stationary phase cells. The ability to grow under stressful conditions showed a slightly better correlation with the ecological conditions prevailing in the isolation niches of the strains.This study will be the basis for further investigations to identify and exploit the basis of diversity in the stress response of lactic acid bacteria.     

耐热型植物乳杆菌微胶囊粉剂

目的:提高植物乳杆菌的耐热性。方法:在前期研究的微胶囊乳液中加入2-羟丙基-β-环糊精(2-HP-β-CD),通过喷雾干燥法制备植物乳杆菌微胶囊粉剂。通过响应面法,对不同参数进行优化。采用光学显微镜、电子显微镜对其形态进行观察,通过激光粒度分析仪及Zeta电位分析仪测定其粒径电位,利用分光光度计测定其吸光度变化,并采用烘箱加热的方式进行耐热性试验。结果:随2-HP-β-CD与乳液质量比、进料速率、进风温度、进风速率增加,存活率呈先升后降的趋势(P<0.05);在2-HP-β-CD与乳液质量比为3.13、进料速率为288 mL/h、进风速率为112 m³/h、进风温度为118℃时,菌体存活率为(99.53±0.11)%,载菌量为1.64×10⁹ CFU/g;扫描电镜和显微结果显示微胶囊为中心凹陷的微粒,在水中呈球形分散,菌体聚集于内部,其水分散液吸光值1 h内变化不显著,Z-平均粒径为472.7 nm且粒径分布较集中,Zeta电位为-40.37 mV;微胶囊在130℃处理60 s,存活率为96.79%,与菌泥差异极其显著(P<0.0...     

Production of salami from beef, horse, mutton, Blesbok (Damaliscus dorcas phillipsi) and Springbok (Antidorcas marsupialis) with bacteriocinogenic strains of Lactobacillus plantarum and Lactobacillus curvatus

Lactobacillus plantarum 423, producer of bacteriocin 423, Lactobacillus curvatus DF38, producer of curvacin DF38, and a bacteriocin-negative mutant of L. plantarum 423 (423m) were evaluated as starter cultures in the production of salami from beef, horse, mutton, Blesbok (Damaliscus dorcas phillipsi) and Springbok (Antidorcas marsupialis). Growth of L. plantarum 423 and L. curvatus DF38 was best supported in Blesbok salami, as revealed by the highest growth rate during sweating, cold smoking and maturation, and final cell numbers after 70 days (1 × 10⁸ and 5 × 10⁷ cfu/g, respectively). Growth of Listeria innocua was the best suppressed in Blesbok salami fermented with L. plantarum 423 and L. curvatus DF38. Growth of L. innocua in horse salami was best suppressed when fermented with L. curvatus DF38. The final pH of salami fermented with L. plantarum 423 and L. plantarum 423m was slightly lower (4.4) compared to the pH of salami produced with L. curvatus DF38 (pH 4.7). No significant differences (P > 0.05) were recorded by a trained sensory taste panel amongst the three starter cultures regarding colour and venison like aroma. Horse, Blesbok and Springbok salami were rated significantly higher (P ? 0.05) in salami flavour than mutton salami, which was rated the lowest for this attribute. Blesbok salami was rated the highest for sour meat aroma, while beef salami was rated the lowest. Springbok salami was rated the highest in terms of oily mouth feel. Beef salami had the most compact structure and horse salami the softest structure of all meat types fermented. In general, salami produced with L. plantarum 423 yielded the best sour meat aroma, colour, texture, venison like flavour, sour meat flavour and oily mouthfeel and is considered superior to the L. plantarum mutant (strain 423m) and L. curvatus DF38.     

Effects of different probiotic strains of Lactobacillus and Bifidobacterium on bacterial translocation and liver injury in an acute liver injury model

Septic complications represent frequent causes of morbidity in liver diseases and following hepatic operations. Most infections are caused by the individual own intestinal microflora. The intestinal microflora composition is important in physiological and pathophysiological processes in the human gastrointestinal tract, but their influence on liver in different situations is unclear. We therefore studied the effect of different Lactobacillus strains and a Bifidobacterium strain on the extent of liver injury, bacterial translocation and intestinal microflora in an acute liver injury model.Sprague–Dawley rats were divided into five groups: acute liver injury control, acute liver injury+B. animalis NM2, acute liver injury+L. acidophilus NM1, acute liver injury+L. rhamnosus ATCC 53103, and acute liver injury+L. rhamnosus DSM 6594 and L. plantarum DSM 9843. The bacteria were administered rectally daily for 8 days. Liver injury was induced on the 8th day by intraperitoneal injection of -galactosamine (1.1 g/kg BW). Samples were collected 24 h after the liver injury. Liver enzymes and bilirubin serum levels, bacterial translocation (to arterial and portal blood, liver and mesenteric lymph nodes (MLNs)), and intestinal microflora were evaluated.L. acidophilus NM1; L. rhamnosus ATCC 53103, and L. rhamnosus DSM 6594+L. plantarum DSM 9843 decreased bacterial translocation compared to the liver injury control group. B. animalis NM2 increased bacterial translocation to the mesenteric lymph nodes. The levels of alanine aminotransferase (ALAT) were significantly lower in the L. acidophilus, L. rhamnosus ATCC 53103, L. rhamnosus DSM 6594+L. plantarum DSM 9843 groups compared to the liver injury group. The L. rhamnosus and L. rhamnosus+L. plantarum groups significantly reduced ALAT levels compared to the B. animalis group. All administered bacteria decreased the Enterobacteriaceae count in the cecum and colon.Administration of different lactobacilli and a Bifidobacterium strain in an acute liver injury rat model, has shown different effects on bacterial translocation and hepatocellular damage. L. acidophilus, L. rhamnosus, and L. rhamnosus+L. plantarum reduced bacterial translocation and hepatocellular damage. B. animalis NM2 increased bacterial translocation to the mesenteric lymph nodes and did not affect hepatocellular damage.     

Technological and probiotic role of adjunct cultures of non-starter lactobacilli in soft cheeses

The influence of two cheese-isolated Lactobacillus strains on cheese composition, acceptability and probiotic capacity was assessed. Soft cheeses with and without the addition of Lactobacillus plantarum I91 or Lactobacillus paracasei I90 were prepared. Gross composition was assessed and secondary proteolysis was described by soluble fractions and free amino acids profiles. Acceptability was determined by a panel of 98 non-trained consumers. Cheeses harboring added Lactobacillus strains were also studied in vivo to evaluate their probiotic capacity. Gross composition of the cheeses was similar for control and treated (Lactobacillus-added) cheeses. Peptidolysis increased in cheeses with added lactobacilli, which was evidenced by a higher free amino acid content. Overall, the acceptability of the cheeses was good: 65%–80% of the consumers said that they “liked very much” or “liked” the cheeses. Cheeses with L. plantarum I91 showed the highest changes in composition and proteolysis and were the most accepted ones. On the contrary, composition of cheeses with L. paracasei I90 was similar to that of the controls, but these samples were less accepted than cheeses without lactobacilli. The oral administration of cheese containing L. plantarum I91 or L. paracasei I90 proved to be safe and able to enhance the number of IgA + cells in the small intestine lamina propria of mice. The use of selected strains of NSLAB exerted a technological and probiotic role: it contributed to the standardization of cheese quality and induced benefic health effects at the gut mucosa in vivo.     

Effect of microencapsulation on survival of Lactobacillus plantarum in simulated gastrointestinal conditions, refrigeration, and yogurt

In the present research the survival of free and microencapsulated cells of a new strain of Lactobacillus plantarum BL011 under stress conditions was tested in sodium alginate or pectin, coated with sodium alginate or chitosan. Results for the simulated gastrointestinal medium (SGT) showed no change in viability of cells in relation to the control. However, the simulated gastric medium (GM) drastically reduced the viability under the tested conditions, with no significant differences between free and immobilized cells. Under refrigerated storage viability of immobilized cells were greatly enhanced compared to the free microorganisms, and the treatments showing the lowest loss of viability were those of 4% (w/v) pectin, 3% (w/v) sodium alginate coated with chitosan and a mixture of 2% (w/v) sodium alginate and 2% (w/v) pectin, respectively. Loss of viability of immobilized L. plantarum in 3% alginate coated with chitosan in yogurt was of 0.55 log cycles during 38 days of storage. The results of this study suggest the efficiency of immobilization techniques to increase the survival of lactobacilli in yogurt under refrigerated storage.     

Effect of Lactobacillus plantarum and chitosan in the reduction of browning of pericarp Rambutan (Nephelium lappaceum)

The effects of Lactobacillus plantarum alone or in combination with chitosan were evaluated on quality and color retention in rambutan fruits (Nephelium lappaceum) stored at 25 °C and 10 °C with 75 ± 2.5% of relative humidity for 10 and 15 days, respectively. The development of the microorganisms was evidenced by viability analyses and lactic acid production. The application of L. plantarum significantly improved color retention (a* and L*), and reduced weight losses. The lactobacilli, alone or in combination with chitosan, preserved fruit quality characteristics such as firmness, total soluble solids and titratable acidity. The lactobacilli application on rambutan pericarp produced acidification of pericarp and avoided the browning; thereby desiccation was prevented due to biofilm formation.     

Influence of fruit ripeness and salt concentration on the microbial processing of Arbequina table olives

Arbequina table olives are processed as “naturally green olives”, they are directly placed in brine and fermentation starts spontaneously. Olives are harvested just before they change to ‘turning colour’. Different salt concentrations are used depending on the producer. The aim of the study was to evaluate how (i) the ripeness of the olive when it is harvested and (ii) the salt concentration of the brine influence the different microorganism populations in brine during the fermentation of Arbequina table olives.The results showed that the Enterobacteriaceae population lasted longer in black and turning colour olives than in green olives, whereas the growth of lactic acid bacteria was delayed in green olives. A higher salt concentration favoured the elimination of Enterobacteriaceae and hindered yeast growth. The main yeast species identified were Pichia anomala, Candida sorbosa and Candida boidinii, while Lactobacillus plantarum was the only lactic acid bacteria species involved in the process. In a sensory test, panellists preferred green olives and were not able to tell the laboratory-scale processed olives from a commercial sample, nor could they distinguish green olives from different brines.     

Binding of mutagens to exopolysaccharide produced by Lactobacillus plantarum mutant strain 301102S

Exopolysaccharide (EPS) was produced by Lactobacillus plantarum 301102 on exposure to the mutagenic action of acridine orange and novobiocin. The biological characteristics of this mutant strain 301102S were the same as those of the parent strain, but fermented milk prepared with the mutant strain showed antimutagenic activity on 3-amino-1,4-dimethyl-5H-pyrido indole. Only EPS-bound cells of strain 301102S showed binding ability to mutagens such as heterocyclic amines, and the mutagens were inactivated by binding to EPS. The binding ability was affected by pH; the greatest percentage binding was noted at pH 8.0. Addition of Mg²⁺ and sodium dodecyl sulfate, but not oxgall, inhibited the binding ability. Therefore, the binding mechanism of the EPS may consist of ion-exchange and hydrophobic bonds, and the EPS would bind mutagens in the intestine.     

不同来源的植物乳杆菌基因组和抗生素抗性

为了研究不同分离源对植物乳杆菌基因组和功能的影响,选取了来自发酵酱、泡菜、粪便3种环境的33株植物乳杆菌,通过比较基因组学手段研究菌株的基因组基本特征、直系同源基因、系统进化关系,并结合功能基因注释结果与表型结果分析菌株对抗生素的耐药性。系统发育树揭示了分离源对植物乳杆菌的遗传进化具有较为显著的影响;同源基因结果表明粪便源的菌株其特殊基因数量要高于泡菜源和发酵酱源菌株的数量。33株植物乳杆菌均含有环丙沙星、四环素、氯霉素、甲氧苄氨嘧啶和万古霉素的抗性基因,菌株对这些抗生素也表现出抗性;绝大多数菌株对庆大霉素、链霉素、卡那霉素、新霉素、氨苄西林敏感,在基因组中也没有相关抗性基因;而红霉素和克林霉素的基因和表型并不对应。抗生素实验结果说明,分离源对菌株影响较小,大部分基因型与表型可以对应,基因组学对研究植物乳杆菌的生理特性起一定的指导作用。     

Coculture-inducible bacteriocin activity of Lactobacillus plantarum strain J23 isolated from grape must

Detection and characterization of bacteriocin production by Lactobacillus plantarum strain J23, recovered from a grape must sample in Spain, have been carried out. Bacteriocin activity was degraded by proteolytic enzymes (trypsin, alfa-chymotrypsin, papaine, protease, proteinase K and acid proteases), and it was stable at high temperatures (121 degrees C, 20min), in a wide range of pH (1-12), and after treatment with organic solvents. L. plantarum J23 showed antimicrobial activity against Oenococcus oeni, and a range of Lactobacillus and Pediococcus species. Bacteriocin production was detected in liquid media only when J23 was cocultivated with some inducing bacteria, and induction took place when intact cells or 55 degrees C heated cells of the inducer were cocultivated with J23, but not with their autoclaved cells. Bacteriocin activity of J23 was not induced by high initial J23 inocula, and it was detected in cocultures during the exponential phase. The presence of ethanol or acidic pH in the media reduced bacteriocin production in the cocultures of J23 with the inducing bacteria. The presence of plantaricin-related plnEF and plnJ genes was detected by PCR and sequencing. Nevertheless, negative results were obtained for plnA, plnK, plNC8, plS and plW genes.