Effect of Lactobacillus plantarum on germination and growth of tomato seedlings

Significant stimulation of germination of tomatoes (Lycopersicon esculentum Mill. cv Odessa plum) with poor initial germination capacity was achieved by soaking their seeds during 6 h in suspensions of nine out of ten Lactobacillus plantarum strains tested. The increase in percentage of germination ranged from 15.1 to 7.6 %. Lengths of shoots, main and lateral roots and development of root hairs increased after inoculation of seeds with studied L. plantarum strains. The treatments of seeds with L. plantarum expanded shoot lengths by 16.4–18.2 %. Stimulation of main root lengths in the tested tomato seedlings varied from 10.5 to 31.4 %, and the stimulation of lateral roots from 28.6 to 32.2 %. Lactobacilli from different strains exert different effects on the seedlings: for instance, inoculation with certain strains resulted in the stimulation of the main root growth and the inoculation with another strain stimulated shoot growth or growth of the lateral roots. It is the first report about plant-stimulating activities of L. plantarum from different ecological niches (plant surfaces, surfaces of edible mushrooms, dairy products) in the absence of nutritional compounds.     

Protective effect of betaine on survival of Lactobacillus plantarum subjected to drying

Abstract The aim of this study was to investigate the effect of betaine on survival of Lactobacillus plantarum subjected to drying. A defined medium was devised devoid of betaine. Addition of 2 mM betaine to this medium increased the growth rate of cells grown under osmotic stress and also made the organism more tolerant. Cells cultivated under osmotic stress of 0.6 M sodium chloride and in the presence of betaine showed an increased survival after air drying and subsequent vacuum desiccation to a water activity of 0.12.     

植物乳杆菌发酵、冻干工艺及其益生特性的研究

目的 以Lactobacillus plantarum SQ-2506为目标,研究该菌株的发酵、冻干工艺及其益生特性。方法 通过对培养基中C源、N源和刺激因子的浓度改变考察对活菌数的影响,从而确定培养基的最佳配方;在确定最佳培养基后做出该菌的生长曲线以确定最佳发酵时间点;同时考察冻干保护剂的配方和预冷时间对菌粉活菌数的影响;此外,对植物乳杆菌进行产酸、产H2O2、生物膜形成能力、抑菌特性以及抗氧化能力的检测。结果 最佳MRS培养基中葡萄糖浓度为0.8%、酪蛋白胨为0.4%、牛肉粉为0.6%、吐温为0.06%;植物乳杆菌的生长曲线在5 h时达到稳定期,此时发酵液活菌数为3.16×109 CFU/mL,发酵液的pH为4.45。最佳冻干保护剂的配方：脱脂乳100 g/L,蔗糖120 g/L,抗坏血酸20 g/L,谷氨酸钠30 g/L;冻干前对上机液预冻时间为2 h,此时菌粉冻干存活率为70.21%。该菌株具有产酸、产H2O 2能力,并对大肠埃希菌、金黄色葡萄球菌和白色假丝酵母均有一定的抑制作用,形成膜能力较强,且具有一定的抗氧化能力。结论 通过培养基成分、发酵条件和冻干工艺的优化以及对其益生特性的研究,为下一步新药开发和规模化生产奠定基础。     

Measuring and modelling the glucose-fermenting activity of Lactobacillus plantarum

Summary The pH decrease in a phosphate buffer due to fermentation of glucose to lactic acid by non-growing Lactobacillus plantarum cells has been studied. The method used offers a quick and reproducible way of measuring the glucose-fermenting activity of L. plantarum. The maximum observed velocity of pH decrease is linear with the biomass concentration and is defined as the activity of the cell suspension. With L. plantarum, recalculation of this arbitrary unit (pH·min^–1 per gram dry weight) to a conceivable unit of lactic acid production rate (mol·min^–1 per gram dry weight) is possible. This recalculation is based on the titration theory of a weak base with a weak acid. The same theory together with the lactic acid production kinetics of L. plantarum is applied to model the entire pH-time curve.Offprint requests to: L. C. Lievense     

Development of a minimal growth medium for Lactobacillus plantarum

Aim:  A medium with minimal requirements for the growth of Lactobacillus plantarum WCFS was developed. The composition of the minimal medium was compared to a genome-scale metabolic model of L. plantarum .
Methods and Results:  By repetitive single omission experiments, two minimal media were developed: PMM5 (true minimal medium) and PMM7 [a pseudominimal medium, supporting proper biomass formation of 350 mg l⁻¹ dry weight (DW)]. The specific growth rate of L. plantarum on PMM7 was found to be 50% and 63% lower when compared to growth on established growth media (chemically defined medium and MRS, respectively). Using a genome-scale metabolic model of L. plantarum , it was predicted that PMM5 and PMM7 would not support the growth of L. plantarum . This is because the biosynthesis of para- aminobenzoic acid ( p ABA) was predicted to be essential for growth. The discrepancy in simulated growth and experimental growth on PMM7 was further investigated for p ABA; a molecule which plays an important role in folate production. The growth performance and folate production were determined on PMM7 in the presence and absence of p ABA. It was found that a 12 000-fold reduction in folate pools exerted no influence on formation of biomass or growth rate of L. plantarum cultures when grown in the absence of p ABA.
Conclusion:  Largely reduced folate production pools do not have an effect on the growth of L. plantarum , showing that L. plantarum makes folate in a large excess.
Significance and Impact of the study:  These experiments illustrate the importance of combining genome-scale metabolic models with growth experiments on minimal media.     

1株植物乳杆菌的抑菌作用及其生物学特性的研究

植物乳杆菌（Lactobacillus plantarum）是乳酸杆菌中的一种,常存在于发酵的蔬菜和果汁中。植物乳杆菌作为人体肠道的益生菌群,具有维持肠道菌群平衡、提高机体免疫力和促进营养物质吸收等多种作用。研究从市售腌渍蔬菜中分离筛选获得一株植物乳杆菌,以9种菌作为指示菌,采用牛津杯琼脂扩散法检测筛选菌株的抑菌谱大小。结果表明,该菌株能较强的抑制大肠杆菌、柠檬色葡萄球菌、藤黄微球菌和枯草芽孢杆菌等指示菌。此外,研究了菌株对温度的稳定性,p H值的耐受性及其酶的敏感性等生物学特性,结果显示该株植物乳杆菌菌株具有良好的热稳定性,酸碱稳定性,并且对3种蛋白酶具有很好的敏感性。这为今后深入研究与开发植物乳杆菌奠定了基础。     

Influence of pH and initial lactate concentration on the growth of Lactobacillus plantarum

Summary Fermentation yields of Lactobacillus plantarum were measured at controlled pH between 4.0 and 8.0 and initial lactate concentrations of 0–90 g/l. Optimal growth conditions at pH 6.0 without addition of lactate gave a growth rate of 0.57 h^–1 and 20 g dry biomass/mol ATP formed (Y _ATP). The pH variations resulted in a decrease in growth rate but the effect on Y _ATPwas insignificant. The addition of lactate to the medium at 0 h resulted in linear decrease in the growth rate of the culture, and all the metabolic activities were completely inhibited at 110 g/l. The Y _ATPand biomass/ substrate yield (Y _X/S) remained fairly steady up to 33 g lactate/l, beyond which both yields decreased considerably. Offsprint requests to: M. Raimbault     

Effect of carnitines on Lactobacillus plantarum subjected to osmotic stress

We investigated the effect of carnitine analogues on the physiology of Lactobacillus plantarum subjected to salt stress. Salt stressed cells of L. plantarum accumulated exogenously provided carnitine and its structural analogues acetylcarnitine and propionylcarnitine to maximum concentrations of 466, 122 and 75 μmol (g dry weight of cells)⁻¹, respectively. Addition of these carnitines to osmotically stressed medium increased growth rate. Furthermore, the intracellular amino acid pool, consisting of mainly aspartate and glutamate, was reduced when carnitine, acetylcarnitine or propionylcarnitine were included in the medium. This is the first study demonstrating a role for β-substituted acylcarnitine esters in osmoadaptation of a lactic acid bacterium.     

Modeling the specific growth rate of Lactobacillus plantarum in cucumber extract

Extensive empirical research has been published on the fermentation of vegetables, but little predictive modeling of the process is available. The objectives of this study were to assess the effects of key variables involved in cucumber fermentation and to develop models for predicting the growth of Lactobacillus plantarum in pure and mixed culture fermentations. The growth medium for the studies was cucumber juice. The effects of various concentrations of lactic, acetic, and hydochloric acids and sodium chloride on growth at 30° C were determined in batch culture. Limiting conditions for growth were pH 3.37 (lower limit), 69 mm undissociated lactic acid, 150 mm undissociated acetic acid, or 11.8% NaCl. Acetic acid was stimulatory to growth at low concentrations (up to 40 mm) but inhibitory at higher concentrations. Lactic acid was more inhibitory than acetic acid, whether total or undissociated concentrations were used as the basis of comparison. A predictive equation for specific growth rate was developed, tested, and shown to predict growth of L. plantarum in batch processes reasonably well.Mention of a trademark or proprietary product does not constitute a guarantee or warranty of the product by the U. S. Department of Agriculture or North Carolina Agricultural Research Service, nor does it imply approval to the exclusion of other products that may be suitable Correspondence to: H. P. Fleming     

Effect of inactivation of ccpA and aerobic growth in Lactobacillus plantarum: A proteomic perspective

Lactobacillus plantarum is a facultative heterofermentative lactic acid bacterium widely used in the production of most fermented food due to its ability to thrive in several environmental niches, including the human gut. In order to cope with different growth conditions, it has developed complex molecular response mechanisms, characterized by the induction of a large set of proteins mainly regulated by HrcA and CtsR repressors as well as by global regulators such as carbon catabolite control protein A (CcpA). In this study, the role of CcpA in the regulation of growth under anaerobiosis and aerobiosis, and the adaptation to aeration in L. plantarum WCFS1 were comprehensively investigated by differential proteomics. The inactivation of ccpA, in both growth conditions, significantly changed the expression level of 76 proteins, mainly associated with carbohydrate and energy metabolism, membrane transport, nucleotide metabolism, protein biosynthesis and folding. The role of CcpA as pleiotropic regulator was particularly evident at the shift from homolactic fermentation to mixed fermentation. Proteomic results also indicated that the mutant strain was more responsive to aerobic growth condition.     

Effects of phenolic compounds on the growth and the fatty acid composition of Lactobacillus plantarum

The effects of different phenolic compound concentrations on the fatty acid composition of Lactobacillus plantarum isolated from traditional home-made olive brines were determined. Increasing amounts of caffeic and ferulic acids induced a gradual increase in the amounts of myristic, palmitoleic, stearic and 9,10-methylenehexadecanoic (C17Δ, where Δ represents the cyclopropane group) acid with a concomitant decrease of lactobacillic acid (C₁₉Δ). On the other hand, the addition of tannins induced an increase in the C₁₉Δ level at the expense of vaccenic acid content. The presence of acidic phenols and tannins also affected bacterial growth, inducing the most obvious effect with tannin at 1 g l⁻¹. Received: 1 July 1997 / Received revision: 9 September 1997 / Accepted: 15 September 1997     

Lactobacillus plantarum phytase activity is due to non-specific acid phosphatase

Microbial phytases suitable for food fermentations could be obtained from lactic acid bacteria isolated from natural vegetable fermentations. Phytase activity was evaluated for six lactic acid bacteria cultures. Although the highest activity was found for Lactobacillus plantarum, the phytase activity was very low. Further characterization of the enzyme with phytate-degrading activity showed a molecular weight of 52 kDa and an optimum activity at pH 5.5 and 65 degrees C. Enzyme activity was due to a non-specific acid phosphatase which had a higher hydrolysis rate with monophosphorylated compounds such as acetyl phosphate that could explain the low phytase activity.     

Effect of l-malate,d-glucose and l-lactate on malolactic fermentation and growth of Lactobacillus plantarum and Lactobacillus curvatus wild strains isolated from wine

l-Malate fermentative rate in Lactobacillus plantarum and Lactobacillus curvatus was improved when l-malate was over 0.1% but decreased when exogenous d-glucose raised over 0.3% or in the presence of exogenous l-lactate. Significant increases in the growth were observed in the presence of exogenous d-glucose. l-malate residual concentrations were in all cases below 1%.     

Optimising single cell activity assessment of Lactobacillus plantarum by fluorescent in situ hybridisation as affected by growth

Fluorescent in situ hybridisation (FISH) with a 16S ribosomal RNA (rRNA)-targeted oligonucleotide probe, Eub338, could be used to estimate the in situ activity of Lactobacillus plantarum WCFS1 in exponentially growing cells. However, L. plantarum is capable of growth to very high cell densities, and the properties of the L. plantarum cell envelope prevented effective entry of the fluorescent oligonucleotide probe into the cells at later stages of growth at high cell densities. Total rRNA measurements of cells isolated at different growth stages showed maximal amounts of RNA (8.77+/-0.8 fg) per cell at the early stationary phase and confirmed the effectiveness of FISH for accurate activity measurement in exponentially growing cells.     

猪表皮生长因子在植物乳杆菌中的表达及其活性检测

为获得一株高效表达猪表皮生长因子(p EGF)的重组植物乳杆菌,并检测其生物活性,从仔猪肠道内容物中分离植物乳杆菌,选择其中生物活性最强的一株(Lp-1)为宿主。以商品化乳杆菌表达载体p IAβ8为骨架,干酪乳杆菌超强组成型启动子SCP、M6前体蛋白信号肽SP、猪表皮生长因子p EGF等为元件,构建表达p EGF的植物乳杆菌重组表达载体p SCPSE。用电转化方法 (2.0 k V,2 000?,25μF,4.0 ms)将重组载体p SCPSE转化入宿主菌Lp-1中获得重组植物乳杆菌Lp-p SCPSE。以Tricine-SDS-PAGE法和p EGF ELISA特异性检测试剂盒检测目的蛋白的表达;用培养12 h的阳性转化子菌体给刚断奶的BALB/c小鼠灌胃,2次/d,连续10 d,以断奶小鼠的体重、肠绒毛长度和隐窝深度的变化为指标,检测目的蛋白的生物活性。Tricine-SDS-PAGE检测和小鼠实验结果显示,重组植物乳杆菌的培养上清中出现6 k Da左右p EGF的特异性条带,且表达p EGF的重组植物乳杆菌能显著增加(P0.05)断奶小鼠的体重、肠绒毛高度和肠隐窝深度。结果表明,p EGF在植物乳杆菌中成功表达,且具有良好的生物学活性。     

Survival of Lactobacillus plantarum 44a after spraying and drying in feed and during exposure to gastrointestinal tract fluids in vitro

A good probiotic strain should be able to survive the conditions of handling and storage to be delivered in high concentration to the host. That is especially important when stressful conditions are prevalent in the carrier, for instance in low water content foods like animal feed. The aim of this research was to study the survival of the probiotic candidate Lactobacillus plantarum 44a after spraying and drying in feed, and during storage and exposure to gastrointestinal tract fluids in vitro. In addition, the viability of the strain during exposure to distilled water and 2% NaCl was studied. Feed was sprayed with a suspension of asymptotically equal to 2 x 10(10) CFU of L. plantarum 44a in 10, 15, 20, 25 and 30% v/w of the feed and dried to constant weight (6% moisture) in a convective oven at 25 degrees C. L. plantarum 44a survived 14.67, 36, 51.86, 78.9 and 105.3% respectively in relation to the original % v/w of the feed. After 3 weeks of storage at 25 degrees C, survival was similarly low in all the treatments. L. plantarum 44a stored in feed containing 13% moisture, vacuum-packaged and stored in refrigeration, maintained high viability (approximately 100%) after 1 year of storage. Survival was not affected after feed-containing lactobacilli was exposed to gastrointestinal fluids in a simulation model. Viability of L. plantarum 44a as a cell suspension in PBS added directly to distilled water or distilled water with 2% NaCl was maintained up to 48 h; after 72 h, viability started to decline. It is concluded that L. plantarum 44a maintained high viability after being dried and stored in feed even after exposure to gastric and intestinal fluids in vitro.     

接种植物乳杆菌(Lactobacillus plantarum)对小规模饲料稻青贮品质的影响

【目的】研究接种植物乳杆菌对小规模饲料稻品质的影响。【方法】以自然发酵的样品为对照,接种不同来源植物乳酸菌发酵饲料稻,发酵30 d后对饲料稻的感官进行评价;通过选择性平板对饲料稻青贮中的不同微生物进行计数;并采用V-Score评价法对发酵品质进行评定。【结果】相对自然发酵的样品而言,接种植物乳杆菌的青贮样品感官评分等级达到优良;乳酸菌为优势菌株,引起腐败变质的好氧菌、霉菌、大肠杆菌等受到抑制;接种发酵的样品中乳酸含量明显增加,氨态氮的产生量为对照的1/2左右,V-Score评分为满分。【结论】供试的植物乳杆菌,尤其是从青饲料和青贮材料中分离的菌株能有效改善饲料稻青贮的品质,可考虑用作青贮饲料稻发酵剂。