Starch nanoparticles as a new ice crystal nucleator in Lactobacillus bulgaricus CICC 6097 cryoprotection.

This work aimed at studying the cryoprotective effect of starch nanoparticles (SNPs) as ice nucleators on Lactobacillus bulgaricus CICC 6097 and exploring the protective mechanism. SNPs with a diameter of 363 nm were obtained, which possessed special properties to enhance ice nucleation and blunt ice crystals edges, and can be wrapped around the surface of bacteria form a protective barrier, thus maintaining the integrity of cell membranes and improving the survivability of L. bulgaricus CICC 6097 from 36.09% to 75.56%. However, SNCs solution formed ice crystals with obvious spikes during freezing, which was harmful to bacteria survival. Therefore, SNPs addition is a possible strategy for increasing viable cell counts during freezing. To the best of our knowledge, this report is the first to demonstrate the cryoprotective effect of ice nucleator on lactic acid bacteria.

Detoxification of cancerogenic compounds by lactic acid bacteria strains.

Carcinogens in food are an important issue that threat people's health right now. Lactic acid bacteria (LAB) strains as well-known probiotics have shown numerous perspectives in being used as a good food additive to confront cancerogenic compounds in recent years. Some LAB strains can remove cancerogenic compounds from medium environment via direct physical binding and avoid re-pollution of poisonous secondary metabolites which are generated from degradation of cancerogenic compounds. This article presents a whole overview of the physical-binding of LAB strains to such common cancerogenic compounds existed in food and feed environments as mycotoxins, polycyclic aromatic hydrocarbons (PAHs), heterocyclic amines (HAs) and pthalic acid esters (PAEs).In most cases, summaries of these published researches show that the binding of LAB strains to cancerogenic compounds is a physical process. Binding sites generally take place in cell wall, and peptidoglycan from LAB cells is the chief binding site. The adsorption of lactic acid bacteria to cancerogenic compounds is strain-specific. Specially, the strains from the two genera Lactobacillus and Bifidobacterium show a better potential in binding cancerogenic compounds. Moreover, we firstly used molecular dynamic computer model as a highly potential tool to simulate the binding behavior of peptidoglycan from Lactobacillus acidophilus to DBP, one of pthalic acid esters with genetic toxicity. It was seen that the theoretical data were quite consistent with the experimental results in terms of the ability of this bacterium to bind DBP. Also, the toxicity reduction of cancerogenic compounds by LAB strains could be achieved either in gastrointestinal model or animal tests and clinical researches as well. In conclusion, carefully selected LAB strains should be a good solution as one of safety strategies to reduce potential risk of cancerogenic compounds from food-based products.

Screening lactic acid bacteria strains with ability to bind di-n-butyl phthalate via Turbiscan technique.

Di-n-butyl phthalate (DBP) is a ubiquitous environmental contaminant that poses a risk to humans. Previous work indicates that the ability of lactic acid bacteria (LAB) to bind phthalic acid esters is strain-specific. As cell suspensions of LAB strains in aqueous solution are likely to be colloidal dispersions, this study provided a technique to efficiently screen LAB strains that bind DBP via Turbiscan, which has been widely used to measure the stability of emulsions or colloidal dispersions. Eleven LAB strains belonging to Lactobacillus plantarum, Lb. pentosus, Lb. paralimentarius, Lb. helveticus, Leuconostoc mesenteroides, Lb. acidophilus, Bifidobacterium lactis, and Bifidobacterium bifidum species were used in this study, and seven of them were selected to test in an earlier stage of exploring the process for finding a screening method; others were used for a validation test. It was observed that the various values of the 10 h Turbiscan Stability Index (TSI) of the cell suspension from each strain, at the equilibrium time of dispersed particles according to the peak thickness of cell-suspensions as measured by Turbiscan, had significant negative correlations with the DBP-binding percentage of LAB strains. Higher TSI values are correlated with lower binding of bacteria strains to DBP with a correlation coefficient of 0.8292. Cell surface hydrocarbons of LAB strains and their adherence were observed to correlate with DBP-binding percentages and may lead to the different states of aggregation or equilibrium of bacterial cell-suspensions, and the aggregation of bacterial cells resulted in fewer binding sites in the cell wall for DBP. Finally, four LAB strains were randomly selected to verify the feasibility of the method. In all, the findings demonstrate that TSI might be used as a tool to quickly screen strains that bind DBP. The present work could be extended to the removal of other toxic compounds, when screening of high-efficiency strains is required.

CT differentiation between tuberculous spondylitis and pyogenic spondylitis / 实用放射学杂志

Objective This study was to investigate the computed tomography(CT)features differentiating tuberculous spondyli-tis from pyogenic spondylitis.Methods The CT features in 32 patients with tuberculous spondylitis and 30 patients with pyogenic spondylitis were retrospectively reviewed,and statistically analyzed.Results In 32 cases of tuberculous spondylitis,71 vertebra were involved.In 30 cases of pyogenic spondylitis,59 vertebra were involved.The incidence of thoracic vertebra involvement in tuberculous spondylitis was 60.56% (43/71),which was higher than that in pyogenic spondylitis (25.42%,1 5/59)(P <0.05).The incidence of lumbar vertebra involvement in tuberculous spondylitis was 33.80% (24/71 ),which was lower than that in pyogenic spondylitis (61.02%,36/59)(P <0.05).The incidence of the worm-eaten type of bone destruction in tuberculous spondylitis was 9.90% (7/71),which was lower than that in pyogenic spondylitis (44.07%,26/59)(P <0.05).The incidence of the fragmentary type of bone destruction in tuberculous spondylitis was 1 9.72%(14/71 ),which was higher than that of in pyogenic spondylitis (3.39%,2/59) (P <0.05).The incidence of large osteosclerosis in tuberculous spondylitis was 52.1 1%(37/71),which was higher than that in pyo-genic sp-ondylitis (22.03%,13/59),(P <0.05).The incidence of the involved vertebral height on sagital CT scan (less than the 1/2 of the normal vertebral height)in tuberculous spondylitis was 1 6.9% (12/71),which was lower than that in pyogenic spondylits (62.71%,37/59)(P <0.05).The incidence of patchy high density shadow in tuberculous spondylitis was 50.7% (36/71 ),which was higher than that in pyoge-nic spondylitis (20.34%,12/59)(P <0.05.)The incidence of the involvement of the appendages in tu-berculous spondylitis was 25.35% (18/71),which was higher than that in pyogenic spondylitis (8.47%,5/59)(P <0.05).The inci-dence of paravertebral abnormal soft tissue with calcification in tuberculous spondylitis was 60.00%(18/30),which was higher than that in pyogenic spondylitis(20.00%,5/25 )(P < 0.05 ).Conclusion Tuberculous spondylitis and pyogenic spondylitis have some characteristic imaging features,combined with the clinical signs differentiation diagnosis can be made each other.

Characterization of soybean protein hydrolysates able to promote the proliferation of Streptococcus thermophilus ST.

How soybean protein hydrolysates (SPHs) to favor the growth of S. thermophilus ST were investigated. Hydrolyzed soybean protein was fractionated to 4 fragments, that is, SPH-I, SPH-II, SPH-III, and SPH-IV according to their molecular weight sizes. SPHs can improve the growth of strain ST, in which SPH-IV, with the molecular weight of less than 5 kD, significantly promoted the growth of strain ST. The cell counts of strain ST grew quickly from 7.71 to 9.78 (log CFU/mL) when the concentrations of SPH-IV ranging from 0% to 1%. Moreover, 2 chemically defined media (CDMs) were used to test their roles in maintaining the viability of strain ST. CDMs only maintained the survival of strain ST, but SPH-IV had the promotional effects on proliferation of the bacteria. SPH-IV was further characterized to be oligopeptides that contain 2 to 8 amino acids and free amino acids by high-performance liquid chromatography-mass spectrometry (HPLC-MS) analysis. The amino acid compositions showed that SPH-IV contained more essential amino acids, which were necessary for the growth of S. thermophilus ST. Clearly, SPH-IV could be used as an exogenous nitrogen supplement to enhance the proliferation of S. thermophilus ST and other lactic acid bacteria, and the data from small scale-up fermentation also supported this point.