Degradation of the Isoflavone Biochanin A and Its Glucoside Conjugates by Ascochyta rabiei

Strains of Ascochyta rabiei which are pathogenic to chickpea (Cicer arietinum L.) readily catabolized the main chickpea isoflavone biochanin A (5,7-dihydroxy-4′-methoxyisoflavone). 3′-Hydroxylation and O-demethylation reactions led to the isoflavones pratensein, genistein, and orobol, which were rapidly further degraded. Dihydrogenistein and p-hydroxyphenylacetic acid were also identified as catabolites. Biochanin A-7-O-glucoside was degraded, leading to aglycone and pratensein. Biochanin A-7-O-glucoside-6″-O-malonate, the main phenolic constituent of chickpea, was very slowly degraded without subsequent accumulation of catabolites.     

拮抗菌株抑菌活性的保藏试验研究

研究不同保藏介质、温度和时间的综合因素对B-298菌株活性的影响。为生产和研究提供能保持该菌株抑菌活性的适宜保藏方法。试验结果表明：介质、温度、时间的交互作用对菌株细胞存活率和代谢产物拮抗效应的影响都存在显著性差异;细胞存活率和拮抗效应与保藏时间呈反比;菌株保藏680 d,应用甘油超低温保藏法,菌株细胞存活率和抑菌活性最高,而采用斜面常温保藏,细胞存活率和抑菌活性最低。     

Formulation and Optimization of Doxorubicin and Biochanin A Combinational Liposomes for Reversal of Chemoresistance

Circumvention of drug resistance still remains a challenge in the development of anticancer therapeutics. Combinational nano-formulations provide many avenues for effective cancer therapy and reversal of drug resistance. In the current study, combination of biochanin A (BioA) and doxorubicin (DOX) in liposomes were prepared and studied for its potential to reverse DOX resistance in COLO205 cells. After development and validation of DOX resistant cells of COLO205 (ColoR), dosing ratio of DOX and BioA for reversal of DOX resistance was determined by co-treatment in ColoR cells. As limited solubility and analytical data available for BioA, therefore solubility was studied for BioA and analytical method was developed for the combination. Combinational liposomes were prepared and optimized for both lipid content and surface charge by evaluating size, polydispersity index, zeta potential, and encapsulation efficiency. The optimized formulation had a size about 125 nm; zeta potential of ?19.5 mV and 70% encapsulation efficiency (EE) for BioA. Thus, prepared combinational liposomes of DOX and BioA were evaluated for its cellular uptake and efficacy to reverse DOX resistance. From the study, increased DOX uptake and promising effect for reversal of DOX resistance was observed.     

Initial Phases of Starvation and Activity of Bacteria at Surfaces

The activity of the hydrophilic Vibrio sp. strain DW1 and the hydrophobic Pseudomonas sp. strain S9, which both undergo starvation-induced responses, was examined at nutrient-enriched and nutrient-deficient interfaces. The initial period of response to a starvation regime (“dwarfing” phase) is a sequence of two processes: fragmentation and continuous size reduction of the fragmented cells. This dwarfing phase is also one of intense metabolic activity as supported by O₂ uptake measurements of the endogenous metabolism and the use of inhibitors of the proton flow, the electron transport chain, and membrane-bound ATPase. Hydrophilic bacteria become even smaller at nutrient-deficient surfaces than in the liquid phase upon starvation, and this is reflected in a higher endogenous metabolism exhibited by surface-associated cells compared with those in the liquid phase. On the other hand, hydrophobic bacteria dwarfing at surfaces did not exhibit a greater size reduction and exhibited an endogenous metabolism that was only slightly higher than that of cells in the liquid phase. Bacterial scavenging of surface-localized nutrients is related to the degree of irreversible binding of dwarf and starved bacteria, which in turn may be related to the degree of cell surface hydrophobicity.     

The Intracellular Water Activity of Bacteria in Relation to the Water Activity of the Growth Medium

Intracellular water activities ( a _w) calculated from the solute composition of various bacterial cells, are in good agreement with values derived from intracellular freezing point data. Further, and confirming literature results based on freezing points, the intracellular a _w was found to be generally equal to or lower than that of the growth medium.     

Type III Secretion, Contact-dependent Model for the Intracellular Development of Chlamydia

The medically significant genus Chlamydia is a class of obligate intracellular bacterial pathogens that replicate within vacuoles in host eukaryotic cells termed inclusions. Chlamydia's developmental cycle involves two forms; an infectious extracellular form, known as an elementary body (EB), and a non-infectious form, known as the reticulate body (RB), that replicates inside the vacuoles of the host cells. The RB surface is covered in projections that are in intimate contact with the inclusion membrane. Late in the developmental cycle, these reticulate bodies differentiate into the elementary body form. In this paper, we present a hypothesis for the modulation of these developmental events involving the contact-dependent type III secretion (TTS) system. TTS surface projections mediate intimate contact between the RB and the inclusion membrane. Below a certain number of projections, detachment of the RB provides a signal for late differentiation of RB into EB. We use data and develop a mathematical model investigating this hypothesis. If the hypothesis proves to be accurate, then we have shown that increasing the number of inclusions per host cell will increase the number of infectious progeny EB until some optimal number of inclusions. For more inclusions than this optimum, the infectious yield is reduced because of spatial restrictions. We also predict that a reduction in the number of projections on the surface of the RB (and as early as possible during development) will significantly reduce the burst size of infectious EB particles. Many of the results predicted by the model can be tested experimentally and may lead to the identification of potential targets for drug design.     

Studies Concerning the Prediction of Intracellular Water Activity of Bacteria Grown at Reduced Water Activities

The water activity of various salts, macromolecules and mixed salt-macromolecule solutions has been determined. The results indicate that interactions between salts and macromolecules can be ignored for predicting the water activity of mixed aqueous solutions.     

Cyclic Lipopeptide Biosynthetic Genes and Products,and Inhibitory Activity of Plant-Associated Bacillus against Phytopathogenic Bacteria

The antibacterial activity against bacterial plant pathogens and its relationships with the presence of the cyclic lipopeptide (cLP) biosynthetic genes ituC (iturin), bmyB (bacillomycin), fenD (fengycin) and srfAA (surfactin), and their corresponding antimicrobial peptide products have been studied in a collection of 64 strains of Bacillus spp. isolated from plant environments. The most frequent antimicrobial peptide (AMP) genes were bmyB, srfAA and fenD (34-50% of isolates). Most isolates (98.4%) produced surfactin isoforms, 90.6% iturins and 79.7% fengycins. The antibacterial activity was very frequent and generally intense among the collection of strains because 75% of the isolates were active against at least 6 of the 8 bacterial plant pathogens tested. Hierarchical and correspondence analysis confirmed the presence of two clearly differentiated groups. One group consisted of Bacillus strains that showed a strong antibacterial activity, presented several cLPs genes and produced several isoforms of cLPs simultaneously, mainly composed of B. subtilis and B. amyloliquefaciens, although the last one was exclusive to this group. Another group was characterized by strains with very low or none antibacterial activity, that showed one or none of the cLP genes and produced a few or none of the corresponding cLPs, and was the most heterogenous group including B. subtilis, B. licheniformis, B. megaterium, B. pumilus, B. cereus and B. thuringiensis, although the last two were exclusive to this group. This work demonstrated that the antagonistic capacity of plant-associated Bacillus against plant pathogenic bacteria is related to the presence of cLP genes and to the production of the corresponding cLPs, and it is mainly associated to the species B. subtilis and B. amyloliquefaciens. Our findings would help to increase the yield and efficiency of screening methods to obtain candidate strains to biocontrol agents with a mechanism of action relaying on the production of antimicrobial cLPs.     

Effect of Selected Types of Beer on Bacteria of the Genus Arcobacter

The genus Arcobacter is related to the well-known human pathogen, Campylobacter jejuni, and has been linked to human diseases. In this study, the survival of Arcobacter spp. in various concentrations of ethanol, in various samples of beers, and in a model stomach has been investigated. For most of these bacteria, a concentration of 10 % ethanol was determined to be the minimum inhibitory concentration. The fact that these organisms are able to survive under these conditions may have an impact in the food processing industry. We studied the activity of beer against arcobacters. These bacteria were killed in all samples of beer within 30 min. A model stomach, containing a food matrix and a synthetic gastric fluid, was used to deduce the effect of beer against Arcobacter spp. during food consumption. Complete inactivation of all monitored arcobacters was detected usually within 15 min. However, the presence of beer does not potentiate the effect of gastric fluid against these bacteria. This is apparently the first study focusing upon the effect of beer on Arcobacter spp.     

Ail and PagC-Related Proteins in the Entomopathogenic Bacteria of Photorhabdus Genus

Among pathogenic Enterobacteriaceae, the proteins of the Ail/OmpX/PagC family form a steadily growing family of outer membrane proteins with diverse biological properties, potentially involved in virulence such as human serum resistance, adhesion and entry into eukaryotic culture cells. We studied the proteins Ail/OmpX/PagC in the bacterial Photorhabdus genus. The Photorhabdus bacteria form symbiotic complexes with nematodes of Heterorhabditis species, associations which are pathogenic to insect larvae. Our phylogenetic analysis indicated that in Photorhabdus asymbiotica and Photorhabdus luminescens only Ail and PagC proteins are encoded. The genomic analysis revealed that the Photorhabdus ail and pagC genes were present in a unique copy, except two ail paralogs from P. luminescens. These genes, referred to as ail1 _Pl and ail2 _Pl, probably resulted from a recent tandem duplication. Surprisingly, only ail1 _Pl expression was directly controlled by PhoPQ and low external Mg²⁺ conditions. In P. luminescens, the magnesium-sensing two-component regulatory system PhoPQ regulates the outer membrane barrier and is required for pathogenicity against insects. In order to characterize Ail functions in Photorhabdus, we showed that only ail2 _Pl and pagC _Pl had the ability, when expressed into Escherichia coli, to confer resistance to complement in human serum. However no effect in resistance to antimicrobial peptides was found. Thus, the role of Ail and PagC proteins in Photorhabdus life cycle is discussed.     

A New Class of Tungsten-Containing Oxidoreductase in Caldicellulosiruptor,a Genus of Plant Biomass-Degrading Thermophilic Bacteria

Caldicellulosiruptor bescii grows optimally at 78°C and is able to decompose high concentrations of lignocellulosic plant biomass without the need for thermochemical pretreatment. C. bescii ferments both C₅ and C₆ sugars primarily to hydrogen gas, lactate, acetate, and CO₂ and is of particular interest for metabolic engineering applications given the recent availability of a genetic system. Developing optimal strains for technological use requires a detailed understanding of primary metabolism, particularly when the goal is to divert all available reductant (electrons) toward highly reduced products such as biofuels. During an analysis of the C. bescii genome sequence for oxidoreductase-type enzymes, evidence was uncovered to suggest that the primary redox metabolism of C. bescii has a completely uncharacterized aspect involving tungsten, a rarely used element in biology. An active tungsten utilization pathway in C. bescii was demonstrated by the heterologous production of a tungsten-requiring, aldehyde-oxidizing enzyme (AOR) from the hyperthermophilic archaeon Pyrococcus furiosus. Furthermore, C. bescii also contains a tungsten-based AOR-type enzyme, here termed XOR, which is phylogenetically unique, representing a completely new member of the AOR tungstoenzyme family. Moreover, in C. bescii, XOR represents ca. 2% of the cytoplasmic protein. XOR is proposed to play a key, but as yet undetermined, role in the primary redox metabolism of this cellulolytic microorganism.     

Role of Bacteria of the Genus Pseudomonas in the Sustainable Development of Agricultural Systems and Environmental Protection (Review)

Applied Biochemistry and Microbiology - The use of specialized cultures of microorganisms and biological products based on them is the most acceptable way to solve such topical problems as an...     

Depolymerization of Chitosan with a Chitinolytic Complex from Bacteria of the Genus Bacillussp. 739

Low-molecular-weight (3–6 kDa) water-soluble chitosan was obtained by enzymatic depolymerization. Hydrolysis of crab chitosan was induced by O-glycoside hydrolase (EC 3.2.1), the extracellular chitinolytic complex from Bacillussp. 739. The optimum conditions for hydrolysis were found (sodium–acetate buffer, pH 5.2; 55°C; and an enzyme/substrate ratio of 4 U per g chitosan; 1 h).     

1株血红蛋白分解菌的分离鉴定及其蛋白酶活力测定

为了获得能够有效降解利用屠宰场废弃血液的功能菌株,以日喀则地区屠宰场废弃血液堆积土壤样品为材料,将样品稀释涂布接种在血平板上进行分离,挑取水解圈最大的菌落进行平板划线纯化。对分离菌株进行形态学、生化反应试验、16S rDNA序列鉴定并测定其蛋白酶活性。筛选出1株能够高效降解血红蛋白的菌株命名为NwMCC01910042,该分离菌株为革兰阳性杆菌,V-P(Voges-Proskauer)试验阳性,枸橼酸盐利用、淀粉水解、明胶液化、16S rDNA序列系统进化分析显示NwMCC01910042菌株与Bacillus licheniformis ATCC 14580株的序列相似性为99.79%,与Bacillus licheniformis MSL3076株的序列相似性为99.30%,为地衣芽胞杆菌(Bacillus licheniformis),该菌株的16S rDNA序列已提交至GenBank,准入编号为MN 176417,其蛋白酶活力为188.63 U/mL。利用微生物降解生产氨基酸有机肥的关键是筛选蛋白酶的高产菌株,NwMCC01910042株菌有望作为将废弃血污降解为氨基酸的候选功能菌株。     

新型大豆异黄酮磺酸酯抑制血管平滑肌细胞增殖活性研究

为了寻找对血管平滑肌细胞异常增殖有较强抑制作用的化合物,本文用MMT法考察新型大豆苷元磺酸酯体外抑制血管平滑肌细胞增殖活性.结果表明:该大豆苷元磺酸酯对血管平滑肌细胞增殖在10-7 mol/L时有抑制作用(P＜0.05),该浓度下的抑制率为56.06％,与先导化合物大豆苷元相比活性提高约1000倍.构效关系研究表明,大豆苷元经苯磺酸酯修饰,改变分子的空间结构、分子的可极化率从26.51增加到54.12,改变了药物的电荷分布,更有利于药物通过细胞膜到达靶标和与靶标更精确作用而导致药物药理作用大大增强.药理实验与构效关系研究初步表明,该大豆苷元磺酸酯有进一步研究价值.     

Effect of Bacteria and Amoebae on Rhizosphere Phosphatase Activity

The contributions of various components of soil microflora and microfauna to rhizosphere phosphatase activity were determined with hydroponic cultures. Three treatments were employed: (i) plants alone (Bouteloua gracilis (H.B.K.) Lag. ex Steud.) (ii) plants plus bacteria (Pseudomonas sp.), and (iii) plants plus bacteria plus amoebae (Acanthamoeba sp.). No alkaline phosphatase was detected, but an appreciable amount of acid phosphatase activity (120 to 500 nmol of p-nitrophenylphosphate hydrolyzed per h per plant) was found in the root culture solutions. The presence of bacteria or bacteria and amoebae increased the amount of acid phosphatase in solution, and properties of additional activity were identical to properties of plant acid phosphatase. The presence of bacteria or bacteria and amoebae increased both solution and root phosphatase activities at most initial phosphate concentrations.     

Studies on the Developmental Cycle of Chlamydia trachomatis: Isolation and Characterization of the Initial Bodies

The initial bodies which develop in the inclusion bodies of trachoma agent (Chlamydia trachomatis) were separated from the infected cells nuclei and cytoplasmic components by zone centrifugation in sucrose gradients. The initial bodies are the site of the agent's ribonucleic acid synthesis and serve as precursors to the elementary bodies. The conversion of the initial bodies to elementary bodies is through a process which resembles binary fission. The effects of antibiotics on the development of the trachoma agent initial bodies revealed that rifampin prevented and hydroxyurea affected the formation of the initial bodies. Penicillin led to the formation of structures larger than the initial bodies.