Study of the L-transforming action on Brucella cells of tetracycline, streptomycin, rifampicin and their combinations with penicillin in in vitro experiments]

The in vitro study of the possible formation of L-forms of Brucella under the effect of tetracycline, streptomycin, rifampicin or their combinations with penicillin showed that passages of various Brucella species on media containing increasing concentrations of the antibiotics resulted in insignificant morphological changes in the cells. Passages of the same cultures on media containing combinations of the above antibiotics with penicillin resulted in more significant changes in the cell morphology, up to formation of spheroplasts. No L-transformation was observed under the experimental conditions.     

Effect of penicillin and the habitat medium in the body of bacterial carriers on the intercellular bonds in populations of the meningococcus and pertussis microbe

The relationship of the bacterial cells in populations and their adhesion activity is at present one of the research priorities in microbiological studies. The stimulating effect of penicillin on the development of morphologically different intercellular bonds (IB) in populations of the pertussis causative agent and first of all derivatives or evaginates of the cell wall membranes was observed. Morphologically similar systems and polytubular IB were detected in populations of meningococcal strains isolated from carriers having no signs of the disease. Correlation between the after-effect of penicillin and the presence of the causative agent in bacterial carriers was shown. Unknown systems of interlacing tubular structures not directly bound with the cells, the walls of which were single contour membranes were determined in the meningococcal populations treated with penicillin. IB were observed in the population in the form of transpopulation cords. Morphologically different IB playing the role of specialized organelles might be considered as factors of the functional unity of the bacterial population as a multicellular system.     

Influence of oxygen concentration on the metabolism of Penicillium chrysogenum

In large-scale bioreactors, there is often insufficient mixing and as a consequence, cells experience uneven substrate and oxygen levels that influence product formation. In this study, the influence of dissolved oxygen (DO) gradients on the primary and secondary metabolism of a high producing industrial strain of Penicillium chrysogenum was investigated. Within a wide range of DO concentrations, obtained under chemostat conditions, we observed different responses from P. chrysogenum: (i) no influence on growth or penicillin production (>0.025 mmol L⁻¹); (ii) reduced penicillin production, but no growth limitation (0.013–0.025 mmol L⁻¹); and (iii) growth and penicillin production limitations (<0.013 mmol L⁻¹). In addition, scale down experiments were performed by oscillating the DO concentration in the bioreactor. We found that during DO oscillation, the penicillin production rate decreased below the value observed when a constant DO equal to the average oscillating DO value was used. To understand and predict the influence of oxygen levels on primary metabolism and penicillin production, we developed a black box model that was linked to a detailed kinetic model of the penicillin pathway. The model simulations represented the experimental data during the step experiments; however, during the oscillation experiments the predictions deviated, indicating the involvement of the central metabolism in penicillin production.     

Preferential Inhibition of Penicillinase Induction by Oxytetracycline and Its Effect on the Penicillin Susceptibility of Staphylococci

Exposure of penicillinase-producing staphylococci to a combination of penicillin and oxytetracycline resulted in a synergistic inhibitory activity of the antibiotics on the bacteria. Oxytetracycline was employed in concentrations having little or no effect on bacterial growth. It was found that the synergistic antibacterial effect was caused by the preferential inhibition of penicillinase induction by oxytetracycline, rendering the staphylococci more susceptible to penicillin.     

A rapid method for determination of in vitro susceptibility to antibiotics with a bulk acoustic wave bacterial growth biosensor

A novel bulk acoustic wave (BAW) bacterial growth biosensor was developed to study in vitro susceptibility by continuous monitoring of disturbances of bacterial growth at low antibiotic concentrations, followed by the accurate and rapid estimation of growth kinetic parameters and minimum inhibitory concentrations (MICs). The susceptibilities of bacteria, e.g. Escherichia coli, Staphylococcus aureus, Proteus vulgaris, Pr. morganii and Pr. mirabilis , to various antibiotics, e.g. penicillin, streptomycin, gentamicin and cefotaxime, were investigated, respectively, and the MICs were rapidly determined with a higher reproducibility than the conventional broth micro-dilution technique (BMDT). The effects of cell constant of conductivity electrode, pH and temperature on bacterial growth and biosensor signals were discussed in detail. The proposed method offers an effective alternative to the conventional methods.     

Comparative study of 6-APA production by free and agar immobilized bacteria in nutrient broth culture

In the present study different bacterial samples were isolated from soil of different places of Dibrugarh and screened for biotransformation ability to produce 6-Aminopenicillanic acid. Among ten isolated bacterial samples, three gram positive bacterial samples designated as AKDD-2, AKDD-4 and AKDD-6 showed the production of 6-APA from penicillin G. Assessment of production of 6-APA after incubation in penicillin G (2 mg/ml) by three different samples separately in free and agar immobilization state was done by HPLC analysis. Reusability of immobilized cells was found successful up to 14 days.     

Identification of genes and proteins involved in the pleiotropic response to arsenic stress in Caenibacter arsenoxydans, a metalloresistant beta-proteobacterium with an unsequenced genome

The effect of high concentrations of arsenic has been investigated in Caenibacter arsenoxydans, a beta-proteobacterium isolated from an arsenic contaminated environment and able to oxidize arsenite to arsenate. As the genome of this bacterium has not yet been sequenced, the use of a specific proteomic approach based on nano-high performance liquid chromatography tandem mass spectrometry (nanoLC-MS/MS) studies and de novo sequencing to perform cross-species protein identifications was necessary. In addition, a random mutational analysis was performed. Twenty-two proteins and 16 genes were shown to be differentially accumulated and expressed, respectively, in cells grown in the presence of arsenite. Two genes involved in arsenite oxidation and one in arsenite efflux as well as two proteins responsible for arsenate reduction were identified. Moreover, numerous genes and proteins belonging to various functional classes including information and regulation pathways, intermediary metabolism, cell envelope and cellular processes were also up- or down-regulated, which demonstrates that bacterial response to arsenic is pleiotropic.     

Apelin and stem cells: the role played in the cardiovascular system and energy metabolism

Apelin, a member of the adipokine family, is widely distributed in the body and exerts cytoprotective effects on many organs. Apelin isoforms are involved in different physiological processes, including regulation of the cardiovascular system, cardiac contractility, angiogenesis, and energy metabolism. Several investigations have been performed to study the effect of apelin on stem cell therapy. This review aims to summarize the literature representing the effects of apelin on stem cell properties. Furthermore, this review discusses the therapeutic potential of apelin‐treated stem cells for cardiovascular diseases and demonstrates the effect of stem cells overexpressing apelin on energy metabolism. Stem cells with their unique characteristics play a crucial role in the maintenance of tissue integrity. These cells participate in tissue regeneration via multiple mechanisms. Although preclinical and clinical studies have demonstrated the therapeutic potential of stem cells in various diseases, their application in regenerative medicine has not been efficient. A number of strategies such as genetic modification or treatment of stem cells with different factors have been used to improve the efficacy of cell therapy and to increase their survival after transplantation. This article reviews the effect of apelin treatment on the efficacy of cell therapy.     

Expression and Purification of the Main Component Contained in Camel Milk and Its Antimicrobial Activities Against Bacterial Plant Pathogens

Lactoferrin is the most dominant protein in milk after casein. This protein plays a crucial role in many biological processes including the regulation of iron metabolism, induction and modulation of the immune system, the primary defense against microorganisms, inhibiting lipid peroxidation and presenting antimicrobial activity against various pathogens such as parasites, fungi, bacteria, and viruses. The major antimicrobial effect of lactoferrin is related to its N-terminal tail where different peptides for instance lactoferricin and lactoferrampin which are important for their antimicrobial abilities are present. The growth rate of bacterial cells in camel milk is lower than that of the cow milk due to having more antimicrobial compounds. In this study, we have fused a codon-optimized partial camel lactoferrcin and lactoferrampin DNA sequences in order to construct a fused peptide via a lysine. This chimeric 42-mer peptide consists of complete and partial amino acid sequence of camel lactoferrampin and lactoferricin, respectively. Human embryonic kidney 293 (HEK-293) cells were used for synthesizing this recombinant peptide. Finally, the antibacterial activities of this constructed peptide were investigated under in vitro condition. The result showed that, all construction, cloning and expression processes were successfully performed in HEK-293. One His-tag tail was added to the chimera in order to optimize the isolation and purification processes and also reduce the cost of production. Additionally, His-tag retained the antimicrobial activity of the chimera. The antimicrobial tests showed that the growth rate in the majority of bacterial plant pathogens, including gram negative and positive bacteria, was inhibited by recombinant chimera as the level of MIC values were evaluated between 0.39 and 25.07 μg/ml for different bacterial isolates.     

Effect of phenylacetic acid feeding on the process of cellular autolysis in submerged batch cultures of Penicillium chrysogenum.

The effects of feeding the 'toxic' penicillin precursor, phenylacetic acid (PAA) at varying rates, upon the process of cellular autolysis, was assessed in batch bioreactor cultures of an industrial strain of Penicillium chrysogenum. Five processes were fed at rates which resulted in extracellular concentrations of PAA ranging from zero (the control) to approximately ten times levels said to be optimal for penicillin biosynthesis. The culture response was assessed chemically and morphologically, using computerised image analysis. High concentrations of PAA reduced biomass and penicillin production, and were associated with increased cellular autolysis. However, the values of classical morphological indices (branch length, main hyphal length and hyphal growth unit) varied little in cultures which showed extensive autolysis and biomass loss. Lower precursor concentrations (0.01 to 1.0 g l-1) had little effect on biomass, penicillin, or upon the levels of autolysis compared with the control process. Therefore, precursor concentration controlled within the optimal range for penicillin production, has little impact upon differentiation or degradation within an industrial culture of P. chrysogenum. By contrast, exploitation of the toxicity of PAA is proposed as a means to bring forward or enhance autolysis, providing a reliable method of 'induction' with which to study the phenomenon in P. chrysogenum.     

Quantitative analysis of the intramacrophagic Brucella suis proteome reveals metabolic adaptation to late stage of cellular infection

A 2-D DIGE approach allowed the characterization of the intramacrophagic proteome of the intracellular pathogen Brucella suis at the late stage of in vitro infection by efficient discrimination between bacterial and host cell proteins. Using a subtraction model, a total of 168 proteins showing altered concentrations in comparison with extracellularly grown, stationary-phase bacteria were identified. The majority of the 44 proteins significantly regulated at this stage of infection were involved in bacterial metabolism and 40% were present in lowered concentrations, supporting the hypothesis of an adaptive response by quantitative reduction of processes participating in energy, protein, and nucleic acid metabolism. In the future, the 2-D DIGE-based approach will permit to decipher specifically and quantitatively the intracellular proteomes of various pathogens during adaptation to their specific host cell environments.     

Application of metabolic flux analysis for the identification of metabolic bottlenecks in the biosynthesis of penicillin-G

A detailed stoichiometric model was developed for growth and penicillin-G production in Penicillium chrysogenum. From an a priori metabolic flux analysis using this model it appeared that penicillin production requires significant changes in fluxes through the primary metabolic pathways. This is brought about by the biosynthesis of carbon precursors for the beta-lactan nucleus and an increased demand for NADPH, mainly for sulfate reduction. As a result, significant changes in flux partitioning occur around four principal nodes in primary metabolism. These are located at: (1) glucose-6-phosphate; (2) 3-phosphoglycerate; (3) mitochondrial pyruvate; and (4) mitochondrial isocitrate. These nodes should be regarded as potential bottlenecks for increased productivity. The flexibility of these principal nodes was investigated by experimental manipulation of the fluxes through the central metabolic pathways using a high-producing strain of P. chrysogenum. Metabolic fluxes were manipulated through growth of the cells on different substrates in carbon-limited chemostat culture. Metabolic flux analysis, based on measured input and output fluxes, was used to calculate the fluxes around the principal nodes. It was found that, for growth on glucose, ethanol, and acetate, the flux partitioning around these nodes differed significantly. However, this had hardly any effect on penicillin productivity, showing that primary carbon metabolism is not likely to contain potential bottlenecks. Further experiments were performed to manipulate the total metabolic demand for the cofactor nicotinamide adenine dinucleotide phosphate (NADPH). NADPH demand was increased stepwise by cultivating the cells on glucose or xylose as the carbon source combined with either ammonia or nitrate as the nitrogen source, which resulted in a stepwise decrease of penicillin production. This clearly shows that, in penicillin fermentation, possible limitations in primary metabolism reside in the supply/regeneration of cofactors (NADPH) rather than in the supply of carbon precursors.     

Effect of colloid gold on physiologic-biochemical processes in Escherichia coli 1257

The influence of colloid gold on the growth processes, ATP-ase activity and extrusion of protons in Escherichia coli 1257 was studied. The particles of colloid gold exert nonmonotonous influence on these processes with different direction is such a way that small concentration of this metal (5 x 10(-7)-5 x 10(-6) mg/ml) exert stimulative effect, while higher concentrations of colloid gold result in the suppression of biological activity of the bacterial cells. The discovered peculiarities of colloid gold influence of E. coli strain may be determined by specificity of contact interaction of metal particles with the surface of bacterial cells.     

Synergistic action of combinations of penicillin and perhydroacridine derivatives

The effect of combinations of perhydroacridine derivatives such as 10-nitroso-trans-anti-cys-perhydroacridine (MT-2) and 10-isopropylamino-trans-anti-cys-perhydroacridine (MT-6) with benzylpenicillin on growth of two penicillinase-producing strains of Staphylococcus aureus was studied. The combination components were added to the culture simultaneously or at different periods i.e. the second component was added after preliminary exposure of the bacterial cells to the first component for 1-6 hours at 37 degrees C. It was shown that duration and efficacy of the combination synergistic action were directly proportional to the time of the component addition. The highest synergistic action of the combinations was observed when both the components were simultaneously added to the staphylococcal culture. The combinations were less efficient when the bacterial cells were preliminarily incubated with the perhydroacridines. Addition of the perhydroacridine derivatives after the strain contact with the penicillin resulted in elimination of the combination synergistic action. Thin-layer chromatography did not reveal complexing between the penicillin and perhydroacridines.     

The effect of alpha-lactalbumin and beta-lactoglobulin hydrolysates on the metabolic activity of Escherichia coli JM103

Bovine milk proteins alpha-lactalbumin (alpha-la) and beta-lactoglobulin (beta-lg) were hydrolysed with seven different proteolytic enzymes, and the effect of various hydrolysates on a genetically modified luminous Escherichia coli JM103 was tested in vitro with a bioluminescence assay for bacterial growth and metabolism. Undigested proteins did not inhibit the activity of tested E. coli JM103 at a concentration as high as 0.1 g ml-1. At the same concentrations, alpha-la hydrolysed with pepsin or trypsin and beta-lg hydrolysed with alcalase, pepsin or trypsin, showed a lower metabolic activity during the first 8 h of growth. The activity of E. coli JM103 in the presence of 25 mg ml-1 alpha-la or beta-lg hydrolysed with pepsin and trypsin was only 21% of the control after incubation for 6 h. The preliminary results indicated that ultrafiltration through 10 kDa and 1 kDa molecular mass cut-off membranes may be used to enrich bacteriostatic properties.     

Bacterial monocultures, propionate, butyrate and H2O2 modulate the expression, secretion and structure of the fasting-induced adipose factor in gut epithelial cell lines

Previous research showed that an intestinal microbial community represses the fasting-induced adipose factor (FIAF) in the gut epithelium, thereby increasing fat storage in the host. This study was designed to investigate the overall effect of different bacterial species and metabolites on FIAF in intestinal (Caco-2, HT-29 and HCT-116) and hepatic (HepG2) cancer cell lines. First, we showed that FIAF was present in different isoforms, and secreted as N-glycosylated proteins, exclusively at the basal side of the cell monolayer. Second, co-incubation of cell lines with bacterial monocultures and metabolites altered both FIAF production and isoform appearance. Propionate and/or butyrate treatment increased FIAF expression and cleavage in all tested cell lines. In contrast, different bacteria induced cell line-specific FIAF modulation. Clostridium perfringens induced FIAF isoform changes in Caco-2 cells. Enterococcus faecalis and Bacteroides thetaiotaomicron treatment resulted in cell line-specific FIAF increases, whereas Escherichia coli significantly decreased FIAF expression in HCT-116 cells. Treatment with H(2) O(2) and peroxide-producing E. faecalis strains induced FIAF isoform changes in Caco-2 cells. Since bacteria and bacterial metabolites alter both FIAF production and isoform appearance, further investigation may reveal an important role for bacteria in FIAF-regulated physiological processes, such as cell differentiation and fat metabolism.     

Radioprotective effect of a herbal product soma

A study was undertaken to examine the functional activity of the synthetic apparatus of rat blood lymphocytes by fluorescence microspectroscopy and the metabolic indices of the animals during the use of the herbal product Soma in normalcy and in acute x-irradiation. It was shown that Soma in normalcy caused a reliable increase in the synthetic activity of the cells with respect to the reference value on the 13th and 20th days of administration. Prior use of Soma for a month with subsequent pause increased the radioresistance of the animal organism (scheme 1), whereas the use of Soma immediately after irradiation (scheme 2) had no appreciable radioprotective effect. The study showed the effect of Soma on enhancement of metabolism, which may play an important role in restoration of the homeostasis of the organism. The results obtained suggest the expediency of further investigation of the radioprotective properties of Soma using various concentrations and administration schemes.     

Influence of antimicrobial subinhibitory concentrations on hemolytic activity and bacteriocin-like substances in oral Fusobacterium nucleatum

Fusobacterium nucleatum is considered for its role in colonization of initial and late microorganisms in dental plaque and for its coaggregation with other bacterial species. It is known that action of different antimicrobial substances may interfere with either virulence factors or with host-bacteria interaction. The goal of this study was to examine the influence of subinhibitory concentrations of chlorhexidine, triclosan, penicillin G and metronidazole on hemolytic activity and bacteriocin-like substance production of oral F. nucleatum. A high resistance to penicillin G was observed and 63% of the isolates were beta-lactamase positive. All the tested isolates were susceptible to metronidazole. F. nucleatum isolates grown with or without antimicrobials were alpha-hemolytics. Bacteriocin-like substance production was increased in isolates grown with penicillin G. Impaired production of hemolytic or antagonic substances can suggest a role in the regulation of oral microbiota.     

4种抗生素对蚯蚓-污泥系统细菌群落结构的影响

蚯蚓可摄食污泥中的有机物,其肠道微生物群落在其分解过程中起着主要的作用。利用赤子爱胜蚓(Eisenia foetida)和人工湿地基质构建蚯蚓-污泥系统,添加氯霉素、四环素、链霉素和青霉素4种抗生素,研究不同抗生素对污泥和蚓粪的细菌群落结构的影响。采用高通量测序技术比较分析污泥和蚓粪的细菌多样性及群落结构变化。结果表明,外加抗生素能够导致污泥的Chao1和ACE指数降低,同时降低拟杆菌门和变形菌门的相对丰度,加入氯霉素和青霉素会增加厚壁菌门的相对丰度,降低酸杆菌门、放线菌门和绿弯菌门的相对丰度,加入四环素和链霉素则与之相反。蚓粪样品中,添加氯霉素和链霉素导致Chao1和ACE指数降低,而添加四环素和青霉素则导致Chao1和ACE指数升高,外加抗生素可降低拟杆菌门的相对丰度,增加放线菌门、变形菌门和疣微菌门的相对丰度。主成分分析(PCA)和聚类分析表明,氯霉素和青霉素对污泥细菌群落影响作用相似,四环素与链霉素效果类似;氯霉素对蚓粪群落结构的影响小于其他抗生素。研究结果显示,抗生素可影响污泥和蚓粪的细菌多样性及群落结构,不同抗生素对污泥和蚓粪的影响程度存在差异。