Taxonomic distribution of <Emphasis Type="Italic">Streptomyces</Emphasis> species capable of producing bioactive compounds among strains preserved at NITE/NBRC

The taxonomic distribution of Streptomyces species capable of producing bioactive compounds was investigated. Nine hundred and six strains were tested for the following four biological activities: antimicrobial, anti-tyrosinase, antioxidant, and hemolytic. Approximately 30% of strains tested showed antimicrobial activities, except for anti-Escherichia coli activity, which was present in only a few strains, while the rates of positivity for the anti-tyrosinase, antioxidant, and hemolytic activities were much lower. The distribution of Streptomyces strains capable of producing bioactive compounds was analyzed by the taxonomy based on 16S rRNA gene sequences. Moreover, the strains of Streptomyces hygroscopicus tested were divided into two clades in the phylogenetic tree, and all of the strains belonging to one clade showed antibacterial and antifungal activities. For detection of polyenes, the UV-visible spectra of metabolic extracts in the strains showing antifungal activities were measured. It was suggested that Streptomyces strains produce universal active compounds under different growth conditions. Further information on the relationship between the microbial taxonomy and the bioactive compounds produced would be useful for the utilization of industrial microorganisms.     

新疆乌恰县豆科植物根瘤菌数值分类研究

新疆乌恰县具有独特的地理环境与气候条件,蕴藏着丰富的结瘤豆科植物资源.本研究从乌恰县豆科植物根瘤中分离到40株根瘤菌,并进行唯一碳源利用、唯一氮源利用、对抗生素和染料的抗性、耐盐性、初始pH生长、生长温度范围及石蕊牛奶反应、氧化酶、过氧化氢酶、脲酶共118项生理生化性状测定.结果表明:乌恰县豆科植物根瘤菌在碳氮源利用、抗生素敏感性、对染料抗性程度等方面存在着差异.供试根瘤菌能耐受较低温度,并具有较强的耐盐、碱能力,均能在pH 6~12的YMA培养基上生长,有60%的菌株能耐受0.86mol/L的NaCl.数值分类结果表明,在84.2%的相似水平上40株供试菌株构成了4个新的表观群.第Ⅰ、Ⅱ、Ⅲ和Ⅳ类群分别有8、9、3和3株菌,中心菌株分别为NWWQ73-2、NWWQ13-1、NWWQ1-2、NWWQ6-2.此外,乌恰县豆科植物根瘤菌与模式菌株的相似性较低,它们所形成的4个独立群可能有新种存在.     

Isolation and characteristics of a skatole-producing Lactobacillus sp. from the bovine rumen.

A bacterium that is capable of decarboxylating indoleacetic acid to skatole (3-methylindole) has been isolated from an L-tryptophan enrichment of bovine rumen fluid. The bacterium is a gram-positive, nonmotile, nonsporeforming rod. It is an obligate anaerobe, and strains predominatly produce D-(-)-lactic acid, with smaller amounts of L-(+)-lactic acid and acetic acid, from sugar. All four strains isolated gave a negative reaction to the indole test because they cannot form skatole directly from tryptophan. This is the first report of indoleacetic acid decarboxylation to skatole in pure culture and the demonstration of skatole production by a Lactobacillus species.     

Characterization of Exopolysaccharides Produced by Plant-Associated Fluorescent Pseudomonads

A total of 214 strains of plant-associated fluorescent pseudomonads were screened for the ability to produce the acidic exopolysaccharide (EPS) alginate on various solid media. The fluorescent pseudomonads studied were saprophytic, saprophytic with known biocontrol potential, or plant pathogenic. Approximately 10% of these strains exhibited mucoid growth under the conditions used. The EPSs produced by 20 strains were isolated, purified, and characterized. Of the 20 strains examined, 6 produced acetylated alginate as an acidic EPS. These strains included a Pseudomonas aeruginosa strain reported to cause a dry rot of onion, a strain of P. viridiflava with soft-rotting ability, and four strains of P. fluorescens. However, 12 strains of P. fluorescens produced a novel acidic EPS (marginalan) composed of glucose and galactose (1:1 molar ratio) substituted with pyruvate and succinate. Three of these strains were soft-rotting agents. Two additional soft-rotting strains of P. fluorescens produced a third acidic novel EPS composed of rhamnose, mannose, and glucose (1:1:1 molar ratio) substituted with pyruvate and acetate. When sucrose was present as the primary carbon source, certain strains produced the neutral polymer levan (a fructan) rather than an acidic EPS. Levan was produced by most strains capable of synthesizing alginate or the novel acidic EPS containing rhamnose, mannose, and glucose but not by strains capable of marginalan production. It is now evident that the group of bacteria belonging to the fluorescent pseudomonads is capable of elaborating a diverse array of acidic EPSs rather than solely alginate.     

Screening of bacterial strains capable of converting biodiesel‐derived raw glycerol into 1,3‐propanediol, 2,3‐butanediol and ethanol

The ability of bacterial strains to assimilate glycerol derived from biodiesel facilities to produce metabolic compounds of importance for the food, textile and chemical industry, such as 1,3‐propanediol (PD), 2,3‐butanediol (BD) and ethanol (EtOH), was assessed. The screening of 84 bacterial strains was performed using glycerol as carbon source. After initial trials, 12 strains were identified capable of consuming raw glycerol under anaerobic conditions, whereas 5 strains consumed glycerol under aerobiosis. A plethora of metabolic compounds was synthesized; in anaerobic batch‐bioreactor cultures PD in quantities up to 11.3 g/L was produced by Clostridium butyricum NRRL B‐23495, while the respective value was 10.1 g/L for a newly isolated Citrobacter freundii. Adaptation of Cl. butyricum at higher initial glycerol concentration resulted in a PD_max concentration of ～32 g/L. BD was produced by a new Enterobacter aerogenes isolate in shake‐flask experiments, under fully aerobic conditions, with a maximum concentration of ～22 g/L which was achieved at an initial glycerol quantity of 55 g/L. A new Klebsiella oxytoca isolate converted waste glycerol into mixtures of PD, BD and EtOH at various ratios. Finally, another new C. freundii isolate converted waste glycerol into EtOH in anaerobic batch‐bioreactor cultures with constant pH, achieving a final EtOH concentration of 14.5 g/L, a conversion yield of 0.45 g/g and a volumetric productivity of ～0.7 g/L/h. As a conclusion, the current study confirmed the utilization of biodiesel‐derived raw glycerol as an appropriate substrate for the production of PD, BD and EtOH by several newly isolated bacterial strains under different experimental conditions.     

海水中DHA产生菌的筛选及一株高产菌的鉴定

从海水中筛选产DHA的微生物,共采集海水样品280余份,用苏丹黑染色法得到160株产油脂菌株,在对60株脂肪粒较大的微生物用索氏抽提法提取油脂后,初筛得到油脂含量高于8%的菌株7株。对10株油脂产量较高的菌株进行复筛,编号7-3的菌株油脂含量达到15.9%,DHA在油脂中的含量达到45.2%,选用7-3作为目的菌株。对7-3进行形态特征、培养特征及生理生化特征鉴定,初步判定菌株7-3为酒香酵母属(Brettanomyces sp.)。     

Haemolytic activity of Morganella morganii strains

Haemolytic activity on solid and liquid media of 103 Morganella morganii strains isolated from clinical sources was investigated. The ability to produce haemolysin was found in 42.7% of strains. All strains capable to produce haemolysin on blood agar media also revealed haemolytic activity in some liquid media. Haemolysins were found in the supernatants and filtrates of the cultures in peptone water but not in Brain Heart Infusion and Trypticase Soy Broth. The maximal titer of haemolysin was observed in the logarithmic phase of growth. Heating and incubation with trypsin led to complete loss of haemolytic activity.     

Production of L-phenylacetyl carbinol by biotransformation: product and by-product formation and activities of the key enzymes in wild-type and ADH isoenzyme mutants of Saccharomyces cerevisiae

The capacities of yeast wild-type and mutants strains known to lack specific ADH isoenzymes to produce L-phenylacetyl carbinol (PAC) and benzyl alcohol in biotransformation trials were also investigated. Pyruvate decarboxylase activity, responsible for PAC formation and ADH activity, which can participate in reduction of benzaldehyde to benzyl alcohol, was also determined in each strain. In addition, the capacity of each strain to produce ethanol was investigated. Mutant strains lacking all of the isoenzymes, ADH-I, ADH-II, and ADH-III, still exhibited some ADH activity and were capable of production of benzyl alcohol and ethanol.     

Putrescine Accumulation in Wine: Role of Oenococcus oeni

Putrescine, the most abundant biogenic amine in wine, was proved to be produced by Oenococcus oeni strains in wine not only from ornithine but also from arginine. In this case, putrescine may originate from strains possessing the complete enzyme system to convert arginine to putrescine or by a metabiotic association, with an exchange of ornithine, between strains capable of metabolizing arginine to ornithine but unable to produce putrescine and strains capable of producing putrescine from ornithine but unable to degrade arginine. Putrescine production by this metabiotic association occurred once the malolactic fermentation was completed, whereas conversion of ornithine to putrescine by a single culture of the ornithine decarboxylating strain concurred with the degradation of malic acid. Moreover, in the former case, putrescine formation proceeded more slowly than in the latter. Metabiosis may play an important role in the accumulation of putrescine in wine, arginine being one of the major amino acids found in wine.     

Production of exotoxins by Aeromonas spp. at 5 degrees C

The ability of 60 strains of Aeromonas to produce enterotoxin and haemolysin after cultivation at 5 degrees C for 7-10 d was investigated. The strains were isolated from lamb meat, offal, carcasses and faeces, and had previously been tested for their ability to produce these exotoxins at 37 degrees C. The results showed that some strains of Aeromonas hydrophila and A. sobria were capable of producing enterotoxin and haemolysin at 5 degrees C, but none of the A. caviae strains tested produced these two factors. Of the 30 A. hydrophila strains investigated 25 and 27 were enterotoxigenic and haemolytic respectively. Likewise, of the 24 A. sobria strains investigated 16 and 18 were enterotoxigenic and haemolytic respectively. The results indicate that certain strains of Aeromonas species, in particular A. hydrophila and A. sobria, are of potential public health significance in meats stored at refrigeration temperature.     

Effect of itraconazole on the process of mycelial transformation of Candida albicans cells in human serum

Results of in vitro studies on the influence of itraconazole on mycelial transformation of 88 Candida albicans strains are presented. The drug influenced a number of cells capable to produce filaments. The number of those cells diminished gradually together with the increase of the drug concentration. The range of TI100 values was between 0.02 and 18.0 micrograms ml of medium. Mycelial transformation phenomenon can be applied for preliminary and rapid evaluation of Candida albicans strains sensitivity to itraconazole.     

Factors affecting the reduction of acetylene by Rhizobium-soybean cell associations in vitro

The acetylene reduction assay was used to measure presumed N₂-reducing activity in Rhizobium-soybean cell associations in vitro. No acetylene reduction was observed in liquid suspensions of these organisms, but cells plated onto an agar medium from a liquid suspension of Rhizobium and soybean cells exhibited acetylene-dependent production of ethylene after 7 to 14 days. Aggregates of soybean cells 0.5 to 2.0 mm in diameter were required for this activity. Decreasing oxygen from 0.20 atm to 0.10, 0.04, or 0.00 atm completely inhibited acetylene reduction. The presence of 2,4-dichlorophenoxyacetic acid or kinetin increased endogenous ethylene production and inhibited acetylene-dependent ethylene production. Acetylene reduction was observed with three out of four strains of R. japonicum tested, and three rhizobial strains, which produce root nodules on cowpeas but not soybeans, formed an association capable of acetylene-dependent ethylene production.     

Incidence of alginate-coding gene in carbapenem-resistant Pseudomonas aeruginosa strains

Pseudomonas aeruginosa rods are one of the most common isolated opportunistic nosocomial pathogens. Strains usually are capable to secret a capsule-like polysaccharide called alginate important for evasion of host defenses, especially during chronic pulmonary disease of patients with cystic fibrosis. Most genes for alginate biosynthesis and lysis are encoded by the operon. The aim of our study was to evaluate the incidence of algD sequence, generally use for alginate-coding gene detection, in 120 P. aeruginosa strains resistant to carbapenems. All isolates were obtained in the Department of Clinical Microbiology University Hospital no. 1 of dr A. Jurasz Collegium Medicum of L. Rydygier in Bydgoszcz Nicolaus Copernicus University in Toruń. Examined strains demonstrated resistance to carbenicillin (90,0%), ticarcillin (89,2%) and ticarcillin clavulanate (86,7%). All strains were susceptible to colistin. The majority of examined strains was susceptible to ceftazidime and cefepime (40,8% each) and norfloxacin (37,5%). Presence of algD gene - noted in 112 (93,3%) strains proves that not every strain is capable to produce alginate. It was also found out that differences in algD genes incidence in case of different clinical material that strains were isolated from were not statistically important.     

Far-ultraviolet sensitivity and photoreactivation of Hirsutella thompsonii

The far-ultraviolet (FUV; 200–300 nm) sensitivity of four pathotypes of Hirsutella thompsonii, representative of three separate taxonomic varieties of the species, was investigated. The UV inactivation curves for the four strains were indistinguishable. A mutant exhibiting enhanced conidiation derived from the HTF-72 strain was more FUV sensitive than the four wild type strains (fluence enhancement factor ? 1.5). All strains were capable of efficiently photoreactivating FUV damage by a process which appeared to enzymatic.     

An analysis of bacteriocins produced by lactic acid bacteria isolated from malted barley

AIMS: The aim of this study was to perform a detailed characterization of bacteriocins produced by lactic acid bacteria (LAB) isolated from malted barley. METHODS AND RESULTS: Bacteriocin activities produced by eight LAB, isolated from various types of malted barley, were purified to homogeneity by ammonium sulphate precipitation, cation exchange, hydrophobic interaction and reverse-phase liquid chromatography. Molecular mass analysis and N-terminal amino acid sequencing of the purified bacteriocins showed that four non-identical Lactobacillus sakei strains produced sakacin P, while four Leuconostoc mesenteroides strains were shown to produce bacteriocins highly similar or identical to leucocin A, leucocin C or mesenterocin Y105. Two of these bacteriocin-producing strains, Lb. sakei 5 and Leuc. mesenteroides 6, were shown to produce more than one bacteriocin. Lactobacillus sakei 5 produced sakacin P as well as two novel bacteriocins, which were termed sakacin 5X and sakacin 5T. The inhibitory spectrum of each purified bacteriocin was analysed and demonstrated that sakacin 5X was capable of inhibiting the widest range of beer spoilage organisms. CONCLUSION: All bacteriocins purified in this study were class II bacteriocins. Two of the bacteriocins have not been described previously in the literature while the remaining purified bacteriocins have been isolated from environments other than malted barley. SIGNIFICANCE AND IMPACT OF THE STUDY: This study represents a thorough analysis of bacteriocin-producing LAB from malt and demonstrates, for the first time, the variety of previously identified and novel inhibitory peptides produced by isolates from this environment. It also highlights the potential of these LAB cultures to be used as biological controlling agents in the brewing industry.     

Production of exotoxins by Aeromonas spp. at 5°C

The ability of 60 strains of Aeromonas to produce enterotoxin and haemolysin after cultivation at 5°C for 7–10 d was investigated. The strains were isolated from lamb meat, offal, carcasses and faeces, and had previously been tested for their ability to produce these exotoxins at 37°C. The results showed that some strains of Aeromonas hydrophila and A. sobria were capable of producing enterotoxin and haemolysin at 5°C, but none of the A. caviae strains tested produced these two factors. Of the 30 A. hydrophila strains investigated 25 and 27 were enterotoxigenic and haemolytic respectively. Likewise, of the 24 A. sobria strains investigated 16 and 18 were enterotoxigenic and haemolytic respectively. The results indicate that certain strains of Aeromonas species, in particular A. hydrophila and A. sobria , are of potential public health significance in meats stored at refrigeration temperature.     

Evaluation of biofilm production and prevalence of the icaD gene in methicillin-resistant and methicillin-susceptible Staphylococcus aureus strains isolated from patients with nosocomial infections and carriers

Staphylococcus aureus is one of the most important etiological agents responsible for healthcare-associated infections and is capable of producing many virulence factors including biofilm. The aim of the present study was to analyze the correlation between the presence of the icaD and icaA genes and the ability to produce biofilm in vitro in 302 methicillin-resistant (MRSA) and 268 methicillin-sensitive S. aureus (MSSA) strains isolated in the Provincial Hospital in Gdansk. Presence of the icaD and icaA genes was detected by PCR and the ability to produce biofilm in vitro was measured both spectrophotometrically and via Congo Red Agar plate culture methods. We found that 91% of MRSA strains harbored the icaD gene. Moreover, all icaD-negative strains were icaA-positive. Of MRSA and MSSA strains, 47% and 69%, respectively, produced biofilm in vitro. The level of consistency between the two applied phenotypic methods was 96%. Additionally, we found that strains with the same biofilm status may be present in asymptomatic carriers and cause infections.     

Oxygen does not directly regulate carotenoid biosynthesis in Rhodopseudomonas capsulata.

We examined the role of bacteriochlorophyll synthesis on the regulation of carotenoid synthesis in Rhodopseudomonas capsulata. Strains capable of making bacteriochlorophyll accumulated greater amounts of carotenoids under low oxygen than they did under high oxygen. However, strains unable to produce bacteriochlorophyll did not regulate their carotenoid production in response to changes in oxygen tension. This indicates that oxygen does not directly regulate carotenoid production.     

Differences in mesentericin secretion systems from two Leuconostoc strains

Leuconostoc mesenteroides Y105 and L. mesenteroides FR52 produce both mesentericin Y105 and B105, in equal amounts. The mesentericin operons of L. mesenteroides FR52 and Y105 which are involved in mesentericin Y105 and B105 production, were both sequenced and compared. Differences were limited to the two genes, mesD and mesE, which encode the dedicated transport system of mesentericin Y105. Analysis of mesentericin non-producing mutants and complementation experiments demonstrated that the major role of the membrane fusion protein, MesE, was in bacteriocin secretion for both strains. Moreover, the secretion machinery MesDE was demonstrated to be capable of transportation and maturation of the two pre-bacteriocins, mesentericin Y105 and B105. We also demonstrate that although MesDEs from strains Y105 and FR52 have significant sequence differences, both transporters were capable of assuring secretion of either bacteriocin.     

Production of volatile compounds in liquid cultures by six strains of coryneform bacteria

Summary The aromatic profiles of four strains of Brevibacterium linens, one strain of Brevibacterium sp. and one strain of Microbacterium sp. were determined with some pure cultures of these microorganisms in standard trypcase soy liquid medium, which enabled four of these six strains to produce flavour compounds of ripened cheese. Thirty-two flavour compounds were identified by gas chromatography and mass spectrometry. The identified flavour compounds included the following: fatty acids, alcohols, methylketones, sulphur compounds, aromatic compounds and a pyrazine. Some important differences were found among the six strains studied. The four strains of B. linens had similar flavour profiles. Their typical flavour was probably due to dimethyltrisulphide. The two other strains did not appear to produce this compound. Three strains produced significant amounts of the floral aromas phenylethanol and phenylpropanone.Offprint requests to: J.-M. Belin