Rod Bacteria Research Articles

Potential Probiotic Lactic Acid Bacteria of Human Origin Induce Antiproliferation of Colon Cancer Cells via Synergic Actions in Adhesion to Cancer Cells and Short-Chain Fatty Acid Bioproduction

The activities and modes of probiotic action of lactic acid bacteria isolated from infant feces were investigated for alternative application in the prevention and biotherapy of colon cancer. From a total of 81 isolates of Gram-positive rod and cocci bacteria obtained from healthy infants, only 15 isolates had the probiotic criteria which included growth inhibition against eight food-borne pathogens, no blood hemolysis, and tolerance to gastrointestinal tract properties such as pH 2.5 and 0.3 % bile salt. Four probiotic bacteria showed antiproliferation of colon cancer cells with the use of MTT and Trypan blue exclusion assay at the rates of 17-35 %. Through comparison of probiotic 16S rRNA sequences, they were identified as Pediococcus pentosaceus FP3, Lactobacillus salivarius FP25, L. salivarius FP35, and Enterococcus faecium FP51. Finding the mechanism of proliferative inhibition of colon cancer cells in this study indicated synergic induction by probiotic bacteria directly adhered to these cancer cells and triggered the bioproduction of short-chain fatty acids, mainly butyric and propionic acids. This study suggested that the use of these probiotics may be suitable as an alternative bioprophylactic and biotherapeutic strategy for colon cancer.

Microbial contamination of contact lens storage cases and domestic tap water of contact lens wearers

Contact lenses have been widely used as an alternative to spectacles both in developed and developing countries. However, under certain circumstances, adverse responses can occur during contact lens wear and several microorganisms--including bacteria, fungi, and free living amoebae--can cause several eye infections in wearers. Extended wear of contact lenses is the major risk factor of eye infections such as microbial keratitis, besides contaminated contact lens storage case, contaminated lens care solutions, and inaccurate contact lens handling. In this study, we collected contact lens storage case and domestic tap water samples from 50 asymptomatic contact lens wearers. We determined that total aerobic mesophilic bacteria were isolated in 45 (90 %), Gram negative rod bacteria were isolated in 20 (40 %), Pseudomonas spp. were isolated in 2 (4 %) and fungi were isolated in 18 (36 %) out of 50 contact lens storage cases. Free living amoebae were not detected in investigated contact lens storage cases. At the same time, out of 50, total aerobic mesophilic bacteria were isolated in 34 (68 %), fungi were isolated in 15 (30 %) and free living amoebae were isolated in 15 (30 %) domestic tap water samples. No Gram-negative rod bacteria and Pseudomonas spp. were detected in investigated water samples. Two contact lens case samples and two tap water samples were excluded from the analysis for Pseudomonas spp. for technical reasons. According to our findings, inadequate contact lens maintenance during lens wear may result in the contamination of contact lens storage cases. This situation can lead to severe eye infections in contact lens wearers over time.

Influence of electrode material and electrode distance on bioelectricity production from sago‐processing wastewater using microbial fuel cell

Microbial fuel cells (MFC) are hybrid bioelectrochemical devices, which generate electrical energy through the oxidation of organic matter catalyzed by bacteria. In this research, the influence of electrode distance and different electrode materials on power production and chemical oxygen demand (COD) removal using raw sago‐processing wastewater were studied. Effect of electrode distance on MFC performance was carried out by varying it as 10, 12 and 15 cm. This study revealed that electrode distance of 10 cm resulted in increased power production with a voltage of 900 mV (millivolts), current of 9.0 mA (milliamps) at 100 Ω and COD removal of 94% compared to electrode distance of 12 and 15 cm. Graphite electrodes were good in power production compared to aluminum, stainless steel, and iron electrodes. Biofilm examination on the anode showed the presence of gram‐negative rod (E. coli) bacteria which might have contributed for power production. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 390‐395, 2013

Isolation, identification and pathogenicity of Listonella anguillarum from diseased cultured Sebastes schlegelii

Sebastes schlegelii is an important economic fish cultured in North China.In recent years,S.schlegelii aquaculture has developed rapidly along the northern coast of China.The expansion and intensification of S.schlegelii farming has led to the occurrence of some diseases.In August 2011,an epizootic occurred among cultured S.schlegelii in a cage culture farm in Qingdao,which caused cumulative mortality rate 30%.To make certain the causative pathogen,we studied the etiology and virulence of S.schlegelii so as to provide basic data for the farming industry of S.schlegelii.In this study,we used the morphological,physiological and biochemical methods to identify the isolated bacterium.Meanwhile,to ensure the results accurately,the phylogenetic analyses were also used.A dominant bacterium strain SS-1 was isolated from the skin,gill,liver,spleen,kidney of the diseased S.schlegelii.Artificial infection test with intramuscular injection method proved that the median lethal concentration(LC50) value of bacterium strain SS-1 in S.schlegelii was 9.6×106CFU/mL.This bacterium could cause severe infections in several tissues and organs of the fish.The results of morphological,physiological biochemical characteristics tests showed that strain SS-1 was gran-negative,rod bacteria,polar flagellum,and the results of oxidase,contact enzyme,nitrate reduction,producing indol,V-P test and arginine digydrolase test were positive;producing H2S test was negative.The morphological,physiological biochemical characteristics indicated that SS-1 could be identified as Listonella anguillarum.The sequence analysis of 16S rRNA gene of strain SS-1 was identical with L.anguillarum and the homogeneity is 99%.This paper reported for the first time that L.anguillarum caused the disease of S.schlegelii in China,which will provide reference in fish health management and disease control.

A Case of Bacteremia Due toMicrobacterium oleivoransIdentified by 16S rRNA Sequencing Analysis

Microbacterium oleivorans is a gram-positive, coryneform rod bacterium. The pathogenic potential of the Microbacterium species has recently been reported to be increasing. Microbacterium comprises approximately 50 species. The differences in regards to the biochemical characteristics of Microbacterium species are unclear, and is why molecular investigations (e.g., using 16S rRNA gene sequencing) are the best method to identify the species. We report a case of bacteremia that was caused by Microbacterium oleivorans in a 4-year-old boy, who had no specific medical history. This represents the first report of M. oleivorans bacteremia in Korea. (Korean J Clin Microbiol 2012;15:110-113)

A Case ofBacillus licheniformisSpondylitis and Bacteremia in a Patient with Lung Cancer

Bacillus licheniformis is an aerobic, gram-positive, spore-forming rod bacteria usually found in the environment. Infections with B. licheniformis are rare and usually associated with an immunocompromised state, trauma, and an indwelling catheter. We report a case of bacteremic B. licheniformis spondylitis following vertebroplasty in a patient with lung cancer.

Isolation of equol-producing bacterium to realize chemoprevention of prostate cancer.

1565 Background: Equol is known to possess a stronger estrogenic activity than the other soy isoflavone derivatives and has been reported to prevent prostate cancer. Equol is exclusively produced from daidzein by intestinal bacteria, which, however, does not happen in all people. In a case-control study, the percentage of non-equol producers was significantly higher in patients with prostate cancer than in healthy individuals (Akaza et al. 2002). Therefore, controlling the certain intestinal inhabitants may be a promising strategy for the primary prevention of prostate cancer. However, details of equol-producing bacteria in the human gut have not been clarified. Methods: The suspensions of a fresh stool sample from an equol producer were incubated in various medium under anaerobic condition at 37°C for 24 h. The 7th passage of the culture supplemented with sorbose was used as the source of isolation. An isolated strain was confirmed to have the ability to convert daidzein to equol by HPLC, and was designated strain NATTS. The 16S rRNA gene sequence of strain NATTS was analyzed, and a specific primer set for strain NATTS and related strains was designed. The population levels of the species in 40 healthy Japanese adults were enumerated by RT-qPCR (Matsuda et al. 2009). Results: Several kinds of carbohydrates were found to enhance equol production from daidzein in an in vitro human fecal culture. Sorbose, one of the most effective carbohydrates, was used as the carbohydrate source for isolating a strain with ability to convert daidzein to equol in human fecal culture; Strain NATTS, a Gram-positive, non-spore-forming rod bacterium with high ability to convert daidzein to equol was found to belong to the genus Slackia by 16S rRNA sequence based analysis, and the prevalence of the Slackia sp. in Japanese adults was found to be 40% at a mean population level of 106 cells per gram of feces. Conclusions: An equol-producing bacterium, Slackiasp. strain NATTS, with a high equol-producing activity was isolated from a human fecal culture by the addition of prebiotic sorbose. The Slackia sp. strain NATTS and related strains were found to have a high prevalence in Japanese adult intestine.

The morbidity of Clostridium difficile infection after elective colonic resection—results from a national population database

Background Clostridium difficile (CD), a gram-positive rod bacterium, resides normally within the human colon. Antibiotic treatment alters normal colonic flora, potentiating abnormal overgrowth of CD. Methods This study examined the 2004 to 2006 Nationwide Inpatient Sample to determine outcomes of CD colitis after 695,010 elective colonic resections. Results CD infection, occurring in 1.4% of patients, was associated with higher pulmonary (12.1% vs 6.4%) and gastrointestinal (12.8% vs 10.5%) complications as well as an increased length of stay (22.6 vs 10.9 days) and mortality (16.2% vs 4.9%; all P < .001). CD colitis patients more frequently held Medicare insurance (68% vs 51%) and underwent small segmental colonic resection as opposed to a defined anatomic resection (20.0% vs 9.9%; P < .001). An underlying diagnosis of colon cancer was associated with a lower incidence of CD colitis (odds ratio, .71; 95% confidence interval, .59–.84; P < .001). Conclusions CD colitis is associated with worse outcomes after elective colonic resection.

Enrichment of Anammox bacteria in seed sludges from different wastewater treating processes and start-up of Anammox process

Three seed sludges (sludge A, B and C) were collected from various wastewater treatment processes. Then they were inoculated in Reactor A, B and C in parallel. After 67days of operation, only Reactor A successfully started up the Anaerobic ammonia oxidation (Anammox) process, while the other two reactors failed. The Anammox activity was observed within 49days and a final nitrogen removal rate of 0.19g NH4+–NL−1d−1 and 0.21g NO2−–NL−1d−1 was achieved after 95days. In Reactor A, Fluorescence in situ hybridization (FISH) analysis confirmed that Anammox bacteria became the dominant population on day 90, and Scanning electron microscope (SEM) observation also showed that short rod and spherical bacteria predominated in the cultivated sludge. FISH analysis also disclosed that sludge A had aboriginal Anammox bacteria but the other two have no signal of Anammox bacteria. From a new micro-ecological viewpoint, the wastewater treating process, which sludge A was taken from, could provide Anammox ecological niche, but the other two processes could not. The results indicated that selection of the seed sludge from the special wastewater treating process providing Anammox ecological niches made the Anammox start-up more effectively and quickly.

Occurrence of Helicobacter pullorum in turkeys

In order to investigate the occurrence of Helicobacter pullorum in turkeys, caecum contents collected at the slaughterhouse from 55 animals intensively reared in 11 farms were sampled. Gram-negative curved rod bacteria were isolated by a modified Steele and McDermott filter technique and further identified as H. pullorum by polymerase chain reaction (PCR). Eleven and 31 isolates, randomly selected from each positive farm, underwent phenotypic (biochemical and antibiotic susceptibility tests) and genotypic characterization (PFGE and AFLP analysis), respectively. Forty-two out of 55 animals (76.4%) and all the 11 farms sampled were positive for H. pullorum. Isolates showed similar biochemical characteristics and whole cell protein profiles but showed a high degree of genetic heterogeneity. Ten out of 11 isolates were resistant to one or more antibiotics with erythromycin, ciprofloxacin and nalidixic acid resistance being the most frequently detected. This is the first description of H. pullorum in turkeys. H. pullorum is a frequent intestinal colonizer in turkeys; therefore, attention should be given to clarify the food-borne risk linked to carcass contamination. Antibiotic resistance is a concern since high values of resistance rates were observed.

Cutaneous Infectious Granuloma Caused by Phenylobacterium in an Adult with Myelodysplastic Syndrome

Painful granulomatous lesions appeared on the face of a 36-year-old man with myelodysplastic syndrome. Skin biopsy revealed chronic inflammatory granuloma. Bacterial cultures of the lesions and blood indicated the same unknown Gram-negative rod bacterium. The 16S ribosomal RNA sequence of the unknown bacterium yielded Phenylobacterium. Thus, we diagnosed cutaneous infectious granuloma caused by Phenylobacterium and myelodysplastic syndrome/refractory cytopenia with multi-lineage dysplasia. After treatment with combined antibacterials that were selected based on the tests for drug sensitivity, the lesions disappeared with only scars remaining and without any signs of relapse after 1 year. This is the first case report of cutaneous infectious granuloma caused by Phenylobacterium.

Isolation and identification of cultivable lactic acid bacteria in traditional fermented milk of Tibet in China

One hundred and seventy‐one strains of lactic acid bacteria were isolated from 44 traditional fermented milk samples from different region of Tibet. Among these samples, the concentrations of lactic acid bacteria varied from 10 5 to 10 9 colony forming unit/mL. The ratio of rod bacteria (71.3%) was higher than that of cocci (28.7%), and was considered to be the major population. Lactobacillus fermentum (31%) and Lactobacillus casei (28%) were the most predominant species among all these isolates. This study systematically analysed the microbial composition of traditional fermented milk in China, which may become a valuable source for further starter selection.

Effect of Mentha longifolia L. ssp longifolia essential oil on the morphology of four pathogenic bacteria visualized by atomic force microscopy

The chemical composition and the antibacterial activity of the essential oil ofMentha longifolia L. ssp longifolia are being investigated in the present work. The minimal inhibitory concentration (MIC) of this oil against four gram+ and gram- reference bacteria including Salmonella typhimurium LT2, Escherichia coli ATCC 35218, Microccus luteus NCIMB 8166 and Staphylococcus aureusATCC 25923 was used to study the morphological alteration of bacterial wall cell visualized by atomic force microscopy (AFM). The chemical analysis of the essential oil showed the presence of 34 compounds. The most important ones were: menthol (32.51%), menthone (20.71%), pulegone (17.76%), 1,8-cineole (5.61%), terpineol-4 (4.87%) and piperitone (2.16%). The MIC for bacteria ranged from 0.19 to 1.56 mg/ml. We found that M. longifolia (Menthol chemotype) has a high antibacterial effect. Cell wall of the tested bacteria was damaged at MIC concentrations. This susceptibility is more accentuated in S.typhimurium and E. coli (rod bacteria), whereas the damage is less important in coccoid bacteria (S. aureus and M. luteus). Key words: Mentha longifolia, essential oil, Staphylococcus aureus, Microccus luteus, Escherichia coli, Salmonella typhimurium, cell morphology, atomic force microscope

A rapid method for the isolation of eicosapentaenoic acid-producing marine bacteria

Bacterial production of long chain polyunsaturated fatty acids (LC-PUFAs) is a promising biotechnological approach for the mass production of these valuable compounds, but extensive screening is currently needed to select a strain that meets industrial requirements. A method was developed for the rapid screening and isolation of eicosapentaenoic acid (EPA)-producing marine bacteria from mixed cultures using the dye 2,3,5-triphenyltetrazolium chloride (TTC). The method was first validated using two bacteria from the Shewanella genus, S. gelidimarina (known to contain EPA) and S. fidelis (known not to contain EPA), and subsequently applied to a range of bacterial samples collected from seven randomly selected New Zealand fish species. By incorporating TTC in both solid and liquid state fermentation treatments, a clear association between the reduction of TTC to the red-coloured triphenyl formazan (TF) and the presence of EPA within Gram-negative bacteria was confirmed. Incubation in 0.1% w/v TTC was optimal for colour response and cell growth in agar plates and liquid cultures. Bacteria that produce EPA reduced TTC to TF, but a number of non-EPA-producing bacteria also showed this capacity. By conducting a subsequent Gram staining, all EPA-producing strains were revealed to be G (−) rod bacteria while the non-producing ones were all G (+) cocci. The fatty acid methyl esters of the isolated bacteria that reduced TTC to TF were analysed using gas chromatography–mass spectrometry and the content of EPA was confirmed by gas chromatography. From a pool of 2.0 × 10 8 CFU/ml, this method allowed the rapid isolation of 16 bacteria capable of producing EPA. This new approach significantly reduces the number of samples submitted for GC analysis and therefore the time, effort and cost of screening and isolating strains of EPA-producing marine bacteria.

First Report of "Candidatus Liberibacter psyllaurous" (synonym "Ca. L. solanacearum") Associated with 'Tomato Vein-Greening' and 'Tomato Psyllid Yellows' Diseases in Commercial Greenhouses in Arizona.

During the winter of 2006-2007, plants in commercial tomato greenhouses (GH-1 and GH-2; total 320 acres [129.5 ha]) in Arizona were infested with the potato psyllid Bactericera cockerelli (Sulc) and more than 60% and ~20% of the plants, respectively, exhibited leaf curling, chlorosis, and shortened internodes. In addition, some plants in GH-1 developed an unusual 'vein-greening' phenotype. Nucleic acids were isolated from 10 symptomatic and three asymptomatic plants from each greenhouse. PCR primers designed to amplify a phytoplasma-like 16S rDNA (850 bp) yielded the expected size product from GH-1 samples, whereas samples from GH-2 and the asymptomatic samples from both greenhouses did not. Several 16S rDNA PCR products (3 of 60) when cloned and sequenced, surprisingly shared 97% homology with 'Candidatus Liberibacter asiaticus' (GenBank No. GQ926917). PCR primers PSY680F 5'-GTTCGGAATAACTGGGCGTA-3' and PSY1R 5'-CCCATAAGGGCCATGAGGACT-3', based on the resultant 16S rDNA sequences, were used to amplify a 680-bp fragment from plant DNA extracts and psyllid lysates (1). A robust PCR product (~680 bp) was obtained from 10 of 10 GH-1 plant extracts (GQ926918) and from a GH-1-derived psyllid colony (28 of 35 adults) (GQ926919) and the tomato plants on which they were reared. In contrast, no 680-bp product was obtained from GH-1 asymptomatic plants (0 of 3), GH-2 plants (0 of 10 symptomatic; 0 of 3 asymptomatic), GH-2-derived psyllid colonies (0 of 35 adults), or psyllid colony tomato plants (data not shown). At least three 680-bp amplicons for each sample type were cloned and 8 to 10 inserts were sequenced for each. BLAST analysis revealed that all 680-bp sequences shared 99 to 100% nt identity with the analogous 16SrDNA from "Ca. Liberibacter psyllaurous" (2) and synonym "Ca. L. solanacearum" (3). A second molecular marker was obtained with the 1611F and 480R primers (2) to amplify the 16SrDNA-23S-ITS (980 bp) from >3 plant extracts and psyllid lysates that tested positive for liberibacter. Clustal W alignment of the 16S-23S-ITS sequences from GH-1 original tomato plants and psyllid colony plants (GQ926920) and psyllids (GQ926921) indicated they were 100% identical to each other and BLAST analysis indicated 99 to 100% shared identity with "Ca. L. psyllaurous" (EU812558) (synonym "Ca. L. solanacearum"). Transmission electron microscopy examination of GH-1 and GH-2 psyllids revealed rod and pleomorphic-shaped bacteria (0.5 to 2.0+ μm) at the brain-salivary gland interface in psyllids from the GH-1 liberibacter-positive colony. No such bacteria were observed in GH-2 liberibacter-negative psyllids. These results support an etiological role of a new liberibacter spp. in the development of the 'vein-greening' symptom phenotype. In contrast, the GH-2 'yellows' phenotype is reminiscent of 'psyllid toxicity' in tomato colonized by B. cockerelli (4). To our knowledge, this is the first report of distinct psyllid-associated diseases in greenhouse tomato in Arizona, one associated with a new 'Ca. Liberibacter' spp., manifest as 'vein-greening' disease, and the other associated with psyllid feeding, in which liberibacter is undetectable in plants and psyllids, and is manifest as the 'tomato psyllid yellows' disease.

Isolation and characterization of the equol-producing bacterium Slackia sp. strain NATTS

Several kinds of carbohydrates such as sorbose, adonitol, and melezitose were found to enhance equol production from daidzein in an in vitro human fecal culture. Sorbose, one of the most effective carbohydrates, was used as a carbohydrate source for isolating the NATTS strain, which was a Gram-positive, non-spore-forming rod bacterium with high ability to convert daidzein to equol isolated from the 7th maintenance culture. The strain was found to belong to the genus Slackia family Coriobacteriaceae by 16S rRNA sequence-based analysis, and the prevalence of the Slackia sp. in Japanese adults was examined by reverse transcription-quantitative PCR (RT-qPCR), which was found to be 40% at a mean population level of 10(6) cells per gram of feces.

Update on pertussis in children

Pertussis (or whooping cough) is a frequent and important infectious disease of the respiratory tract, mainly caused by the Gram-negative rod bacterium Bordetella pertussis. Although it is frequently believed that pertussis is exclusively a ‘childhood disease’, in reality it occurs at any age but is most serious in young infants. Adults are the main reservoir for B. pertussis today and pertussis remains an endemic disease worldwide despite the availability of comprehensive immunization programs that primarily target the pediatric population. There are many reasons for these, and these include incomplete immunity following natural infection as well as immunization and waning immunity over time. Manifestations of B. pertussis infections vary by magnitude of the bacterial inoculum, age, immune status and probably further yet unidentified individual factors. They can range from asymptomatic, apnea and uncharacteristic cough to typical coughing spells with posttussive phlegm and/or vomiting, and duration also varies between a few days and several months. Since antibacterial treatment of pertussis is generally ineffective as it usually sets in too late, the main focus should be on the prevention of pertussis by immunization. This apparently requires more than immunization of children – that is, expanding routine immunization into adolescence and adulthood.

IDENTIFICATION OF PROTEINS INVOLVED IN INFECTIVITY AND ENTEROTOXIN PRODUCTION IN ENTEROBACTER SAKAZAKII

ABSTRACTEnterobacter sakazakii is a gram‐negative rod bacterium that was formerly known as “yellow‐pigmented Enterobacter cloacae” until 1980. It is an emerging opportunistic pathogen associated with bacterial meningitis in immunocompromised neonates who ingested contaminated powdered infant formula. In several E. sakazakii‐related outbreaks and sporadic cases, powdered infant formula was epidemiologically or microbiologically established as the source of infection. The International Commission on Microbiological Specifications for Foods has ranked E. sakazakii as a “severe hazard for restricted populations.” However, the organism was isolated at very low levels from commercial powdered infant formula and dry environmental samples collected from infant formula factories. In most cases, the contamination did not exceed 1 cfu per 100 g. Progress in understanding the epidemiology of E. sakazakii outbreaks and instituting effective control measures has been poor to date. To clarify the mechanisms involved in infectivity and enterotoxin production, we performed two‐dimensional gel electrophoresis (2‐DE) coupled with matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry and isotope‐coded affinity tags (ICATs)‐LC ‐MS to identify and quantify differences in protein expression between the E. sakazakii strains. We found 23 spots in 2‐DE and 37 proteins in ICAT analysis that were differentially expressed in E. sakazakii. These two methods gave us closely related but different information, suggesting that the two methods are complementary or at least supplementary.PRACTICAL APPLICATIONS Enterobacter sakazakii has been implicated in meningitis or enteritis with 20% to &gt;50% mortality of infants who contract the disease. Our research has been used in verification of Enterobacter sakazakii isolated from infant formula and other milk and milk related foods. We have established standard maps of two Enterobacter sakazakii strains which were isolated from infant formula. Through appearance or absence of specific spots and their isoelectric point or molecular weight comparison, a two dimensional electrophoresis standard map can be developed and used as a powerful tool to differentiate Enterobacter sakazakii from other Enterobacteriaceae. This offers microbiologists powerful tools for Enterobacter sakazakii detection and provides more basic information to investigate the pathogenesis of Enterobacter sakazakii and contamination sources in infant formula production.

Quantitative fluorescent in-situ hybridization: a hypothesized competition mode between two dominant bacteria groups in hydrogen-producing anaerobic sludge processes

Two hydrogen-producing continuous flow stirred tank reactors (CSTRs) fed respectively with glucose and sucrose were investigated by polymerase chain reaction-denatured gradient gel electrophoresis (PCR-DGGE) and fluorescent in-situ hybridization (FISH). The substrate was fed in a continuous mode decreased from hydraulic retention time (HRT) 10 hours to 6, 5, 4, 3, and 2 hours. Quantitative fluorescent in-situ hybridization (FISH) observations further demonstrated that two morphotypes of bacteria dominated both microbial communities. One was long rod bacteria which can be targeted either by Chis150 probe designed to hybridize the gram positive low G + C bacteria or the specific oligonucleotide probe Lg10-6. The probe Lg10-6, affiliated with Clostridium pasteurianum, was designed and then checked with other reference organisms. The other type, unknown group, which cannot be detected by Chis150 was curved rod bacteria. Notably, the population ratios of the two predominant groups reflected the different operational performance of the two reactors, such as hydrogen producing rates, substrate turnover rates and metabolites compositions. Therefore, a competition mode of the two dominant bacteria groups was hypothesized. In the study, 16S rRNA-based gene library of hydrogen-producing microbial communities was established. The efficiency of hydrogen yields was correlated with substrates (glucose or sucrose), HRT, metabolites compositions (acetate, propionate, butyrate and ethanol), thermal pre-treatment (seed biomass was heated at 100 degrees C for 45 minutes), and microbial communities in the bioreactor, not sludge sources (municipal sewage sludge, alcohol-processing sludge, or bean-processing sludge). The designed specific oligonucleotide probe Lg10-6 also provides us a useful and fast molecular tool to screen hydrogen-producing microbial communities in the future research.

Anin vitro evaluation of the interactions ofLegionella pneumophila serogroups 2 to 14 strains with other bacteria in the same habitat

The aim of the present study is to determinein vitro inhibitory and/or stimulatory effects of different bacteria on concomitantLegio nella pneumophila. The interactions betweenLegionella and other bacteria were investigated by using bacteria culture and cell-free supernatants (CFSs) on Buffered Charcoal Yeast Extract agar (BCYEA) and/or in BCYEA lacking L-cysteine. Additionally, CFSs of non-Legionella bacteria that possess inhibitory effect onL. pneumophila were characterised using enzyme and heat treatments. The inhibition ratio of the CFSs and the cultures of Gram-negative rod bacteria (GNRB) and Gram-positive rod bacteria (GPRB) on the growth ofL. pneumophila strains were 26–47% and 33–67%, respectively, on BCYEA. It was detected that the cultures ofAeromonas hydrophila, Aeromonas spp. strain andBacillus pumilus stimulated the growth of one of the investigatedL. pneumophila strains, but their CFSs did not show any stimulatory effect. The results indicated that growth and multiplication of legionellae could be affected by different bacteria sharing the same habitat and the level of this effect varies among the species. To our knowledge, this is the first study which determined the inhibitory effects ofB. pumilus andBrevibacillus brevis againstLegionella. The biologically active substances produced by the bacteria could play an important role in the control ofL. pneumophila. This phenomenon may be used an alternative approach for controlling legionellae in man-made environments.