Project description:Anaerobic ammonium-oxidising (anammox) bacteria, members of the ‘Candidatus Brocadiaceae’ family, play an important role in the nitrogen cycle and are estimated to be responsible for about half of the oceanic nitrogen loss to the atmosphere. Anammox bacteria combine ammonium with nitrite and produce dinitrogen gas via the intermediates nitric oxide and hydrazine (anammox reaction) while nitrate is formed as a by-product. These reactions take place in a specialized, membrane-bound compartment called the anammoxosome. Therefore, the substrates ammonium, nitrite and product nitrate have to cross the outer-, cytoplasmic- and anammoxosome membranes to enter or exit the anammoxosome. The genomes of all anammox species harbour multiple copies of ammonium-, nitrite- and nitrate transporter genes. Here we investigated how the distinct genes for ammonium-, nitrite- and nitrate- transport were expressed during substrate limitation in membrane bioreactors. Transcriptome analysis of Kuenenia stuttgartiensis planktonic cells under ammonium-limitation showed that three of the seven ammonium transporter genes and one of the six nitrite transporter genes were significantly upregulated, while another ammonium and nitrite transporter gene were downregulated in nitrite limited growth conditions. The two nitrate transporters were expressed to similar levels in both conditions. In addition, genes encoding enzymes involved in the anammox reaction were differentially expressed, with those using nitrite as a substrate being upregulated under nitrite limited growth and those using ammonium as a substrate being upregulated during ammonium limitation. Taken together, these results give a first insight in the potential role of the multiple nutrient transporters in regulating transport of substrates and products in and out of the compartmentalized anammox cell.
Project description:Macrobrachium nipponense is one of the commonest species threatened by ambient superfluous nitrite. The mechanism of nitrite stress at the molecular level was studied using de novo RNA-Seq to explore the molecular pathways in M. nipponense exposed to the acute nitrite stress (26.05 mg/L nitrite-N) for 24h and the chronic nitrite stress (6.58 mg/L nitrite-N) for 21d. A total of 175.13 million reads were obtained and assembled into 58,871 unigenes with an average length of 1,028.7 bp and N50 of 1,294bp. 2,824 and 2,610 unigenes in the acute and chronic nitrite stress were significantly differentially expressed respectively. Based on the change in GO analysis and KEGG pathway analysis, pathways both in the acute and chronic nitrite stress were glycosphingolipid biosynthesis - ganglio series, alanine aspartate and glutamate metabolism, biotin metabolism and amino sugar and nucleotide sugar metabolism which revealed the commonly functional pathways in acute and chronic nitrite stress. The markedly altered pathways were divided into four sections of immunity, metabolism, cell and others. Immunity section contained the most pathways among the classifications as phagosome, folate biosynthesis, glycerolipid metabolism, glycine, serine and threonine metabolism, selenoamino acid metabolism, cysteine and methionine metabolism, amino sugar and nucleotide sugar metabolism and taurine and hypotaurine metabolism in the acute nitrite stress and lysosome, alanine, aspartate and glutamate metabolism, arginine and proline metabolism, glycosaminoglycan degradation and amino sugar and nucleotide sugar metabolism in the chronic nitrite stress. This is the first report of whole molecular responses of M. nipponense under acute and chronic nitrite stress through de novo transcriptome sequencing. The findings of this study will further promote the understanding of the underlying molecular mechanisms of the nitrite stress for crustacean species.
Project description:Four Fe(II) concentrations (0.03, 0.09, 0.12 & 0.75 mM) were tested to investigate the stimulation and inhibition effects of ferrous iron on anammox bacterial activity. RNAs were extracted from the cultures, and the synthesized cDNAs by reverse transcription were used to carry out GeoChip analysis, by which the functional communities and expression level differences in functional genes under different Fe(II) concentrations conditions were obtained, and the response of anammox bacteria to Fe(II) stimulation and inhibition are speculated.
Project description:The antimicrobial action of the curing agent NaNO2, which is added as a preservative to raw meat products, depends on its conversion to nitric oxide and other reactive nitrogen species under acidic conditions. In this study, we applied RNA-sequencing to analyze the acidified NaNO2 shock and adaptive response of Salmonella Typhimurium, a frequent contaminant in raw meat. Upon a 10 minute exposure to 150 mg/l NaNO2 in LB pH 5.5 acidified with lactic acid, genes involved in nitrosative stress protection together with several other stress related genes were induced. To the contrary, genes involved in translation, transcription, replication and motility were down-regulated. Induction of stress tolerance and reduction of cell proliferation obviously promote survival under harsh acidified NaNO2 stress. The subsequent adaptive response was characterized by up-regulation of NsrR-regulated genes and iron-uptake systems and down-regulation of genes involved in anaerobic respiratory pathways. Strikingly, amino acid decarboxylase systems, which contribute to acid tolerance, displayed increased transcript levels in response to acidified NaNO2. The induction of systems known to be involved in acid resistance indicates a nitrite mediated increase of acid stress.
Project description:The antimicrobial action of the curing agent NaNO2, which is added as a preservative to raw meat products, depends on its conversion to nitric oxide and other reactive nitrogen species under acidic conditions. In this study, we applied RNA-sequencing to analyze the acidified NaNO2 shock and adaptive response of Salmonella Typhimurium, a frequent contaminant in raw meat. Upon a 10 minute exposure to 150 mg/l NaNO2 in LB pH 5.5 acidified with lactic acid, genes involved in nitrosative stress protection together with several other stress related genes were induced. To the contrary, genes involved in translation, transcription, replication and motility were down-regulated. Induction of stress tolerance and reduction of cell proliferation obviously promote survival under harsh acidified NaNO2 stress. The subsequent adaptive response was characterized by up-regulation of NsrR-regulated genes and iron-uptake systems and down-regulation of genes involved in anaerobic respiratory pathways. Strikingly, amino acid decarboxylase systems, which contribute to acid tolerance, displayed increased transcript levels in response to acidified NaNO2. The induction of systems known to be involved in acid resistance indicates a nitrite mediated increase of acid stress. Transcriptome of Salmonella Typhimurium 14028, treated at OD600 = 0.80-0.85 with 150 mg/l NaNO2 (acidified by lactic acid in the growth medium) for 10 min (shock response) or until an OD600 = 1.45-1.55 is reached (1.5 - 2.0 h, adaptation response), was compared to respective control cultures without NaNO2. Amplified cDNA libraries for sequencing on the SOLiD 5500xl system were prepared from one culture per condition.
Project description:The physiology of the planctomycetal anammox bacteria makes them particularly special because they share features with all three domains of life. Anammox bacteria have been reported recently to produce surface-layer proteins, which represent the outermost layer and provide structure, shape and protection under extreme conditions. Furthermore, we report on the unique cell surface-layer glycosylation of the anammox bacterium Ca. Kuenenia stuttgartiensis as revealed by a newly established glycoproteomics approach. This approach enables untargeted exploration of prokaryotic protein glycosylation from (high-resolution) shotgun proteomics data directly.