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Denitratation (nitrite produced from nitrate), has the potential applications in wastewater treatment by combining with ANAMMOX process. The occurrence of denitratation has been shown to be effected qualitatively by various parameters in the environment. A more quantitative understanding can be obtained using enrichment cultures in lab-scale experiments, yet information on the enrichment of functional microorganisms responsible for denitratation is lacking. In this study, a stable denitratation-dominated culture was obtained from methylotrophic denitrifying culture. The results showed that, besides the substitution of acetate for methanol, the lasting starvation following saturation of electron donor was another pivotal selection pressure that favored the growth of denitratating bacteria, which was supported by the distinctive physiological strategy involving the higher growth rate combining with larger poly-hydroxybutyrate (PHB) accumulation at sufficient electron donor situation and then manage the stress of electron donor starvation by consumpiton of the PHB. High-throughput 16S rRNA gene sequencing analysis indicated that non-methylotrophic Halomonas campisalis (48.1 %) and Halomonas campaniensis (30.4 %) dominated in the denitratating community. Moreover the denitratation was driven by the nitrate inhibiting the nirS transcription in the Halomonas species.

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The neutral sphingomyelinase (nSMase) 1 homologue gene LsSMase was cloned from Laodelphax striatellus, a direct sap-sucker and virus vector of gramineous plants, and expressed via a Bac to Bac baculovirus expression system. The LsSMase-enhanced green fluorescent protein fusion protein was located in the endoplasmic reticulum in a similar manner to mammalian nSMase 1. The biochemical properties of LsSMase were determined in detail. The optimal pH and temperature for recombinant LsSMase were 8 and 37 °C, respectively. LsSMase was an Mg or Mn dependent enzyme, but different concentration of each were needed. The activity of LsSMase was significantly stimulated by Ethylene glycol bis(2-aminoethyl ether)tetraacetic acid (EGTA), whereas it was inhibited by ethylenediaminetetraacetic acid. Millimolar concentrations of Zn completely inhibited LsSMase. The reducing agents dithiothreitol and β-mercaptoethanol varied in their effects on activity. Phospholipids were not found to stimulate LsSMase.