Affinities offreshwater“Chantransia”stage algae(Rhodophyta)from China based on molecular and morphological analyses

Twelve putative"Chantransia"isolates were collected from six locations across Hubei,Shanxi,Guizhou,and Henan Provinces in China.Their morphological characters were evaluated via the Ward’s method of hierarchical cluster analysis in SPSS software to classify phylogenetic relationships among the isolates.The morphological data revealed that isolate HN31(called group"MALL")was distinct from the other specimens being macroscopic with large vegetative cells and monosporangia(>20μm in diameter).The 11 other isolates were grouped into three clusters,corresponding to the species Audouinella tenella,A.hermannii,and A.pygmaea.The morphological"Chantransia"stage of the species,reportedly belonging to the orders Batrachospermales,Thoreales,and the phylogenetically distant genus Audouinella,are very similar,resulting in the di fficulty to distinguish them based just on morphology.Therefore,molecular analysis of rbc L,UPA,and COI-5 P was conducted to infer the phylogenetic position of all isolates in this study.All"A.tenella"and"A.hermannii"sequences belong to order Batrachospermales,while the isolate HN31 was the"Chantransia"of Thorea hispida.The six other specimens varied morphologically,but they were within the circumscription of"A.pygmaea".All three molecular markers show that all"pygmaea"isolates also represent the"Chantransia"of T.hispida.Furthermore,results from this investigation proposed a new species—Sheathia qinyuanensis,corresponding to the isolates QY1 and QY2.

Performance and role of N-acyl-homoserine lactone(AHL)-based quorum sensing(QS) in aerobic granules

The present study investigated the relationship between N-acyl-homoserine lactone（AHL）-based quorum sensing（QS） and the physico-chemical properties of aerobic granules.Stable mature granules were observed in SBR2 and SBR3 with average diameters of 0.96,and1.49 mm,respectively. The sludge densities of aerobic granules in SBR2 and SBR3 were1.0246,and 1.0201 g/mL,respectively,which were higher than that of flocculent sludge in SBR1（1.0065 g/mL）. The results showed that the activity of AHL-based QS in SBR2 and SBR3 amounted to 2.4- and 2.1-fold induction,however,that in SBR1 with flocculent sludge was1.6-fold induction. In addition,the results also showed that the activity of AHL-based QS in the three reactors rose in the feast condition,and then dropped with the consumption of substrate. However,the activity of AHL-based QS in these three reactors recovered again in prolonged starvation. Furthermore,the results showed that the enhancement of AHL-based QS favored the extracellular polymeric substance production of microorganisms in activated sludge. Thus,it could be concluded that aerobic granules showed higher AHL-based QS than flocculent sludge,which resulted from the higher sludge density of aerobic granules than flocculent sludge. AHL-based QS was related to the metabolism energy in the feast condition; however,in prolonged starvation,microorganisms would emit more AHL-like molecules to protect themselves to resist starvation. Moreover,the enhancement of AHL-based QS favored the EPS component productivity of the microorganisms in activated sludge,which contributed to maintain the aerobic granular structure.

The biological effect of metal ions on the granulation of aerobic granular activated sludge

As a special biofilm structure,microbial attachment is believed to play an important role in the granulation of aerobic granular activated sludge（AGAS）.This experiment was to investigate the biological effect of Ca^2＋,Mg^2＋,Cu^2＋,Fe^2＋,Zn^2＋,and K＋which are the most common ions present in biological wastewater treatment systems,on the microbial attachment of AGAS and flocculent activated sludge（FAS）,from which AGAS is always derived,in order to provide a new strategy for the rapid cultivation and stability control of AGAS.The result showed that attachment biomass of AGAS was about 300%higher than that of FAS without the addition of metal ions.Different metal ions had different effects on the process of microbial attachment.FAS and AGAS reacted differently to the metal ions as well,and in fact,AGAS was more sensitive to the metal ions.Specifically,Ca^2＋,Mg^2＋,and K＋could increase the microbial attachment ability of both AGAS and FAS under appropriate concentrations,Cu^2＋,Fe^2＋,and Zn^2＋were also beneficial to the microbial attachment of FAS at low concentrations,but Cu^2＋,Fe^2＋,and Zn^2＋greatly inhibited the attachment process of AGAS even at extremely low concentrations.In addition,the acylated homoserine lactone（AHL）-based quorum sensing system,the content of extracellular polymeric substances and the relative hydrophobicity of the sludges were greatly influenced by metal ions.As all these parameters had close relationships with the microbial attachment process,the microbial attachment may be affected by changes of these parameters.