Aerobic denitrification of oligotrophic source water driven by reduced metal manganese.

The lack of organic electron donors limits the potential utility of aerobic denitrification in treatment of oligotrophic source water. Here, reduced manganese (Mn) was used as an inorganic electron donor to improve the denitrification of oligotrophic source water under the high dissolved oxygen condition (7-9 mg L-1). Over 30 days, the total nitrogen removed by the treatment with reduced Mn was 76.21 ± 2.11% (maximum), substantially higher than that of the control treatment, which was 41.48 ± 2.33%. Furthermore, the addition of Mn resulted in the directional evolution of the microbial community. Water samples with Mn added showed a higher abundance of Limnohabitans, the dominant denitrifying genus, reaching 51.02%, 36.79%, and 20.19% (with 30, 50, and 70 g Mn, respectively), versus only 5.54% in the control. In biofilm, Mn promoted Hydrogenophaga and Brevundimonas growth while Pseudarthrobacter growth was promoted by 30 and 50 g Mn, but inhibited by 70 g Mn. This study demonstrates an improved performance in aerobic denitrification of water sources through the use of inorganic electron donors.

The complete chloroplast genome of Cuscuta australis R. Br. (Convolvulaceae) and its phylogenetic implication.

The genus Cuscuta (Convolvulaceae) is an annual parasitic twining herb. There are about 200 species in this genus, which are widely distributed in tropical and subtropical areas. Cuscuta is mainly parasitic on crops bringing significant losses to the production of agriculture. Furthermore, dried seeds of C. chinensis and C. australis are used as a Chinese traditional herbal medicine. Despite the importance of Cuscuta species, it is difficult to distinguish these plants by the naked eye. Moreover, plastid sequence information available for Cuscuta species is limited. In this study, the complete chloroplast (cp) genome sequence of C. australis was determined using next-generation sequencing. The entire cp genome was determined to be 85,263 bp in length. It contained large single-copy (LSC) and small single-copy (SSC) regions of 50,384 and 6727 bp, respectively, which were separated by a pair of 14,076 bp inverted repeat (IR) regions. The genome contained 98 genes, including 61 protein-coding genes, 29 tRNA genes, and 4 rRNA genes. The overall GC content of the genome is 37.8%. A phylogenetic tree reconstructed by 26 chloroplast genomes reveals that C. australis is most related with Cuscuta pentagona in Convolvulaceae, with bootstrap support values of 100%.