Distribution, Diversity And Degradation Characteristics Of DMSP- Consuming Bacteria In The Seawater Of The Yellow Sea And The East China Sea

The distribution, diversity, and degradation characteristics of dimethylsulfoniopropionate (DMSP)-consuming bacteria (DCB) were investigated in the East China Sea and the Yellow Sea in summer 2013.1. DCB abundance and the correlation between DCB abundance and temperature, salinity or chlorophyll a (Chi a) concentration(1) Higher Chi a concentrations were mainly distributed in the coastal waters of Jiangsu and Zhejiang.Temperatures in the south were higher than those in the north, and the temperatures inshore were lower than those offshore. Salinities in the south were higher than those in the north, and the salinity in Yangtze river estuary were very low because of Changjiang Diluted Water. For the cross section C, temperatures reduced gradually from the surface water to the bottom water, the salinity increases with the increase of the depth, and higher Chi a concentrations mostly appeared in the depths of 10-30 m.(2) Horizontal distribution:DCB abundance in the surface waters ranged from 2.3×102 cells ml/1 to 2.30×104 cells ml/1, with an average of 1.41×105 cells mL-1. The minimum and maximum values occurred at Station F07 and MCl, respectively. Higher DCB abundance areas were mainly located in the South Yellow Sea, west of Jeju Island and coastal waters near Zhejiang Province. Lower value areas mainly appeared in coastal waters of the South Yellow Sea near Shandong and Jiangsu. Vertical distribution:DCB abundances of C section ranged from 2.30×102 cells mL-1 to 2.30×104 cells mL-1. The maximum DCB abundance appeared at 10 m of Station C01 offshore, while the minimum DCB abundance appeared at 30 m of C05 station offshore. DCB abundance showed the general pattern that DCB abundances nearshore were higher than those offshore. Diurnal variation:In Station MT1, DCB abundance gradually increased from 11:00 am. to 23:00 pm., and higher DCB occurred at night and lower DCB occurred during the day.(3) The correlation between the DCB abundance and temperature, salinity and/or Chl a concentration are all not significant (P>0.05). DCB abundances were positively correlated with DMS, DMSPd concentrations (P< 0.05), respectively, and DCB abundances were significantly positively correlated with DMSPP and DMSPt concentrations (P< 0.01), respectively.2. Investigation of the diversity of DCB(1) We used molecular biology techniques and identified 48 stains of DCB using DMSP as the sole carbon source. DCB is dominated with Proteobacteria both in abundance and species richness. The bacteria isolated mainly included Agrobacterium (2), Pseudomonas (5), Alteromonas (10), Pseudoalteromonas (3), Bacillus (14), Ruegeria (1), Klebsiella (2), Paenibacillus (1), Staphylococcus (2), Halomonas (1), Alcanivorax (1), Enterobacter (1), Erythrobacter (1), Arthrobacter (1), Rhodobacteraceae (1), Sagittula (1), Phaeobacter (1) and Glacial ice bacterium (1). Among them,23 strains of bacteria belonged to y-Proteobacteria,17 strains of bacteria belonged to Firmicutes,6 strains of bacteria belonged to a-Proteobacteria and 1 strains bacteria belonged to Arthrobacter.(3) Glacial ice bacterium G500K-19, Agrobacterium tumefaciens and Alteromonas sp. S129 are the most widely distributed DCB, followed by Alteromonas macleodii ATCC 27126. The species diversity of DCB in the seawater of C section is very rich, containing 18 strains of bacteria and covering 8 genuses including Agrobacterium, Alcanivorax, Alteromonas, Bacillus, Glacial ice bacterium, Halomonas, Pseudomonas, Ruegeria et al.3. Investigation of the degradation characteristics of DCB(1) Alteromonas sp. S129 could grow using DMSP as the sole carbon source. Alteromonas sp. S129 grew rapidly in higher concentrations of DMSP, and more DMS was produced. The results of degradation kinetics of Alteromonas sp. S129 for DMSP showed that Km and Fmax were 479.4μM (SD= 349.5) and 84.30μM/d (SD= 26.27), respectively.(2) Alteromonas sp. S129 could grow when acrylic and/or glycine betaine was utilized as carbon source beside DMSP. The bacteria grew the best when glycine betaine was used as carbon source, followed by acrylic acid. Bacteria grow more rapidly under high concentrations of betaine and/or acrylic than at low concentrations. Alteromonas sp. S129 could not grow well when methylamine (MMA), dimethylamine (DMA) or dimethylsulfoxide (DMSO) was used as the sole carbon source. Therefore, Alteromonas sp. S129 could effectively use the carbon in the carbon chain rather than use methyl carbon.