N-alkane shape distinctive microbial patterns in Kuroshio Extension.

Marine microorganisms are primary drivers of the elemental cycling. The interaction between heterotrophic prokaryotes and biomarker (n-alkane) in Kuroshio Extension (KE) remains unclear. Here, we categorize KE into three characteristic areas based on ocean temperatures and nutrient conditions: Cold Water Area (CWA), Mixed Area (MA), and Warm Water Area (WWA). A total of 49 samples were collected during two-year voyage to identify the source of n-alkane and associated degrading microorganisms. Total n-alkane concentrations (Σn-Alk) in surface water (SW) spanned from 1,308 ng L to 1,890 ng L, it was significantly higher (Tukey-Kramer test, p < 0.05) in MA than CWA and WWA. The Σn-Alk in surface sediments (SS) gradually increased from north to south, ranging from 5,982 ng g to 37,857 ng g. Bacteria and algae were the primary sources of n-alkane in both SW and SS. Proteobacteria was the most widely distributed among three areas. The presence of Rhodobacteraceae with alkB was the primary reason affecting n-alkane concentrations in SW. The Gammaproteobacteria with alkB and alkR chiefly affected n-alkane concentrations in SS. In summary, n-alkane s serve as an energy source for particular microorganisms, shaping the unique oceanographic patterns.