Microscale Nutrient Patches in Planktonic Habitats Shown by Chemotactic Bacteria

TLDR

Microbial communities may rely on transient nutrient micropatches, but it is unclear whether these patches persist long enough to influence growth and competition or what their sources are. The study examined the swimming behavior of chemotactic bacteria in seawater samples to determine the persistence and origins of such nutrient patches. Bacterial clusters formed around protozoan lysis and excretion, creating millimeter‑scale nutrient patches that lasted about ten minutes and allowed most bacteria to encounter nutrients, showing that chemotaxis is advantageous in patches above a critical size.

Abstract

Are nutrients available to microbial communities in micropatches long enough to influence growth and competition? And what are the sources of such patches? To answer these questions, the swimming behavior of chemotactic bacteria in seawater samples was examined. Clusters of bacteria formed in conjunction with cell lysis and excretion by protozoa. These point sources of nutrients spread into spherical patches a few millimeters in diameter and sustained swarms of bacteria for about 10 minutes. Within that time, a large proportion of the nutrients was encountered by bacteria, chemotactic and nonchemotactic alike. Chemotaxis is advantageous for bacteria using patches over a certain size.