Faecal contamination determines bacterial assemblages over natural environmental parameters within intermittently opened and closed lagoons (ICOLLs) during high rainfall.

Intermittently closed and opened lakes and lagoons (ICOLLs) provide important ecosystem services, including food provision and nutrient cycling. These ecosystems generally experience low watershed outflow, resulting in substantial fluctuations in physicochemical parameters that are often compounded by anthropogenic contamination, however, how this impacts the patterns in microbiology within these environments remains uncharacterised. Therefore, we aimed to determine how seasonal heterogeneity in the physicochemical parameters, in comparison to faecal contamination, alter the dynamics of bacterial communities inhabiting ICOLLs on the eastern Australian coast.

Widespread production of plant growth-promoting hormones among marine bacteria and their impacts on the growth of a marine diatom.

Background: Reciprocal exchanges of metabolites between phytoplankton and bacteria influence the fitness of these microorganisms which ultimately shapes the productivity of marine ecosystems. Recent evidence suggests that plant growth-promoting hormones may be key metabolites within mutualistic phytoplankton-bacteria partnerships, but very little is known about the diversity of plant growth-promoting hormones produced by marine bacteria and their specific effects on phytoplankton growth. Here, we aimed to investigate the capacity of marine bacteria to produce 7 plant growth-promoting hormones and the effects of these hormones on Actinocyclus sp.

Coral endosymbiont growth is enhanced by metabolic interactions with bacteria.

Bacteria are key contributors to microalgae resource acquisition, competitive performance, and functional diversity, but their potential metabolic interactions with coral microalgal endosymbionts (Symbiodiniaceae) have been largely overlooked. Here, we show that altering the bacterial composition of two widespread Symbiodiniaceae species, during their free-living stage, results in a significant shift in their cellular metabolism. Indeed, the abundance of monosaccharides and the key phytohormone indole-3-acetic acid (IAA) were correlated with the presence of specific bacteria, including members of the Labrenzia (Roseibium) and Marinobacter genera.

Temporal variability in the growth-enhancing effects of different bacteria within the microbiome of the diatom sp.

Reciprocal metabolite exchanges between diatoms and bacteria can enhance the growth of both partners and therefore fundamentally influence aquatic ecosystem productivity. Here, we examined the growth-promoting capabilities of 15 different bacterial isolates from the bacterial community associated with the marine diatom sp. and investigated the magnitude and timing of their effect on the growth of this diatom.

Diatom Biogeography, Temporal Dynamics, and Links to Bacterioplankton across Seven Oceanographic Time-Series Sites Spanning the Australian Continent.

Diatom communities significantly influence ocean primary productivity and carbon cycling, but their spatial and temporal dynamics are highly heterogeneous and are governed by a complex diverse suite of abiotic and biotic factors. We examined the seasonal and biogeographical dynamics of diatom communities in Australian coastal waters using amplicon sequencing data (18S-16S rRNA gene) derived from a network of oceanographic time-series spanning the Australian continent. We demonstrate that diatom community composition in this region displays significant biogeography, with each site harbouring distinct community structures.