High-temperature stress induces bacteria-specific adverse and reversible effects on Ulva (Chlorophyta) growth and its chemosphere in a reductionist model system

Abstract

Axenic cultures of the green seaweed Ulva mutabilis were inoculated with bacteria providing essential algal growth and morphogenesis-promoting factors (AGMPFs) and were exposed to temperature shifts from 18 °C to 30 °C. The temperature-dependent effect of bacteria on longitudinal algal growth and the molecular composition of the chemosphere in the algal culture medium was explored. The reductionist tripartite model system of U. mutabilis, Roseovarius sp. MS2, and Maribacter sp. MS6 was applied as a reference and has been changed by substituting Roseovarius with isolates that phenocopy this strain. Rathayibacter festucae IH2 and Roseovarius aestuarii G8 boosted growth at 18 °C but slowed it down at 30 °C. Additional inoculation of Roseovarius sp. MS2 mitigated these adverse bacterial effects partially. At 30 °C, the molecular profile of the chemosphere differed dramatically between all tested tripartite communities, indicating different traits of the same bacterium with changing temperatures. Functional examinations should, therefore, accompany microbiome analysis to detect changing traits with the same microbiome composition.

Algal growth and morphogenesis-promoting factors released by cold-adapted bacteria contribute to the resilience and morphogenesis of the seaweedUlva(Chlorophyta) in Antarctica (Potter Cove)

“…Microbiome analysis was accompanied by functional examinations to investigate growth and morphogenesis-promoting traits within the microbiome (Hmani et al 2023). For this, bacteria were isolated from the surface of the algal samples using sterile swabs.…”

“…However, these functions may be broadly distributed across various taxonomic groups (Burke et al 2011). In addition, functional characteristics within the same microbiome can also change in a changing environment (Hmani et al 2023). By employing mass spectrometry profiling and imaging techniques, specific metabolic markers have been introduced to visualize the distribution of bacteria (the producers of metabolic markers) on the surface of Ulva spp.…”

Unveiling the culturable and non‐culturable actinobacterial diversity in two macroalgae species from the northern Portuguese coast

“…Microorganisms able to flourish in association with macroalgae living in such distinctive and challenging ecological niches are expected to possess unique adaptive mechanisms and diversity. Recently, studies using Chlorophyta Ulva species have shown that the macroalgae‐associated bacterial community, including Actinomycetota, can have beneficial and adverse effects on host growth and development depending on environmental stress conditions (Ghaderiardakani et al, 2017; Hmani et al, 2023). In the single study harnessing exclusively the diversity and bioactive potential of the Actinomycetota culturable community associated with kelp from the northern Portuguese shore, a rich reservoir of taxonomically diverse strains producing antimicrobial and anticancer metabolites was uncovered (Girão et al, 2019).…”