Associated bacterial microbiome responds opportunistic once algal host Scenedesmus vacuolatus is attacked by endoparasite Amoeboaphelidium protococcarum

Abstract

The interactions of microalgae and their associated microbiomes have come to the fore of applied phycological research in recent years. However, the functional mechanisms of microalgal interactions remain largely unknown. Here, we examine functional protein patterns of the microalgae Scenedesmus vacuolatus and its associated bacterial community during algal infection by the endoparasite Amoeboaphelidium protococcarum. We performed metaproteomics analyses of non-infected (NI) and aphelid-infected (AI) S.vacuolatus cultures to investigate underlying functional and physiological changes under infectious conditions. We observed an increase in bacterial protein abundance as well as a severe shift of bacterial functional patterns throughout aphelid-infection in comparison to NI treatment. Most of the bacterial proteins (about 55%) upregulated in AI were linked to metabolism and transport of amino acids, lipids, coenzymes, nucleotides and carbohydrates and to energy production. Several proteins associated with pathogenic bacterial-plant interactions showed higher protein abundance levels in AI treatment. These functional shifts indicate that associated bacteria involved in commensalistic or mutualistic interactions in NI switch to opportunistic lifestyles and facilitate pathogenic or saprotrophic traits in AI treatment. In summary, the native bacterial microbiome adapted its metabolism to algal host die off and is able to metabolize nutrients from injured cells or decompose dead cellular material.

Unravelling microalgal-bacterial interactions in aquatic ecosystems through 16S rRNA gene-based co-occurrence networks

“…iron 4,5 ) and growth promoting hormones 6 by bacteria in exchange for organic carbon from the algae. Apart from many beneficial interactions, some bacteria can have negative influences on algae by being algicidal and opportunistic pathogens [7][8][9] . A recent study on the bloom-forming Phaeocystis algae revealed that its microbiomes can take both symbiotic and opportunistic modes 10 .…”

Impact of photobioreactor design on microalgae-bacteria communities grown on wastewater: Differences between thin-layer cascade and thin-layer raceway ponds

“…1). CV cultivation in TLC showed the presence at high abundance of Vannella (9-11%), an ameboid protist, followed by Amoeboaphelidium protococcarum (6-8%), an algal parassitoid (Hoeger et al, 2022), and as expected Chlorella (5-8%). On the other hand, CV cultures in RW showed a predominant contamination of the ciliate Sterkiella that feeds on microalgae (33-39%) which, together with the absence of Chlorella, might identify a "failed culture" respect to the inoculum introduced.…”

Microbial Diversity and Community Structure of Wastewater-Driven Microalgal Biofilms

“…These beneficial interrelations allow higher efficiencies in the removal of organic matter and nutrients in wastewater treatment than standalone microalgal or bacterial systems [24,28,61]. However, apart from many useful interactions, some heterotrophs/saprophytes/parasites can have negative influences on the periphytic community by being algicidal and opportunistic pathogens [13,63].…”