Bacterial ability to deploy the type VI secretion system (T6SS) against rivals requires prolonged cell-cell interactions. Such interactions are facilitated on solid surfaces but are assumed to be absent in liquid, leading to the conventional dismissal of T6SS-mediated competition in liquid environments. Here, we find that Aeromonas jandaei employs its T6SS to eliminate diverse bacterial competitors in liquid media. Using a workflow that monitors interbacterial competition via prey luminescence, we demonstrate that auto-aggregation and co-aggregation, facilitated by distinct adhesins, enable kin and non-kin recognition and intoxication in a T6SS-dependent manner. Furthermore, we show that another marine bacterium, Vibrio coralliilyticus , employs T6SS to intoxicate rivals in liquid media. Collectively, our results indicate that T6SS-mediated competition in liquid is more common in marine bacteria than previously anticipated, and can be facilitated by diverse molecular mechanisms that govern cell aggregation. ### Competing Interest Statement The authors have declared no competing interest. Israel Science Foundation, https://ror.org/04sazxf24, 1362/21, 2174/22 Swiss National Science Foundation, 51NF40_180541

One of the worst players in the NHL gets voted into the All-Star Game.

Protein structure is conserved beyond sequence, making multiple structural alignment (MSTA) essential for analyzing distantly related proteins. Computational prediction methods have vastly extended ou...

Extracellular contractile injection systems (eCISs) are bacteriophage tail-derived toxin delivery complexes that are present in many prokaryotes. Here, the authors present an analysis of eCIS tail fib...

EMBL and its community are deeply saddened by the death of Peer Bork, the organisation’s Interim Director General.

Yersinia pseudotuberculosis senses fungal tyrosol signalling through EnvZ–OmpR which triggers T6SS activation and antifungal effector release to reduce fungal competitors in the mouse gut.

Whole-genome and transcriptome analysis of 1,364 cases of breast cancer from South Korea broadens our understanding of breast cancer biology and reveals genomic features that connect tumour ...

Phages often degrade the genome of their bacterial host to individual nucleotides and use these nucleotides to build their own genome. In this study, we describe a bacterial defense system that direct...