Genome of Alcanivorax sp. 24 : a hydrocarbon degrading bacterium isolated from marine plastic debris

Alcanivorax is an important member of the hydrocarbonoclastic group known for using alkanes and other related compound as their preferred carbon source. Here we report the genomic characteristics of Alcanivorax sp. 24 isolated from plastic marine debris. Its 4,765,873 bp genome, containing 4239 coding sequences, revealed the presence of all genomic features involved in alkane degradation (i.e. two cytochrome P450, three alkane monooxygenases AlkB and two enzymes involved in the degradation of long-chain alkanes AlmA) as well as other relevant enzymes that may play a role in the biodegradation of other polymers such as polyhydroxybutyrate. The genome features and phylogenetic context of these genes provide interesting insight into the lifestyle versatility of Alcanivorax sp. living in the plastisphere of marine plastic debris

Genome of Alcanivorax sp. 24: A hydrocarbon degrading bacterium isolated from marine plastic debris.

[eng] Alcanivorax is an important member of the hydrocarbonoclastic group known for using alkanes and other related compound as their preferred carbon source. Here we report the genomic characteristics of Alcanivorax sp. 24 isolated from plastic marine debris. Its 4,765,873 bp genome, containing 4239 coding sequences, revealed the presence of all genomic features involved in alkane degradation (i.e. two cytochrome P450, three alkane monooxygenases AlkB and two enzymes involved in the degradation of long-chain alkanes AlmA) as well as other relevant enzymes that may play a role in the biodegradation of other polymers such as polyhydroxybutyrate. The genome features and phylogenetic context of these genes provide interesting insight into the lifestyle versatility of Alcanivorax sp. living in the plastisphere of marine plastic debris

Marine plastic debris: a new surface for microbial colonization.

[eng] Plastics become rapidly colonized by microbes when released into marine environments. This microbial community the Plastisphere has recently sparked a multitude of scientific inquiries and generated a breadth of knowledge, which we bring together in this review. Besides providing a better understanding of community composition and biofilm development in marine ecosystems, we critically discuss current research on plastic biodegradation and the identification of potentially pathogenic "hitchhikers" in the Plastisphere. The Plastisphere is at the interface between the plastic and its surrounding milieu, and thus drives every interaction that this synthetic material has with its environment, from ecotoxicity and new links in marine food webs to the fate of the plastics in the water column. We conclude that research so far has not shown Plastisphere communities to starkly differ from microbial communities on other inert surfaces, which is particularly true for mature biofilm assemblages. Furthermore, despite progress that has been made in this field, we recognize that it is time to take research on plastic-Plastisphere-environment interactions a step further by identifying present gaps in our knowledge and offering our perspective on key aspects to be addressed by future studies: (I) better physical characterization of marine biofilms, (II) inclusion of relevant controls, (III) study of different successional stages, (IV) use of environmentally relevant concentrations of biofouled microplastics, and (V) prioritization of gaining a mechanistic and functional understanding of Plastisphere communities

Beyond oil degradation: enzymatic potential of Alcanivorax to degrade natural and synthetic polyesters.

[eng] Pristine marine environments are highly oligotrophic ecosystems populated by well-established specialized microbial communities. Nevertheless, during oil spills, low-abundant hydrocarbonoclastic bacteria bloom and rapidly prevail over the marine microbiota. The genus Alcanivorax is one of the most abundant and well-studied organisms for oil degradation. While highly successful under polluted conditions due to its specialized oil-degrading metabolism, it is unknown how they persist in these environments during pristine conditions. Here, we show that part of the Alcanivorax genus, as well as oils, has an enormous potential for biodegrading aliphatic polyesters thanks to a unique and abundantly secreted alpha/beta hydrolase. The heterologous overexpression of this esterase proved a remarkable ability to hydrolyse both natural and synthetic polyesters. Our findings contribute to (i) better understand the ecology of Alcanivorax in its natural environment, where natural polyesters such as polyhydroxyalkanoates (PHA) are produced by a large fraction of the community and, hence, an accessible source of carbon and energy used by the organism in order to persist, (ii) highlight the potential of Alcanivorax to clear marine environments from polyester materials of anthropogenic origin as well as oils, and (iii) the discovery of a new versatile esterase with a high biotechnological potential

Pili allow dominant marine cyanobacteria to avoid sinking and evade predation.

[eng] How oligotrophic marine cyanobacteria position themselves in the water column is currently unknown. The current paradigm is that these organisms avoid sinking due to their reduced size and passive drift within currents. Here, we show that one in four picocyanobacteria encode a type IV pilus which allows these organisms to increase drag and remain suspended at optimal positions in the water column, as well as evade predation by grazers. The evolution of this sophisticated floatation mechanism in these purely planktonic streamlined microorganisms has important implications for our current understanding of microbial distribution in the oceans and predator-prey interactions which ultimately will need incorporating into future models of marine carbon flux dynamics