Draft genome sequences of six bacteria isolated from polylactic acid samples from the Mediterranean Sea.

Here, we report the draft genome sequences of six marine strains isolated from plastic samples incubated in the Mediterranean Sea. Genomic analyses place these strains within the Alkalihalobacillus, Bacillus, Halomonas, and Marinobacter genera. Examining the genomes of these non-typical environmental bacteria increases our comprehension of microorganism biology and their potential uses.

Paenarthrobacter sp. GOM3 Is a Novel Marine Species With Monoaromatic Degradation Relevance.

Paenarthrobacter sp. GOM3, which is a strain that represents a new species-specific context within the genus Paenarthrobacter, is clearly a branched member independent of any group described thus far. This strain was recovered from marine sediments in the Gulf of Mexico, and despite being isolated from a consortium capable of growing with phenanthrene as a sole carbon source, this strain could not grow successfully in the presence of this substrate alone. We hypothesized that the GOM3 strain could participate in the assimilation of intermediate metabolites for the degradation of aromatic compounds. To date, there are no experimental reports of Paenarthrobacter species that degrade polycyclic aromatic hydrocarbons (PAHs) or their intermediate metabolites. In this work, we report genomic and experimental evidence of metabolic benzoate, gentisate, and protocatechuate degradation by Paenarthrobacter sp. GOM3. Gentisate was the preferred substrate with the highest volumetric consumption rate, and genomic analysis revealed that this strain possesses multiple gene copies for the specific transport of gentisate. Furthermore, upon analyzing the GOM3 genome, we found five different dioxygenases involved in the activation of aromatic compounds, suggesting its potential for complete remediation of PAH-contaminated sites in combination with strains capable of assimilating the upper PAH degradation pathway. Additionally, this strain was characterized experimentally for its pathogenic potential and in silico for its antimicrobial resistance. An overview of the potential ecological role of this strain in the context of other members of this taxonomic clade is also reported.

Inactivation of an intracellular poly-3-hydroxybutyrate depolymerase of Azotobacter vinelandii allows to obtain a polymer of uniform high molecular mass.

A novel poly-3-hydroxybutyrate depolymerase was identified in Azotobacter vinelandii. This enzyme, now designated PhbZ1, is associated to the poly-3-hydroxybutyrate (PHB) granules and when expressed in Escherichia coli, it showed in vitro PHB depolymerizing activity on native or artificial PHB granules, but not on crystalline PHB. Native PHB (nPHB) granules isolated from a PhbZ1 mutant had a diminished endogenous in vitro hydrolysis of the polyester, when compared to the granules of the wild-type strain. This in vitro degradation was also tested in the presence of free coenzyme A. Thiolytic degradation of the polymer was observed in the nPHB granules of the wild type, resulting in the formation of 3-hydroxybutyryl-CoA, but was absent in the granules of the mutant. It was previously reported that cultures of A. vinelandii OP grown in a bioreactor showed a decrease in the weight average molecular weight (Mw) of the PHB after 20 h of culture, with an increase in the fraction of polymers of lower molecular weight. This decrease was correlated with an increase in the PHB depolymerase activity during the culture. Here, we show that in the phbZ1 mutant, neither the decrease in the Mw nor the appearance of a low molecular weight polymers occurred. In addition, a higher PHB accumulation was observed in the cultures of the phbZ1 mutant. These results suggest that PhbZ1 has a role in the degradation of PHB in cultures in bioreactors and its inactivation allows the production of a polymer of a uniform high molecular weight.