Search

The Great Pacific Garbage Patch, a significant collection of plastic introduced by human activities, provides an ideal environment to study bacterial lifestyles on plastic substrates. We proposed that bacteria colonizing the floating plastic debris would develop strategies to deal with the ultraviolet‐exposed substrate, such as the production of antioxidant pigments. We observed a variety of pigmentation in 67 strains that were directly cultivated from plastic pieces sampled from the Garbage Patch. The genomic analysis of four representative strains, each distinct in taxonomy, revealed multiple pathways for carotenoid production. These pathways include those that produce less common carotenoids and a cluster of photosynthetic genes. This cluster appears to originate from a potentially new species of the Rhodobacteraceae family. This represents the first report of an aerobic anoxygenic photoheterotrophic bacterium from plastic biofilms. Spectral analysis showed that the bacteria actively produce carotenoids, such as beta‐carotene and beta‐cryptoxanthin, and bacteriochlorophyll a. Furthermore, we discovered that the genetic ability to synthesize carotenoids is more common in plastic biofilms than in the surrounding water communities. Our findings suggest that plastic biofilms could be an overlooked source of bacteria‐produced carotenoids, including rare forms. It also suggests that photoreactive molecules might play a crucial role in bacterial biofilm communities in surface water. [ABSTRACT FROM AUTHOR]

Four rod-shaped, non-motile, non-spore-forming, facultative anaerobic, Gram-stain-positive lactic acid bacteria, designated as EB0058 T , SCR0080, LD0937 T and SCR0063 T , were isolated from different corn and grass silage samples. The isolated strains were characterized using a polyphasic approach and EB0058 T and SCR0080 were identified as Lacticaseibacillus zeae by 16S rRNA gene sequence analysis. Based on whole-genome sequence-based characterization, EB0058 T and SCR0080 were separated into a distinct clade from Lacticaseibacillus zeae DSM 20178 T , together with CECT9104 and UD2202, whose genomic sequences are available from NCBI GenBank. The average nucleotide identity (ANI) values within the new subgroup are 99.9 % and the digital DNA-DNA hybridization (dDDH) values are 99.3-99.9 %, respectively. In contrast, comparison of the new subgroup with publicly available genomic sequences of L. zeae strains, including the type strain DSM 20178 T , revealed dDDH values of 70.2-72.5 % and ANI values of 96.2-96.6 %. Based on their chemotaxonomic, phenotypic and phylogenetic characteristics, EB0058 T and SCR0080 represent a new subspecies of L. zeae . The name Lacticaseibacillus zeae subsp. silagei subsp. nov. is proposed with the type strain EB0058 T (=DSM 116376 T =NCIMB 15474 T ). According to the results of 16S rRNA gene sequencing, LD0937 T and SCR0063 T are members of the Lacticaseibacillus group. The dDDH value between the isolates LD0937 T and SCR0063 T was 67.6 %, which is below the species threshold of 70 %, clearly showing that these two isolates belong to different species. For both strains, whole genome-sequencing revealed that the closest relatives within the Lacticaseibacillus group were Lacticaseibacillus huelsenbergensis DSM 11542 5 (dDDH 66.5 and 65.9 %) and Lacticaseibacillus casei DSM 20011 T (dDDH 64.1 and 64.9 %). Based on the genomic, chemotaxonomic and morphological data obtained in this study, two novel species, Lacticaseibacillus parahuelsenbergensis sp. nov. and Lacticaseibacillus styriensis sp. nov. are proposed and the type strains are LD0937 T (=DSM 116105 T =NCIMB 15471 T ) and SCR0063 T (=DSM 116297 T =NCIMB 15473 T ), respectively.

Novel, white-pigmented, Gram-negative bacterial strains (K-M0706 T , K-M0228, K-M0252, K-M0260) were isolated from clinical samples. With a similarity of up to 69.7 % to Serratia nevei S15 T and up to 63.8 % to Serratia marcescens ATCC 13880 T , as determined by digital DNA-DNA hybridization, the strains were assigned as novel species of the genus Serratia. The species can easily be differentiated from the red colored Serratia marcescens sensu stricto by its white phenotype. Discrimination between this strain and Serratia nevei is possible due to alpha-glucosidase activity and O/129-resistance, as shown for strain K-M0706 T . The major fatty acids were determined as myristate, palmitate, cis-9,10-methylenehexadecanoate, linoleate, and (all cis-9,10)-methyleneoctadecanoate. These phenotypical and genomic data support the assignment of a novel species within the genus Serratia, named S. sarumanii due to its pathogenicity and white phenotype, with strain K-M0706 T as the type strain., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier GmbH.. All rights reserved.)