Complete Genome Sequence of Kosakonia sp. Strain CCTCC M2018092, a Fucose-Rich Exopolysaccharide Producer

Enhancement of the phytoremediation performance in heavy metal-contaminated soil using a multifunctional EPS-producing bacterium Kosakonia sp. W18

The use of exopolysaccharide (EPS)-producing bacteria for the phytoremediation of heavy metal-contaminated soil is emerging as a promising approach. This study explores the potential of Kosakonia sp. W18, an EPS-producing bacterium isolated from Suaeda japonica habitat, in the phytoremediation of heavy metal-contaminated soils. Strain W18 exhibited the highest tolerance to Pb (EC50 of 231.1 mg L-1), Cu, and Cr (EC50 of 24.9 and 26.7 mg L-1), and displayed plant growth-promoting traits. The EPS extracted from W18 (107.3 mg L-1) showed 58% emulsification against chloroform, remarkable 2,2-Diphenyl-1-picrylhydrazyl (38%) and hydroxyl radical (83%) scavenging activities. Extracted EPS also exhibited a Pb-removal efficiency exceeding 79%, with an adsorption capacity for Pb of 499.2 ± 7.7 mg·g-EPS-1. In the contaminated soils with Pb (500 mg kg-1) and Cr (100 mg kg-1), W18 inoculation significantly enhanced pakchoi shoot length and biomass by 1.1-1.3 times after 20 days. The presence of pakchoi decreased bioavailable Pb and Cr concentrations in soil by 46%, which elevated to 76% for Pb and 72% for Cr post-inoculation with W18. Furthermore, W18 enhanced Pb uptake in pakchoi roots, increasing the bioconcentration factor by over 1.5 times and large macroaggregates (>2 mm) formation exceeded 75%. Overall, this study highlights Kosakonia sp. W18's multifunctional abilities to promote pakchoi growth and improve its effectiveness in phytoremediation of heavy metals in contaminated soils.

Exploring the potential of 1,8-cineole from cardamom oil against food-borne pathogens: Antibacterial mechanisms and its application in meat preservation

Food-borne pathogenic bacteria are a major public health concern globally. Traditional control methods using antibiotics have limitations, leading to the exploration of alternative strategies. Essential oils such as cardamom possess antimicrobial properties and have shown efficacy against food-borne pathogenic bacteria. The utilization of essential oils and their bioactive constituents in food preservation is a viable strategy to prolong the shelf-life of food products while ensuring their quality and safety. To the best of our knowledge, there are no studies that have utilized 1,8-cineole (the main active constituent of cardamom essential oil) as a preservative in meat, so this study might be the first to utilize 1,8-cineole as an antibacterial agent in meat preservation. The application of 1,8-cineole had a significant suppressive impact on the growth rate of Listeria monocytogenes, Staphylococcus aureus, Escherichia coli, and Salmonella Typhimurium in meat samples stored for 7 days at 4 °C. Additionally, the surface color of the meat samples was not negatively impacted by the application of 1,8-cineole. The minimum inhibitory concentration was 12.5-25 mg/ml, and the minimum bactericidal concentration was 25-50.0 mg/ml. The bacterial cell membrane may be the target of cardamom, causing leakage of intracellular proteins, ATP, and DNA. The obtained data in this study may pave a new avenue for using 1,8-cineole as a new perspective for dealing with this problem of food-borne pathogens and food preservation, such as meat.

Physico-Chemical and Metagenomic Profile Analyses of Animal Manures Routinely Used as Inocula in Anaerobic Digestion for Biogas Production

Anaerobic digestion (AD) of organic waste is considered a sustainable solution to energy shortage and waste management challenges. The process is facilitated by complex communities of micro-organisms, yet most wastes do not have these and thus need microbial inoculation using animal manures to initiate the process. However, the degradation efficiency and methane yield achieved in using different inocula vary due to their different microbial diversities. This study used metagenomics tools to compare the autochthonous microbial composition of cow, pig, chicken, and horse manures commonly used for biogas production. Cows exhibited the highest carbon utilisation (>30%) and showed a carbon to nitrogen ratio (C/N) favourable for microbial growth. Pigs showed the least nitrogen utilisation (<3%) which explains their low C/N whilst horses showed the highest nitrogen utilisation (>40%), which explains its high C/N above the optimal range of 20−30 for efficient AD. Manures from animals with similar gastrointestinal tract (GIT) physiologies were observed to largely harbour similar microbial communities. Conversely, some samples from animals with different GITs also shared common microbial communities plausibly because of similar diets and rearing conditions. Insights from this study will lay a foundation upon which in-depth studies of AD metabolic pathways and strategies to boost methane production through efficient catalysis can be derived.

Proposal for Unification of the Genus Metakosakonia and the Genus Phytobacter to a Single Genus Phytobacter and Reclassification of Metakosakonia massiliensis as Phytobacter massiliensis comb. nov

The genus Metakosakonia, as the closest phylogenetic neighbor of the genus Kosakonia within the family Enterobacteriaceae, when proposed in 2017, consisted of M. massiliensis JC163^T and Metakosakonia spp. strains CAV1151 and GT-16. The strain CAV1151 was later classified into a novel species Phytobacter ursingii. Here, we show that the strain GT-16 shares a digital DNA-DNA hybridization (DDH) similarity of 91.0% with P. diazotrophicus DSM 17806 ^T and thus also belongs to P. diazotrophicus. M. massiliensis and the strains within the genus Phytobacter formed a monophyletic cluster on a phylogenomic tree based on the core proteins of the family Enterobacteriaceae and on a phylogenetic tree based on the 16S rRNA genes. M. massiliensis and the genus Phytobacter share average amino acid identities of 86.80‒87.41% above the threshold (86%) for genus delimitation within the family Enterobacteriaceae. Moreover, they share conserved signature indels in the intracellular growth protein IgaA and the outer membrane assembly protein AsmA. Therefore, we propose to unite the genus Metakosakonia and the genus Phytobacter to a single genus. Because the genus Phytobacter was validly published earlier in 2017 than the genus Metakosakonia in 2017, the genus name Phytobacter has priority over Metakosakonia. We propose to unite the two genera under the name Phytobacter with the type species P. diazotrophicus and reclassify M. massiliensis as P. massiliensis comb. nov. In addition, the analyses of genome relatedness and phylogenomic relationship identified one potential novel species within the genus Phytobacter and three potential novel species within the genus Kosakonia.