Biodegradation of recalcitrant compounds and phthalates by culturable bacteria isolated from Liometopum apiculatum microbiota

Biodegradation of phthalic acid and terephthalic acid by Comamonas testosteroni strains

Phthalic acid isomers are the monomers of phthalate molecules, also known as phthalic acid esters, widely employed in the plastics industry. This study aims to investigate the biodegradation of phthalic acid (PA) and terephthalic acid (TPA) by five industry-borne Comamonas testosteroni strains: 3APTOL, 3ABBK, 2B, 3A1, and C8. To assess the ability of C. testosteroni strains to biodegrade phthalic acid isomers in fermentation media, an analytical method was employed, consisting of high-performance liquid chromatography (HPLC) analyses. Subsequently, molecular screening of the genomic and plasmid DNA was conducted to identify the degradative genes responsible for the breakdown of these chemicals. The genes of interest, including ophA2, tphA2, tphA3, pmdA, and pmdB, were screened by real-time PCR. The five C. testosteroni strains effectively degraded 100% of 100 mg/L PA (p = 0.033) and TPA (p = 0.0114). Molecular analyses indicated that all C. testosteroni strains contained the pertinent genes at different levels within their genomes and plasmids, as reflected in the threshold cycle (Ct) values. Additionally, DNA temperature of melting (Tm) analyses uncovered minor differences between groups of genes in genomic and plasmid DNA. C. testosteroni strains could be excellent candidates for the removal of phthalic acid isomers from environmental systems.

Sex-specific bacterial microbiome variation in octopus vulgaris skin

Growing knowledge of the host-microbiota of vertebrates has shown the prevalence of sex-specific differences in the microbiome. However, there are virtually no studies assessing sex-associated variation in the microbiome of cephalopods. Here we assess sex-specific variation in the common octopus (Octopus vulgaris) skin microbiome using amplicon sequencing targeting the V4 hypervariable region of prokaryote 16S rRNA genes. Skin and mantle-associated mucus was collected from wild adult individuals of common Octopus (Octopus vulgaris) (9 males and 7 females of similar size). There were no significant differences in the alpha diversity of microbial communities associated with skin or mantle mucosa between sexes. However, our results clearly indicate that adult octopus males and females have a distinct microbial community composition in both skin and mantle associated mucus communities, with female microbiome being dominated by Firmicutes (48.1%), while that of males contained a majority of Proteobacteria (60.5%), with Firmicutes representing only 3.30%, not finding significant differentiation in the microbial communities between the tissues explored. The dominance of different taxa in the skin of O. vulgaris females and males (e.g., Mycoplasmatales and Lactococcus in females and Rhizobiales and Rhodobacteriales in males) suggests a sex-specific symbiosis in which those microbes benefit from easy access to distinct substrates present in female and male skin, respectively. Given the lack of differences in size between specimens of both sexes in this study, we hypothesize differences in hormone profile, as well as behavioral or ecological differences between sexes in the wild, as the main drivers of microbiome differentiation between sexes. Most knowledge of cephalopod microbiota is limited to the digestive tract and the reproductive system. However, cephalopod skin is an organ with a plethora of functions. This is a first attempt to characterize cephalopod skin microbiota and determine sex influence on it.

Application of compost assisted by Fe3O4 nanoparticles in di (2-ethylhexyl) phthalate-contaminated soil remediation: Biostimulation strategy, Soil responses, and RSM/CCD Optimization

Globally, contamination of agricultural soils by phthalate esters (PAEs) caused by direct consumption of plastic mulch films has been confirmed. The most widely used plasticizer is di (2-ethylhexyl) phthalate (DEHP), which is a more recalcitrant endocrine-disrupting chemical (EDC). Because of its low solubility and hydrophobicity, it remains in the soil longer, causes bioaccumulation in agricultural products, and has negative repercussions for food safety. In this study, the performance of kitchen organic waste compost assisted by Fe3O4 nanoparticles in DEHP removal efficiency (%) and soil C:N ratio (two responses) was optimized using Response Surface Methodology (RSM) based on Central Composite Design (CCD) in Design-Expert software (11.0.3.0). Under optimum conditions, a DEHP concentration of 10 mg·kg-1 (dw soil), a retention time of 35 days, an NPs dose of 0.99 g·kg-1 (media), a removal efficiency of 91.6 %, and a soil C:N ratio of 10.5 with a desirability of 0.963 were determined. A quadratic model (P-value <0.0001, adjusted R2 = 0.974 (Y1), 0.943 (Y2)) was used to predict the variables and their interactions. The agricultural soil responses in the treatments amended by compost and Fe3O4 NPs (SCN) showed a significant increase in SOM, TC, TN, AP, K, and Fe nutrients when compared to the control (P < 0.05). After 35 days, in the SC1N3 treatment (DEHP concentration = 10 mg·kg-1, NPs dose =1.2 g·kg-1), with higher DEHP removal efficiency (89.57 %), the C:N:P ratio was equal to 100: 9.75:0.69, and the total microbial colony count was 3.6 × 109 CFU/ml at pH 7.45. The study found that compost nutrients and Fe-based nanoparticle micronutrients can enhance DEHP degradation by stimulating the soil's native microflora. As a result, the synergistic potential of compost and Fe3O4 nanoparticles can be considered a promising, cost-effective, and agri-environmentally friendly approach in the "assisted bioremediation" strategy of DEHP-contaminated soils.

Arthropod-Microbiota Integration: Its Importance for Ecosystem Conservation

Recent reports indicate that the health of our planet is getting worse and that genuine transformative changes are pressing. So far, efforts to ameliorate Earth's ecosystem crises have been insufficient, as these often depart from current knowledge of the underlying ecological processes. Nowadays, biodiversity loss and the alterations in biogeochemical cycles are reaching thresholds that put the survival of our species at risk. Biological interactions are fundamental for achieving biological conservation and restoration of ecological processes, especially those that contribute to nutrient cycles. Microorganism are recognized as key players in ecological interactions and nutrient cycling, both free-living and in symbiotic associations with multicellular organisms. This latter assemblage work as a functional ecological unit called "holobiont." Here, we review the emergent ecosystem properties derived from holobionts, with special emphasis on detritivorous terrestrial arthropods and their symbiotic microorganisms. We revisit their relevance in the cycling of recalcitrant organic compounds (e.g., lignin and cellulose). Finally, based on the interconnection between biodiversity and nutrient cycling, we propose that a multicellular organism and its associates constitute an Ecosystem Holobiont (EH). This EH is the functional unit characterized by carrying out key ecosystem processes. We emphasize that in order to meet the challenge to restore the health of our planet it is critical to reduce anthropic pressures that may threaten not only individual entities (known as "bionts") but also the stability of the associations that give rise to EH and their ecological functions.

Biodegradation of diisononyl phthalate by a consortium of saline soil bacteria: optimisation and kinetic characterisation

Diisononyl phthalate (DINP) is one of plasticisers most employed in the production of plastic materials and belongs to the most important environmental contaminants. In this work, a consortium of saline soil bacterial (SSB) capable of degrading DINP is presented. The genera of SSB-consortium were Serratia sp., Methylobacillus sp., Achromobacter sp., Pseudomonas sp., Stenotrophomonas sp., Methyloversatilis sp., Delftia sp. and Brevundimonas sp. Response surface methodology (RSM) study was employed to optimise and evaluate the culture conditions to improve the biodegradation of DINP. The optimal conditions were a pH 7.0, 31 °C and an initial DINP concentration of 500 mg L^-1, resulting in almost complete biodegradation (99%) in 168 h. DINP degradation followed a first-order kinetic model, and the half-life was 12.76 h. During the biodegradation of DINP, 4-derived compounds were identified: monoisononyl phthalate, methyl nonyl phthalate, iso-nonanol and dimethyl phthalate. The metabolite profiling indicated that DINP was degraded through simultaneous pathways of de-esterification and β-oxidation. Results suggest that the SSB-consortium could be useful for efficient biodegradation of the DINP-contaminated environments. KEY POINTS: • DINP degradation is mediated by de-esterification and β-oxidation processes. • Temperature and the concentration of the substrate are key factors for DINP biodegradation • The SSB-consortium has the ability to biodegrade 99% of DINP (500 mg L^-1).