Acinetobacter guillouiae, a lipolytic strain isolated from sludge capable of partially depolymerising polyethylene terephthalate: genomic, proteomic, and biochemical insights

Experimental, Genomic, and Structural Evidence Supporting Putative PET‐Hydrolases in Thermophilic Bacteria Isolated From Hot Springs in Cajamarca, Peru

ABSTRACT Polyethylene terephthalate (PET) waste represents a major environmental challenge due to limited recycling solutions. Thermophilic bacteria from geothermal environments harbor diverse enzymatic machinery adapted to extreme conditions, offering promising biocatalysts for plastic degradation; however, biological resources from Peru and other South American countries remain scarce. We characterized four bacterial strains isolated from two geothermal sites in Cajamarca, Peru, screened for PET hydrolysis at 50°C. Whole‐genome sequencing using hybrid assembly achieved near‐complete circular genomes. GTDB‐Tk classification identified three species: Neobacillus thermocopriae (strain 19A), Bacillus licheniformis (strains 16P and BI2), and Brevibacillus agri (strain BI8). Quantitative assays revealed that strain 16P achieved the highest mass loss (0.598%), followed by strain BI8 (0.449%). ATR‐FTIR analysis of the incubated sheets showed a significant reduction of the ester carbonyl index in strains 16P, 19A, and BI8 relative to both non‐incubated PET and an abiotic control, whereas strain BI2 did not differ from the controls, indicating preferential modification of ester bonds at the sheet surface. Genome mining and structure‐based homology searches identified multiple candidate enzymes similar to validated PETases and carboxylesterases, including PETase46‐like homologs in strains BI8 and 16P and a terephthalate‐active carboxylesterase homolog in strain 16P. Molecular docking supported the conservation of catalytic geometry and substrate‐binding sites in these candidates. This work represents one of the first systematic genomic and structural characterizations of putative PET‐hydrolases in Peruvian geothermal bacteria, expanding knowledge of extremophile diversity and advancing thermostable enzymes for sustainable plastic waste management.

High-cell-density fermentation of Komagataella phaffii enables the overproduction of a novel, broad-substrate endoglucanase, WcEG394 from Fuling (Wolfiporia cocos), for lignocellulose biorefining.

Recombinant WcEG394 efficiently hydrolyzed carboxymethyl cellulose, microcrystalline cellulose, and filter paper, and demonstrated broad substrate specificity toward xylans, pectin, chitin, agarose and agricultural residues such as corn cob and sugarcane bagasse.

Genomic and structural insights into the high-efficiency poly(3-hydroxybutyrate) biodegradation in Terrabacter sp. AAH1

By proposing a putative association between specific genomic features and macroscopic polymer degradation, this study suggests that Terrabacter sp.

Peptonella octanoica gen. nov., sp. nov., a new medium-chain carboxylate-producing bacterium, and the reclassification of Eubacterium pyruvativorans as Peptonella pyruvativorans comb. nov

Based on further phenotypic, genomic, and phylogenetic analysis, strain F2T represents a novel genus and species within the family Anaerovoracaceae with the proposed name Peptonella octanoica gen. sp.

Single-Vector Co-expression of petase and mhetase in E. coli Enhances PET Depolymerization Compared to Co-culture

Production and Characterization of Poly(3-hydroxybutyrate) by Thermophilic Geobacillus sp. Strain SL28 Isolated from a Natural Hot Spring

Polyhydroxyalkanoates (PHAs) are biodegradable microbial polyesters that may reduce dependence on petroleum-derived plastics, but broader use remains constrained by production costs and tightly controlled cultivation. Thermophilic microorganisms have attracted increasing attention as promising PHA producers because they can be cultivated at elevated temperatures, reducing contamination risks and operational costs. In this study, a thermophilic Geobacillus sp. strain SL28 isolated from a Vietnamese hot spring was evaluated for its PHA-producing capability. Temperature, initial pH, carbon and nitrogen sources, C/N ratio, and cultivation time were examined. Intracellular inclusions were assessed by Sudan Black B and Nile Blue A staining and transmission electron microscopy, whereas the recovered polymer was characterized by FE-SEM, Fourier-transform infrared spectroscopy (FTIR), gas chromatography–mass spectrometry (GC–MS), 1H- and 13C-nuclear magnetic resonance (NMR) spectroscopy, capillary viscometry, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and tensile testing. Under the optimized cultivation conditions identified by one-factor experimentation (50 °C, pH 7.0, sucrose, peptone, C/N 25:1, and 72 h), SL28 reached a dry cell weight of 2.215 ± 0.16 g/L and a PHA concentration of 1.383 ± 0.04 g/L, equivalent to 62.57 ± 2.82% of DCW. Structural characterization confirmed that the recovered polymer was poly(3-hydroxybutyrate) (PHB). The purified PHB also exhibited favorable thermal stability, a relatively high molecular weight, and satisfactory mechanical properties. These results demonstrate the potential of thermophilic Geobacillus sp. SL28 as a promising candidate for PHB production.