International Microbiology最新文献

Purpose: This study optimizes keratinase production from chicken-feather waste by Pseudomonas aeruginosa PA1045 and Alcaligenes faecalis IHB B 6507, characterize and apply their hydrolysates for organic fertilizer application.

Methods: Keratinolytic activities of P. aeruginosa PA1045 and A. faecalis IHB B 6507 were assessed on chicken feather media. Factors optimized were temperature, pH, substrate concentration and inoculum size. Chicken-feather hydrolysate (CFH) was characterized via Scanning Electron Microscopy (SEM), Fourier-Transform Infrared Spectroscopy (FTIR), protein and amino acid profiling using Bradford method and High-Performance Liquid Chromatography (HPLC) respectively. Following the application of CFH on maize plant, nitrogen content, phytochemical screening, chlorophyll concentration and plant growth parameters were assessed.

Result: Keratinolytic activity from P. aeruginosa peaked (42.48 U/mL) at day 5, while A. faecalis was maximum (40.88 U/mL) at day 7. Optimal keratinase production conditions by P. aeruginosa and A. faecalis were temperature 35 °C, pH 8.0, 1.5% substrate concentration and inoculum size of 2 mL and 3 mL, respectively. SEM analysis confirmed feather degradation and loss of structural integrity in hydrolysates (P. aeruginosa- PaH; A. faecalis- AfH) compared to the organized control, while FTIR analysis revealed distinct peaks indicating compositional differences. The PaH demonstrated higher protein (7.46 mg/100 g) and nitrogen (6.688 ± 1.08%) content. L-Threonine was the most dominant amino acid in both hydrolysates. Significantly, plants treated with PaH and AfH displayed enhanced growth compared to NPK fertilizer and water controls.

Conclusion: P. aeruginosa PA1045 and A. faecalis IHB B 6507 efficiently hydrolyzed chicken feathers under optimal conditions, yielding hydrolysates rich in essential amino acids, underscoring their multifaceted biotechnological applications in feather waste valorization and potential agricultural use.

Photography has revolutionized science by enabling the documentation and analysis of phenomena, including microbial cultures, where high-quality images are essential for research. However, certain inherent qualities of objects, such as the reflective surfaces of Petri dishes and the characteristics of fungal colonies, often compromise image quality. This highlights the need for accessible, low-cost solutions. Here, we present "Microbes, smile for the picture" (MSFP), a practical, portable, and affordable protocol using smartphones and a handmade photo studio equipped with a ring light, enabling standardized, high-quality images of microbial colonies for scientific and outreach purposes. The aim of this work is to describe the procedure for constructing the photograph studio and a protocol for obtaining high-quality photos. We believe that images captured using our studio and protocol can enhance scientific reproducibility and improve image quality for research, illustration, and science communication. Additionally, this protocol has the potential to be applied in other fields, generating high-quality images for educational and science popularization purposes.

We previously reported the mRNA levels of genes involved in the tricarboxylic acid cycle and the phosphoenolpyruvate-pyruvate-oxaloacetate node. Owing to the importance of the glycolytic pathway, massive mRNA sequencing of Streptomyces coelicolor grown in minimal medium with glucose as the sole carbon source was performed. The results revealed a large discrepancy between the mRNA levels of all the genes analysed; sco1947, encoding glyceraldehyde 3-phosphate dehydrogenase, had the highest relative levels with respect to those of the hrdB gene, with a decreasing trend over time in most cases. On the other hand, the genes encoding glucose kinase had the lowest expression levels. The existence of gene multiplicity in Streptomyces is well known, and S. coelicolor is no exception. Two, three, and even four paralogous genes were detected for some of the activities in this pathway, and not all of them were expressed under the growth conditions used. The results obtained showed the large differences in gene expression and in the activity of the enzymes involved in the glycolytic pathway, which may allow the design of strategies aimed at a better carbon flow in this microorganism.

Protease enzymes are widely used in industrial applications, often requiring resistance to alkaline and high-temperature conditions while maintaining activity in organic solvents. Discovering thermotolerant proteases from thermophilic organisms is crucial for such applications. This study aimed to identify a novel thermotolerant protease among 201 thermophilic strains isolated from hot springs in Aydın province. Geobacillus thermoleovorans HBB208 was identified as the most efficient protease producer, exhibiting a 3.1 (D/d) ratio on skim milk agar. The protease purified via ammonium sulfate precipitation, hydrophobic interaction, and ion-exchange chromatography, resulting in a 70.2-fold purification. SDS-PAGE and zymogram analyses confirmed the molecular weight of approximately 33.5 kDa and proteolytic activity. The enzyme showed optimal activity at pH 8.0 and 70 °C, and retained 50% activity after 30 min at 87.3 °C in the presence of 10 mM Ca²⁺, indicating remarkable thermostability. Kinetic analysis using casein as substrate yielded a K_m of 0.11 ± 0.01 mM, k_cat 27.4 ± 0.77, and 2.4 × 10⁵ k_cat/K_m. The enzyme was stable in the presence of various organic solvents and detergents and displayed broad substrate specificity. These findings suggest that HBB208pro metalloprotease enzyme is a promising candidate for biotechnological and industrial applications requiring extreme operational conditions.

This study investigated the potential of native arbuscular mycorrhizal fungi (AMF) isolated from organic cassava fields as a biofertilizer, assessing their effects on cassava growth both alone and in combination with plant growth-promoting bacteria (PGPB). AMF spores were isolated from the rhizospheric soil of organic cassava field soils in northeastern Thailand and grouped into two consortia based on spore size: A45 and A75. Molecular identification revealed that both consortia were dominated by the genera Claroideoglomus and Entrophospora, with Paraglomus additionally present in the A45 consortium. An outdoor pot experiment demonstrated that AMF inoculation significantly enhanced cassava growth compared to the uninoculated control, highlighting the potential of these locally adapted strains. Utilization of diverse AMF consortia showed better outcomes in cassava growth enhancement resulted from various abilities of AMF inside. However, the addition of the compatible PGPB strains (Pantoea dispersa and Serratia marcescens) did not further enhance plant growth. These findings emphasize the potential of locally adapted AMF consortia as effective biofertilizers for cassava and underscore the need for targeted evaluation of microbial interactions in sustainable agriculture.

Carotenoids are essential natural pigments, and ZISO plays a pivotal role in their biosynthesis. This study compares ZISO enzyme activity in Dunaliella salina and Dunaliella bardawil to evaluate their efficiency in synthesizing 9,9'-di-cis-ζ-carotene. Bacterial strains lacking ZISO (ΔDsZISO, ΔDbZISO) and ZDS (ΔDsZDS, ΔDbZDS) were constructed, and HPLC analysis revealed the accumulation of 9,9'-di-cis-ζ-carotene in ΔDbZDS but not in ΔDsZDS, suggesting that DbZISO exhibits higher activity. Molecular docking and kinetic simulations further indicate that DbZISO forms a more stable complex with 9,9',15-tri-cis-ζ-carotene, with a binding energy lower than that of DsZISO, where the affinity between DbZISO and the substrate is - 13.09 kcal/mol, and the affinity between DsZISO and the substrate is - 12.13 kcal/mol. These results demonstrate that DbZISO is more efficient than DsZISO in catalyzing the isomerization of carotenoid intermediates. This study provides mechanistic insights into ZISO-mediated carotenoid biosynthesis and establishes a foundation for metabolic engineering aimed at enhancing carotenoid production.

This study was conducted in response to the growing need for alternative microbial control strategies in the face of escalating antibiotic resistance, aiming to evaluate the antibacterial and antibiofilm potential of postbiotic components derived from Akkermansia muciniphila. Focusing on Enterococcus faecalis, a Gram-positive, biofilm-forming opportunistic pathogen, the effects of cell-free supernatant were analyzed in vitro on both planktonic growth and biofilm structures. The supernatant significantly suppressed planktonic proliferation, while biofilm assays revealed over 50% inhibition of biofilm formation and up to 40% disruption of preformed biofilms. These effects, confirmed via crystal violet staining, indicate that the supernatant possesses both preventive and curative antibiofilm properties. While the immunomodulatory and barrier-enhancing roles of A. muciniphila have been increasingly documented in the literature, this study provides direct experimental evidence of its antibiofilm efficacy, offering a novel perspective on its therapeutic scope. The findings suggest that postbiotics from A. muciniphila act not only through inhibition of bacterial growth but also by targeting biofilm-associated resistance mechanisms. Thus, A. muciniphila supernatant emerges as a promising and innovative candidate for next-generation antimicrobial and antibiofilm strategies, particularly for managing infections involving drug-resistant biofilm-forming pathogens.

This study establishes a scalable, GRAS-compliant bioprocess for hyaluronic acid (HA) production using Bacillus paralicheniformis PV154040.1, a novel strain isolated from local garden soil and identified via ribotyping. Through the systematic optimization of submerged fermentation conditions, M4 medium (5% glucose, 5% lactose, 1.5% tryptone, and 0.5% yeast extract) was identified as the most productive formulation. The optimal culture parameters were determined to be pH 6.5, a 72-hour incubation at 37 °C, and a 1.0 ml inoculum volume. A key finding was the significant enhancement in HA recovery using a cetyltrimethylammonium bromide (CTAB)-ethanol extraction method, which yielded 374.21 µg/ml, doubling the yield obtained with conventional ethanol precipitation (188.33 µg/ml; *p* ≤ 0.05). The identity of the biopolymer as HA was confirmed by Ultraviolet-Visible (UV/Vis) spectrophotometry, which showed characteristic absorbance, and FTIR analysis, which revealed functional peaks corresponding to glycosidic linkages (834.92 cm⁻¹), proteoglycan sugar rings (998.92 cm⁻¹), amide II (1617.66 cm⁻¹), and hydroxyl groups (3257.69 cm⁻¹). This work presents the first report of HA production by B. paralicheniformis, introducing a safe, efficient, and sustainable microbial platform as a promising potential alternative to traditional animal-derived or pathogenic sources for biomedical and cosmetic applications.

Storing biochar in soil is an effective method for improving the soil environment and reducing atmospheric greenhouse gases. Some strains of Bacillus species have been utilized as plant growth-promoting bacteria or biological control agents against plant diseases and pests. By colonizing biochar with beneficial bacteria, highly functional biochar that contributes to increased crop yields can be developed. In this study, we investigated the survival of type strains of eight Bacillus species (Bacillus amyloliquefaciens, B. licheniformis, B. nakamurai, B. pumilus, B. siamensis, B. subtilis, B. thuringiensis, and B. velezensis) in rice husk biochar, based on the sporulation state of vegetative cells or endospores. The bacterial density in the biochar significantly reduced when inoculated with a high concentration of vegetative cells, whereas it remained high when inoculated with a high concentration of spores. When water-washed biochar was inoculated with a high concentration of vegetative cells, survival significantly improved compared to that when unwashed biochar was inoculated. When a high concentration of vegetative cells was inoculated into the biochar water extract (biochar: water = 1:10), the bacterial densities of most species, except B. nakamurai and B. licheniformis, were significantly lower than those in alkali-sterilized water at pH 10.2 (same pH as biochar) and normal sterilized water (pH 6.7). These results suggest that the survival of Bacillus vegetative cells in biochar is inhibited by water-soluble inhibitors contained in the biochar rather than by alkaline conditions. When endospores were inoculated onto unwashed biochar, all strains maintained high viability for at least 12 weeks.

Antibiotic resistance and virulence factor of Helicobacter pylori pose formidable challenge towards eradication of this pathogen. Heterogeneity of H. pylori cagPAI is essential in the emergence of antibiotic resistance. The objective of this study was to investigate the correlation between antibiotic resistance and cagPAI variability among H. pylori strains in multiethnic Malaysian patients. H. pylori antibiotic susceptibility profile to six antibiotic classes was determined using E-test and the presence of each cagPAI gene was determined using polymerase chain reaction (PCR). The highest resistance was observed against metronidazole (58.6%, 34/58), followed by clarithromycin (36.2%, 21/58), and levofloxacin (25.9%, 15/58); all strains were susceptible to amoxicillin, tetracycline and rifampicin. Clarithromycin-resistance in H. pylori was significantly higher among elderly patients (> 50 years old) (P = 0.040). Isolates harboring complete cagT4SS genes exhibited significantly higher resistance to antibiotic treatments, primarily towards a single antibiotic (P = 0.043). Resistance to a single antibiotic was significantly higher in East Asian strains (P = 0.027), of which majority of the infected patients were Chinese. Among the resistant isolates, 20.9% (9/43) exhibited multi-drug resistance (MDR), demonstrating resistance to metronidazole, clarithromycin, and levofloxacin concurrently. Female patients were notably at higher risk of being infected with MDR-H. pylori (P = 0.022) than males. Our findings offer insights into the association between variability of cagPAI and antibiotic resistance in H. pylori, of which further research is warranted to elucidate the mechanisms underlying cagPAI heterogeneity and antibiotic resistance in H. pylori for effective therapeutic strategies.