The study was conceived with the objective to isolate and characterize lytic bacteriophages (phages) against Staphylococcus aureus (S. aureus) associated with bovine mastitis. Phages were isolated from enriched slurry and milk samples using the agar overlay technique. Characterization included plaque morphology, Field Emission Scanning Electron Microscopy (FE-SEM), pH and thermal stability, host range (spot assay), adsorption assay and one-step growth curve analysis. Lytic efficacy was assessed using the Efficiency of Plating (EOP) method. Five phages (pS1 to pS5) were isolated, of which pS4 and pS5 were temperate phages as indicated by its lysis pattern. The analysis showed that phages pS2 and pS3 produced clear, pinpoint-sized plaques while pS1 formed large, clear plaques. FE-SEM classified all three phages under the class Caudoviricetes. Adsorption assay and one step growth curve analysis revealed that the phages had an adsorption time ranging from 9 to 15 min, and a latent period between 30 and 50 min and burst sizes of 68 (pS2), 220 (pS1) and 280 (pS3) pfu/cell. Stability tests revealed significant difference in thermal stability at 60 °C and 70 °C (p < 0.0001), and in pH tolerance from pH 2 to 10 (p < 0.0001) among pS1, pS2 and pS3. The spot assay revealed that the complete panel of clinical S. aureus isolates (n = 18), standard cultures (ATCC 12600 and ATCC 29213) and clinical isolates of S. chromogenes and S. haemolyticus were sensitive to pS1. In contrast, pS2 and pS3 exhibited lytic activity exclusively against the S. aureus isolates, showing no activity against S. chromogenes or S. haemolyticus. Phage pS1 demonstrated good lytic effect against 10/21 test isolates compared to pS2 (3/21) and pS3 (3/21). Overall, the study characterized three lytic phages targeting S. aureus implicated in bovine mastitis and showed its in vitro efficacy against planktonic S. aureus.

2025-07-01·JOURNAL OF HAZARDOUS MATERIALS

Distinct mechanisms of stibnite (Sb2S3) oxidative dissolution mediated by acid-generating and alkali-generating microorganisms within a wide pH range

Article

作者: Gao, Weikang ; Zhang, Jingkang ; Sapsford, Devin J ; Chen, Liran ; Lu, Xiaolu ; Wang, Hongmei ; Wang, Xingjie ; Zhou, Jianwei ; Ma, Liyuan

Indigenous microorganisms in antimony mining areas facilitate stibnite dissolution over a wide pH range, yet their mechanisms remain poorly studied. Herein, the acid-generating Bosea sp. AS-1 and the alkali-generating Pseudomonas sp. PS-3 were selected to interact with stibnite (Sb₂S₃) under initial acidic (pH value = 5) and alkaline (pH value = 8) conditions, respectively. Results indicated that AS-1 and PS-3 promoted stibnite dissolution compared to the sterile control irrespective of initial pH conditions, but through distinct mechanisms. AS-1 oxidized sulfide to sulfate by regulating the expression of SoxB and SoxC genes, thereby driving the stibnite dissolution and oxidation. Up to 18.63 mg/L total antimony (Sb(tot)) was released and the dissolved Sb(III) was completely oxidized to Sb(V). Moreover, AS-1 prevented the passivation layer formation by inhibiting sulfur oxidation intermediates accumulation. Conversely, PS-3 could not oxidize sulfur, but produced more extracellular polymeric substances which bound microorganisms closely to stibnite. The stibnite dissolution was facilitated through pH elevation from 5.0 to above 9.0 mediated by PS-3, releasing up to 35.56 mg/L Sb(tot). However, the accumulated sulfur oxidation intermediates facilitated the passivation layer formation, inhibiting further dissolution of stibnite. Additionally, less than 44 % of the soluble Sb(III) was oxidized to Sb(V). These results contribute to understanding the microbial-mediated transformation, mobilization and oxidation of antimony.

2025-02-01·DERMATOLOGIC SURGERY

Impact of Needle Design and Suture Gauge on Tissue Tearing During Skin Suturing: A Comparative Analysis

Article

作者: Potter, Christian T. ; Riopelle, Alexandria M. ; Fudem, Gary M. ; Schanbacher, Carl F. ; Maloney, McKenzie E.

BACKGROUND:

Surgeons face numerous choices in selecting sutures for skin closure, with potential adverse effects such as tissue tearing.

OBJECTIVE:

To investigate the influence of needle design and suture gauge on tissue tearing during suturing procedures.

MATERIALS AND METHODS:

The authors tested the tear-through force in Newtons for 3 needle types and 3 suture gauges using an artificial skin model and a professional-grade tensiometer. Suture material was secured into the skin model, and force was applied to the suture at a constant rate, resulting in tearing. Force–displacement and force–time curves were generated. Evaluation included conventional cutting (PC-3), reverse cutting (PS-3), and taper point (BB) needles with a 5-0 polypropylene suture. In addition, nylon sutures with a reverse cutting needle (PS-2) were tested at 3 suture gauges (5-0, 4-0, 3-0).

RESULTS:

The mean tear-through forces for PC-3, PS-3, and BB were 3.26 N, 3.75 N, and 4.07 N, respectively. For the 5-0, 4-0, and 3-0 nylon sutures, the mean tear-through forces were 3.44 N, 3.81 N, and 4.04 N, respectively. Statistical analysis revealed a significant impact of suture gauge size (p < .001) and needle geometry (p < .001) on tear-through force.

CONCLUSION:

Larger suture diameter and taper needles minimize tissue tearing.

100 项与 PS-3 相关的药物交易

登录后查看更多信息