Inoculation of cadmium-tolerant bacteria to regulate microbial activity and key bacterial population in cadmium-contaminated soils during bioremediation.

The perennial ryegrass Lolium perenne can be used in conjunction with cadmium (Cd)-tolerant bacteria such as Cdq4-2 (Enterococcus spp.) for bioremediation of Cd-contaminated soil. In this study, a theoretical basis was provided to increase the efficiency of L. perenne remediation of Cd-contaminated soil using microorganisms to maintain the stability of the soil microbiome. The experimental design involved three treatment groups: CK (soil without Cd addition) as the control, 20 mg·kg-1 Cd-contaminated soil, and 20 mg·kg-1 Cd-contaminated soil + Cdq4-2, all planted with L. perenne. The soil was collected on day 60 to determine the soil microbial activity and bacterial community structure and to analyze the correlation between soil variables, the bacterial community, available Cd content in the soil, Cd accumulation, and L. perenne growth. The soil microbial activity and bacterial community diversity decreased under Cd stress, and the soil microbial community composition was changed; while inoculation with Cdq4-2 significantly increased soil basal respiration and the activities of urease, invertase, and fluorescein diacetate (FDA) hydrolase by 83.65%, 79.72%, 19.88%, and 96.15% respectively; and the stability of the community structure was also enhanced. The Actinobacteriota biomass, the amount of available Cd, and the above- and belowground Cd content of L. perenne were significantly negatively correlated with the total phosphorus, total potassium, and pH. The activity of urease, invertase, and FDA hydrolase were significantly positively correlated with the biomasses of Acidobacteriota and L. perenne and significantly negatively correlated with the Chloroflexi biomass. Further, the available soil Cd content and the above- and belowground Cd levels of L. perenne were significantly positively correlated with the Actinobacteriota biomass and significantly negatively correlated with the Gemmatimonadetes biomass. Overall, inoculating Cd-tolerant bacteria improved the microbial activity, diversity, and abundance, and changed the microbial community composition, facilitating the remediation of Cd-contaminated soil by L. perenne.

A Comprehensive Study on Implant Stability Quotient (ISQ) in View of Resonance Frequency and Spectrum Analysis.

PURPOSE: This experimental study investigated how well implant stability quotient (ISQ) represents resonance frequency. Benchtop experiments on standardized samples, mimicking a premolar section of a mandible, were conducted to correlate an ISQ value and a resonance frequency to synthetic bone density and an incremental insertion torque. A frequency spectrum analysis was performed to check the validity of the resonance frequency analysis (RFA). MATERIALS AND METHODS: Branemark Mk III implants with dimensions ∅4 Å~ 11.5 mm were placed in Sawbones test models of five different densities (40, 30, 40/20, 20, 15 PCF). An incremental insertion torque was recorded during implant placement. To perform stability measurements, the test models were clamped partially in a vise (unclamped volume 10 Å~ 20 Å~ 34 mm). A MultiPeg was attached onto the implants, and a Penguin RFA measured ISQ. Simultaneously, motion of the MultiPeg was monitored via a laser Doppler vibrometer and processed by a spectrum analyzer to obtain the resonance frequency. Tightness of the clamp was adjusted to vary the resonance frequency. A statistical analysis produced a linear correlation coefficient 𝑅 among the measured ISQ, resonance frequency, and incremental insertion torque. RESULTS: The resonance frequency had high correlation to the incremental insertion torque (𝑅 = 0.978), confirming the validity of using RFA for this study. Measured ISQ data were scattered and had low correlation to the resonance frequency (𝑅 = 0.214) as well as the incremental insertion torque (𝑅 = -0.386). The spectrum analysis revealed simultaneous presence of multiple resonance frequencies. CONCLUSIONS: For the designed benchtop tests, resonance frequency does indicate implant stability in view of Sawbones density and incremental insertion torque. ISQ measurements, however, do not correlate well to the resonance frequency, and may not reflect the stability when multiple resonance frequencies are present simultaneously.

Vonoprazan-amoxicillin dual therapy with different amoxicillin dosages for treatment-naive patients of Helicobacter pylori infection in China: a prospective, randomized controlled study.

BACKGROUND: The vonoprazan (VPZ)-amoxicillin (AMO) dual therapy (VA) demonstrates a satisfactory eradication rate for Helicobacter pylori (H. pylori ). However, the optimal dosage of AMO in this regimen remains uncertain. The objective of this study is to investigate the efficacy of different doses of AMO in the VA regimen for first-line treatment of H. pylori infection. METHODS: A total of 192 treatment-naive H. pylori -infected patients were randomly assigned to one of three groups: low-dose VA (LD-VA: VPZ 20 mg b.i.d + AMO 750 mg t.i.d), moderate-dose VA (MD-VA:VPZ 20 mg b.i.d + AMO 1000 mg t.i.d), and high-dose VA (HD-VA: VPZ 20 mg b.i.d + AMO 1250 mg t.i.d). All groups received 14 days of treatment. The study evaluated and compared the eradication rates, adverse events (AEs), and patient compliance among the three groups. RESULTS: Eradication rates for LD-VA, MD-VA, and HD-VA were 76.6% (49/64), 79.7% (51/64), and 84.4% (54/64), respectively, as determined by intention-to-treat analysis; 90.6% (48/53), 94.3% (50/53), and 98.1% (53/54) according to per-protocol analysis; 89.1% (49/55), 94.4% (51/54), and 96.4% (54/56) with modified intention-to-treat analysis (all P  > 0.05). Although not statistically significant, numerically higher eradication rates were observed with the higher dose AMO VA regimen. There were no statistically significant differences in the incidence of AEs and compliance among the three VA regimens. CONCLUSION: Fourteen-day VA regimens with AMO doses exceeding 2 g/day demonstrated satisfactory eradication rates. HD-VA therapy is potentially the most effective regimen. Large-sample clinical trials are required to further validate these findings.

Biochar loaded with ferrihydrite and Bacillus pseudomycoides enhances remediation of co-existed Cd(II) and As(III) in solution.

Bioremediation is one of the effective ways for heavy metal remediation. Iron-modified biochar (F@BC) loaded with Bacillus pseudomycoides (BF@BC) was synthesized to remove the coexistence of cadmium (Cd) and arsenic (As) in solutions. The results showed that B. pseudomycoides significantly increased the removal rate of Cd(II) by enhancing the specific surface area and Si-containing functional groups of biochar (BC). The surface of F@BC was enriched with Fe-containing functional groups, significantly improving As(III) adsorption. The combination of ferrihydrite and strains on BF@BC enhanced the removal of Cd(II) and As(III). It also promoted the oxidation of As(III) by producing an abundance of hydroxyl radicals (·OH). The maximum saturated adsorption capacity of BF@BC for Cd(II) and As(III) increased by 52.47% and 2.99 folds compared with BC, respectively. This study suggests that biochar loaded with Fe and bacteria could be sustainable for the remediation of the coexistence of Cd(II) and As(III) in solutions.

Investigating the Mechanism of Cadmium-Tolerant Bacterium Cellulosimicrobium and Ryegrass Combined Remediation of Cadmium-Contaminated Soil.

Cadmium (Cd) pollution has been rapidly increasing due to the global rise in industries. Cd not only harms the ecological environment but also endangers human health through the food chain and drinking water. Therefore, the remediation of Cd-polluted soil is an imminent issue. In this work, ryegrass and a strain of Cd-tolerant bacterium were used to investigate the impact of inoculated bacteria on the physiology and biochemistry of ryegrass and the Cd enrichment of ryegrass in soil contaminated with different concentrations of Cd (4 and 20 mg/kg). The results showed that chlorophyll content increased by 24.7% and 41.0%, while peroxidase activity decreased by 56.7% and 3.9%. In addition, ascorbic acid content increased by 16.7% and 6.3%, whereas glutathione content decreased by 54.2% and 6.9%. The total Cd concentration in ryegrass increased by 21.5% and 10.3%, and the soil's residual Cd decreased by 86.0% and 44.1%. Thus, the inoculation of Cd-tolerant bacteria can improve the antioxidant stress ability of ryegrass in Cd-contaminated soil and change the soil's Cd form. As a result, the Cd enrichment in under-ground and above-ground parts of ryegrass, as well as the biomass of ryegrass, is increased, and the ability of ryegrass to remediate Cd-contaminated soil is significantly improved.