Physicochemical and molecular characterization of heavy metal-tolerant bacteria isolated from soil of mining sites in Nigeria

Background

Mining for precious metals is detrimental to the composition of soil structure and microbial diversity distribution and is a health risk to human communities around the affected communities. This study was aimed at determining the physical and chemical characteristics and diversity of bacteria in the soil of local mining sites for biosorption of heavy metals.

Results

Results of physical and chemical characteristics showed mean pH values and percentage organic carbon to range from 7.1 to 8.2 and 0.18 to 1.12% respectively with statistical significance between sampling sites (P ≤ 0.05). Similarly, cation exchange capacity, electrical conductivity, moisture, total nitrogen, and carbon/nitrogen ratio (C:N) in the soil ranged between 1.52 to 3.57 cmol/kg, 0.15 to 0.32 ds/m, 0.14 to 0.82%, 0.10 to 0.28%, and 1.7 to 4.8 respectively. The highest heavy metal concentration of 59.01 ppm was recorded in soils obtained from site 3. The enumeration of viable aerobic bacteria recorded the highest mean count of 4.5 × 10⁶ cfu/g observed at site 2 with statistical significance (P ≤ 0.05) between the sampled soils. Alcaligenes faecalis strain UBI, Aeromonas sp. strain UBI, Aeromonas sobria, and Leptothrix ginsengisoli that make up 11.2% of total identified bacteria were able to grow in higher amended concentrations of heavy metals. The evolutionary relationship showed the four heavy metal–tolerant bacteria identified belonged to the phylum Proteobacteria of class Betaproteobacteria in the order Burkholderiales. Heavy metal biosorption by the bacteria showed Alcaligenes faecalis strain UBI having the highest uptake capacity of 73.5% for Cu.

Conclusion

In conclusion, Alcaligenes faecalis strain UBI (MT107249) and Aeromonas sp. strain UBI (MT126242) identified in this study showed promising capability to withstand heavy metals and are good candidates in genetic modification for bioremediation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s43141-021-00251-x.

Functional Outcome of Surgical Stabilisation of Acetabular Fractures

Introduction:

Approach to the management of displaced acetabular fractures has evolved from conservative to operative management after the work of Judet and Letournel. Various surgical methods have been explored and described by authors to address this type of fracture, leading to improved clinical outcome. This study aimed to evaluate functional outcome of surgically treated displaced acetabular fractures in the Malaysian context.

Materials and methods:

We analysed 43 patients with isolated acetabular fractures who were treated operatively with a minimum of three years follow-up. Anthropometric data, Judet-Letournel fracture pattern, surgical approach and complications were recorded. Post-operative Matta radiological outcome were evaluated for joint congruency and hip functional outcome was evaluated using Merle d’Aubgine-Postel and Harris Hip Score (HHS). All statistical analyses were analysed using SPSS version 24.0.

Results:

The most frequent elementary fracture type was posterior wall (30.2%) while associated type was both columns (23.3%). Mean functional outcome of Merle d'Aubigné-Postel was 15.77 and HHS was 86.6. Thirty-three (76.7%) patients achieved satisfactory functional outcome, 19 (44.1%) patients achieved anatomic reduction (<2 mm step-off) based on Matta classification while 24 (55.8%) did not achieve the desired outcome. Fracture pattern exhibited strong association with post-operative Matta radiological outcome (p-value 0.001). However both fracture pattern and Matta radiological outcome did not exhibit association with the functional outcome group. The mean time for surgical interventions was 10.8 days and there was no significant association with final functional outcome score.

Conclusion:

Fracture pattern is a strong contributing factor towards post-operative Matta radiological outcome. However, achieving the perfect anatomical reduction is not of utmost important factor to predict the good functional outcome.

Functional Outcome after Treatment of Aggressive Tumours in the Distal Radius: Comparison between Reconstruction using Proximal Fibular Graft and Wrist Fusion

Introduction: Restoration of a functional hand is the ultimate goal following a distal radius tumour resection. The early outcomes of mobile wrist reconstruction are satisfactory; however, long-term results are unpredictable due to late wrist instability and degenerative arthritis. Our aim is to compare mobile wrist reconstruction with wrist fusion (pan-carpal fusion) in our cohort of patients.

Materials and Methods: A retrospective cohort study was performed for functional outcomes of all patients who underwent resection for distal radius tumour and treated with either fusion or reconstruction of the wrist in a single institution from years 2000-2013 with a minimum of three years follow-up.

Results: Eleven patients were included in the study, six of whom had wrist reconstruction with proximal fibula graft and the remaining five wrist fusion, with a mean follow-up of 6.3 years. The mean Musculoskeletal Tumour Society (MSTS) score was 82.78%, ranging from 70% to 93.3%. Average grip strength compared to the normal contralateral hand was 60.0% for total wrist fusion, which was better than wrist reconstruction with 58.07%. There was no difference in the functional outcome between fusion and mobile reconstruction in our study. Osteoarthritis changes and subluxation of the wrist joint were the most common findings in the long-term follow-up for this group.

Conclusion: There was no difference in the functional outcome of the long-term follow-up between the two groups.

Field evaluation of cypermethrin and cyfluthrin against dengue vectors in a housing estate in Malaysia

Cynoff 25ULV (cypermethrin 25 g/l) and Solfac UL015 (cyfluthrin 1.5% w/v) were evaluated against the sentinel sugar-fed adults and 4th-instar larvae of Aedes aegypti in a housing estate endemic of dengue in Malaysia. The impact of both pyrethroids on field populations of Aedes albopictus and Aedes aegypti larvae was monitored weekly using bottle containers. Both Cynoff 25ULV and Solfac UL015 showed adulticidal effects and larvicidal effects. This field trial using Cynoff 25ULV against dengue vectors showed its potential for use in dengue vector control programs.