Evariste Bosco Gueguim Kana

This study assesses the kinetics of Tandemol lubricant degradation by Pseudomonas synaxantha rhizo‐25 after UV treatment and nanoparticle inclusion. The degradation efficiency was assessed in terms of the Total Petroleum Hydrocarbons (TPH) and aromatic compounds degraded in a liquid medium containing Tandemol lubricant. The medium composition was further supplemented with nanoparticles to evaluate their impact on the process. Metabolite profiling was conducted using Gas Chromatography‐Mass Spectrometry (GC‐MS), while transcriptomic analysis identified key enzymes involved in the degradation process. For TPH degradation, biodegradation rate ( K ) and half‐life ( t _1/2 ) values were found to be −0.39 M ⁻¹ day ⁻¹ and 10.22 days (wildtype), and 0.013 M day ⁻¹ and 9.33 days (UV‐treated), respectively. For the aromatic compounds, the estimated K and t _1/2 values were −63.30 M ⁻¹ day ⁻¹ and 7 h (wildtype), and −0.69 day ⁻¹ and 1.01 days (UV‐treated). The nanoparticle supplemented aromatic degradation yielded K and t _1/2 values of −21.01 M ⁻¹ h ⁻¹ and 0.85 h (UV‐treated). Aromatic compound degradation was observed to follow the meta‐cleavage pathway with terminal oxidation as an activation mechanism. Oxidoreductases, namely Cytochrome P450 and Tau D/Tfd A dioxygenase, were responsible for the primary step in the degradation pathway. Overall, these results showed that the UV treatment and the inclusion of nanoparticles enhanced biodegradation efficiency towards optimum petroleum contaminant bioremediation.

Oil pollution remains a persistent global environmental challenge due to the recalcitrance and toxicity of lipid-rich contaminants in terrestrial and aquatic ecosystems. Bacterial lipases (EC 3.1.1.3) play a pivotal role in the initial stages of bioremediation by catalysing the hydrolysis of complex lipids into more bioavailable intermediates, thereby facilitating downstream microbial degradation and mineralisation. This review critically examines the mechanistic basis of lipase-mediated hydrocarbon degradation, with emphasis on enzyme structure–function relationships, catalytic pathways, and regulation under environmentally relevant conditions. In addition to conventional applications in soil and wastewater bioremediation, emerging strategies involving immobilised enzymes, microbial consortia, and waste-derived substrates are evaluated for their effectiveness and scalability. Attention is given to advances in molecular and omics approaches, including metagenomics, transcriptomics, and proteomics, which have expanded the discovery of novel lipases but remain limited in their ability to predict in situ functionality. The review highlights the growing role of protein engineering and artificial intelligence in tailoring lipase properties; however, it also critically assesses current limitations, including insufficient experimental validation and challenges in translating computational predictions to complex environmental systems. Furthermore, integrating multi-omics data into quantitative and predictive frameworks is identified as a key future direction for improving bioremediation efficiency. Despite significant progress, major gaps persist in linking enzyme activity to real-world degradation performance and in developing standardized, scalable approaches. This review therefore provides a comprehensive and critical synthesis of current knowledge while identifying strategic research priorities required to advance bacterial lipases as robust tools for sustainable bioremediation of lipid-based pollutants.

This study explored the scale-up and kinetic dynamics of simultaneous saccharification and co-fermentation (SSCF) of bioethanol from detoxified PPW hydrolysate using the co-culture of Saccharomyces cerevisiae and Pichia stipitis. The 13L pilot-scale bioreactor (with 10L working volume) was operated at a rotational speed of 1.58 rps, with an impeller tip speed (Vtip) of 0.35 m/s, and a power input of 0.012W, closely replicating the hydrodynamic conditions of the 2L laboratory-scale bioreactor (with 1L working volume) operated at 2.0 rps, Vtip of 0.35 m/s, and 0.012W. This resulted in high bioethanol concentration (43.62 g/L), yield (0.472 g/g), and conversion efficiency (92.4%), which significantly reduced specific power consumption to 1.2 W/m3. The power consumption per unit volume (P/VL) was 10-fold lower compared to the P/VL obtained in the 2 L bioreactor. Meanwhile, a 0.79-fold decrease in shear stress was achieved in pilot pilot-scale bioreactor, resulting in low cell damage. The kinetic models implemented fitted the experimental data for the cell biomass production, bioethanol production, and substrate utilization, with coefficient of determination (R2) close to 1. The bioethanol production was predominantly growth-associated, as indicated by higher α (g ethanol/g substrate) than β (g ethanol/g substrate/h) values. Furthermore, the derived nutrient-rich effluent, with a high total organic carbon (TOC) content (78% g/g), holds potential for cultivating microalgae. These findings provide valuable insights for industrial bioprocesses design and optimizing large-scale sustainable bioethanol production, and the downstream valorisation potentials of fermentation effluents.

Lignocellulosic-based (LCB) bioethanol production is challenged by the presence of inhibitory compounds in pretreated LCB hydrolysates limiting productivity. The negative impact of these inhibitory compounds on LCB bioethanol production kinetics remain understudied. Hence, this study modelled the kinetics of bioethanol fermentation using nanoadsorbent-detoxified potato peel waste (PPW) hydrolysate. Four different fermentation processes under both separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) conditions, including A (SHF with non-detoxified hydrolysate), B (SSF with non-detoxified hydrolysate), C (SHF with detoxified hydrolysate), and D (SSF with detoxified hydrolysate) were evaluated for bioethanol productivity. Higher productivity of 1.23 and 1.16-fold increments were recorded for fermentation processes C and D. Thereafter, the experimental data for cell growth, bioethanol production and substrate utilisation were well-fitted by the logistic function, modified Gompertz, and Luedeking-Piret models respectively. Moreover, the obtained root-mean-square error (RMSE) and mean square error (MSE) were low, while the accuracy factor (AF), bias factor (BF), slope and regression coefficient (R²) were close to 1. The bioethanol production processes were largely growth-associated (α) as α values (g ethanol/g substrate) were higher than β values (g ethanol/g substrate/h). The models were effectively implemented, demonstrating their usefulness to elucidate bioethanol productivity kinetics for improved process design and the development of large-scale bioethanol production. Graphical Abstract

This study reports on the effects of pretreated biogas slurry on degraded farm soil properties, microflora and the production of Capsicum spp. The responses of soil properties, microorganisms and Capsicum spp. production to biogas slurry pretreated soil were determined. The biogas slurry pretreatment of degraded soil increases the total nitrogen (0.15–0.32 g/kg), total phosphorus (0.13–0.75 g/kg), available phosphorus (102.62–190.68 mg/kg), available potassium (78.94–140.31 mg/kg), organic carbon content (0.67–3.32 g/kg) and pH value of the soil, while the population, diversity and distribution of soil bacteria and fungi were significantly affected. Interestingly, soil ammonium nitrogen, soil pH and soil nitrate nitrogen were highly correlated with the population of bacteria and fungi present in the pretreated soil. The soil with biogas slurry pretreatment of 495 m³/hm² favored the seedling survival rate, flowering rate and fruit-bearing rate of Capsicum spp. and significantly reduced the rate of rigid seedlings. In this study, the application of 495 m³/hm² biogas slurry to pretreat degraded soil has achieved the multiple goals of biogas slurry valorization, soil biofertilization and preventing and controlling plant diseases caused by soil-borne pathogenic microorganisms. These findings are of significant importance for the safe and environmentally friendly application of biogas slurry for soil pretreatment.

Biogas slurry (BS) is an attractive agricultural waste resource which can be used to regulate soil microbial communities, enhance nutrient absorption capacity of crops, promote plant–soil interactions, and consequently, increase crop productivity. Presently, BS discharge is not environmentally friendly. It is therefore necessary to explore alternative efficient utilization of BS. The use of BS as fertilizer meets the requirements for sustainable and eco-friendly development in agriculture, but this has not been fully actualized. Hence, this paper reviewed the advantages of using BS in farmland as soil fertilization for the improvement of crop production and quality. This review also highlighted the potential of BS for the prevention and control of soil acidification, salinization, as well as improve microbial structure and soil enzyme activity. Moreover, this review reports on the current techniques, application methods, relevant engineering measures, environmental benefits, challenges, and prospects associated with BS utilization. Lastly, additional research efforts require for optimal utilization of BS in farmlands were elucidated.