International Biodeterioration & Biodegradation最新文献

The microorganisms thriving in ageing Bauxite residue, or red mud, have captured scientific interest for their adaptability to extreme conditions. This study investigates extremophilic microbial communities present in Indian red mud for their potential to neutralize the residue and extracting metals. These communities thrive in the highly alkaline, sodic, and metal-rich conditions of this challenging environment. The research specifically highlights alkali-halophilic species and their ability to withstand pH fluctuations (7–11) and varying NaCl levels (0–3 M). Out of the 13 isolates analyzed, all preferred a pH range of 9–10 and tolerated NaCl up to 1.5–2 M. Notably, Evansella cellulosilytica and Halalkalibacterium halodurans, showed superior tolerance index for Al³⁺ and Cr⁶⁺ at 2000 ppm, as well as Co²⁺ at 1000 ppm, followed by Sutcliffiella cohnii. However, the tolerance index for Cu^2+, Te⁴⁺, and Hg²⁺ was relatively low for all tested strains. Additionally, Alkalihalobacillus sp. demonstrated remarkable tolerance to 10% red mud, facilitated by the production of mixed acids, neutralizing the pH within 24 h. The study proposes a potential mechanism for metal and red mud tolerance through genomic analysis using Rapid Annotation Subsystem Technology (RAST), revealing stress tolerance mechanisms, metal resistance genes, ion transporters, hydrolytic enzymes, siderophore production, and organic acid synthesis. Indigenous species like E. cellulosilytica, H. halodurans, S. cohnii, and Alkalihalobacillus sp. emerge as promising candidates for red mud bioremediation, providing insights into sustainable strategies for red mud disposal.

Consolidating polymeric materials are increasingly used for protection of the original artistic objects in museums and cultural heritage sites. Application of different polymeric materials onto outdoor cultural heritage objects requires careful evaluation and assessment in simulation and accelerated testing prior to any application being taken. Because of natural ecosystem, ambient microbiota together with the environmental factors (particularly sunlight, water/moisture, and water, such as wet-and-dry, and freeze-and-thaw cycles) is a key element that plays an important role to the integrity survival of the materials and cannot be ignored completely from application. The ecosystem-cultural heritage-microbial community continuum needs to be recognized with a clear holistic understanding of the framework or structure of this topic so that the science of it can be conducted meaningfully to serve the purpose to support the protection in a long run. Many of these basics are still missing while application is being made. This topic deserves serious attention to make fundamental progress in science.

This study advances the understanding of cellular damage and response mechanisms in Candida tropicalis (SHC-03) when exposed to toxic byproducts in corn stover hydrolysate, which is used for optimizing the industrial production of bioethanol and bio-based products. We found that the hydrolysate's toxic byproducts led to 84.61% accumulation of reactive oxygen species and considerable mitochondrial damage, thus inhibiting SHC-03 cell growth by 40%. The yeast combated these effects by enhancing the glutathione and thioredoxin systems, and increased their activity by 60% and 70%, respectively, to maintain intracellular redox balance. The ubiquitin–proteasome pathway was involved and endoplasmic reticulum stress was alleviated, which increased membrane thickness through ergosterol biosynthesis and improved inhibitor tolerance via upregulated expression of transporters and aldehyde reductases. These adaptations, along with the overexpression of genes related to the biosynthesis of impaired proteins and fatty acid degradation, promote SHC-03's resilience to hydrolysate toxic byproducts. Our findings could be useful for genetic modifications to increase the tolerance of fermentation strains, which could accelerate the industrial production of bioethanol and bio-based products.

This article covers the advancements and challenges in microbial remediation of polyaromatic hydrocarbons (PAHs), which are highly concerning pollutants due to their detrimental impacts on the environment and human health. It highlights the need for effective remediation methods in the face of rapid industrialization and expanding economies. Among the various approaches studied, microbial remediation has emerged as a promising, environmentally friendly, cost-effective, and sustainable strategy. However, the efficacy of microbial remediation is hindered by factors such as the ageing in the environment, toxicity of PAHs to microbial populations, the identification of more effective degradative enzymes, and the proliferation rate of degradative microbial strains in contaminated environments. Another constrain in biodegradation is the bioavailability of the PAHs which is primarily limited due to its low aqueous solubility and complex chemical structure. To address these challenges, innovative techniques such as multi-omics and genetic engineering have been employed to discover novel dehydrogenases and dioxygenases like catechol 2,3-dioxygenase gene responsible for PAHs degradation. The addition of microbial derived biosurfactants can be employed to address a major issue of PAHs bioavailability. Despite significant progress, the restoration of contaminated sites remains challenging due to the unfavourable environmental conditions encountered in real-world scenarios. This comprehensive communication aims to draw global attention to the hazardous nature of PAHs and shed light on the existing research gaps in order to guide future research endeavours in PAH degradation and remediation.

The bacterial community has received major attention in the research on the treatment of mariculture wastewater, while the fungal community has rarely been mentioned. To fill gap, an integrated bioremediation system (IBS) was built and the fungal community was identified by high-throughput sequencing in this study. Dimension reduction analysis, network analysis, community construction analysis were used to reveal the dynamic changes, interactions, and construction process of fungal communities in each treatment unit. The results showed that after a whole set of systematic and continuous treatments, the nutrient content in mariculture wastewater reached the lowest level. The fungal community was closely related to total nitrogen (TN), total phosphorus (TP), NO₃⁻-N, and NH₄⁺-N. In biofilm and shellfish units, Ascomycota was dominant, while in macroalgae units, Chytridiomycota was dominant. The community β-diversity of brush, ceramsite, and shellfish units showed similar trends in three time periods. In addition, some fungi showed a significant positive correlation with denitrifying bacteria, and this symbiotic relationship needs to be further studied. Finally, in the process of community construction, IBS was dominated by the stochastic process. This study aimed to more comprehensively interpret the dynamic changes of the microbial community in the mariculture wastewater treatment system and provided the theoretical reference for better understanding its potential mechanism and optimizing its process in the future.

The rapid development of agriculture has led to the production of a large amount of crop straw, necessitating effective strategies for its management. Microbial degradation offers a promising method. In this study, a novel microbial consortium composed of Phanerochaete chrysosporium, Aspergillus niger, and Streptomyces griseorubens, known for their robust lignocellulose degradation capabilities, was constructed for rice straw degradation. The establishment of this microbial consortium was based on the growth curve and antagonistic tests. Orthogonal optimization revealed that Streptomyces griseorubens played a predominant role in the degradation of rice straw. The optimal degradation conditions were determined as follows: nitrogen source concentration of 2.5 gL⁻¹, material-liquid ratio of 40 g L⁻¹, inoculum size of 3%, and pH value of 9. Under these conditions, the degradation efficiency reached 42% within 15 days. The decomposition of lignocellulosic components in the straw was confirmed through various characterization methods. Additionally, as the degradation process progressed, there was a noticeable decrease in protein-like substances and an increase in humic acid-like substances in the degradation solution.

Clostridioides difficile is a pathogenic anaerobe that potentially causes microbiologically influenced corrosion (MIC). Coupons of 304 stainless steel (SS) were incubated with C. difficile in deoxygenated brain heart infusion supplement medium. After a 7-d incubation, C. difficile biofilms were observed on the 304 SS coupon surfaces. The sessile cell count on 304 SS coupons were (1.9 ± 0.5) × 10⁷ cells/cm². It was found that this high-grade SS did not suffer measurable corrosion weight loss and pitting. X65 carbon steel was used to verify C. difficile bio-corrosivity. A 7-d weight loss of 0.9 ± 0.2 mg/cm² was found on X65 coupons with the same incubation condition, which manifested as uniform corrosion. 13%Cr steel, also known as 420 SS which is a low-grade SS that is prone to pitting, was used to verify pitting by C. difficile. A 15.2 μm pit was observed after 26 d of incubation. Electrochemical tests were conducted in a 10 mL biofilm/MIC test kit. The electrochemical analysis of electron mediator injection indicated that MIC of 304 SS by C. difficile belongs to extracellular electron transfer-MIC. A 100 ppm (w/w) tetrakis (hydroxymethyl)phosphonium sulfate (a green biocide) injection test proved that it is a suitable disinfectant for C. difficile.

Obtaining pure cultures and enrichment systems of methylotrophic anaerobic microorganisms capable of utilizing methyl compounds is critical to studying the carbon cycle in subsurface anoxic oil reservoirs. Culture-independent methods have been instrumental in uncovering the rich diversity of microorganisms in oil reservoirs. However, there remains a notable scarcity of methylotrophic microorganisms from oil reservoirs obtained by culture-dependent methods. In this study, we used five different methyl compounds, namely methanol, methylamine, dimethylamine trimethylamine, and methyl sulfide, as the sole substrates to isolate methyl-utilizing microorganisms from oil reservoirs, and H₂ was also added together with each of these methyl compounds in a separate isolation experiment, to facilitate H₂-dependent methylotrophic growth and metabolism. Notably, the highest colony numbers in roll tubes were achieved when using methanol as the substrate. A total of 306 pure strains, representing eight genera were obtained, and these microorganisms have rarely been reported for their ecological roles in oil reservoir systems. Following isolation, each strain was tested for utilization of methanol as the sole carbon and energy sources after a second transfer, including headspace gas assay and microbial cell observations. In addition, enrichment cultures amended with each of the five different methyl compounds with or without the addition of H₂ gas were established from four oil reservoir samples. Further experiments showed that the archaea enriched with methyl substrates from different oil reservoirs were almost all Methanobacteria, but after adding H₂, the H₂-dependent methylotrophic methanogen Ca. Methanomethylica was enriched in most of the enrichment cultures. On the contrary, the addition of H₂ has less impact on the bacterial communities. The isolation of pure cultures has significantly enhanced our understanding of the diversity and ecophysiology of methylotrophic microorganisms in oil reservoirs. This study has provided useful insights into methyl-based methane generation within oil reservoirs, contributing to further understanding of the microbial ecology and carbon cycle in anoxic oil reservoirs.

Arsenic (As) represents a hazardous, carcinogenic substance transported in the food chain causing severe health issues. Several technologies are implemented to minimize arsenic accumulation and toxicity to plants and soil. Traditional arsenic remediation methodologies utilize soil washing, land filling, and chemical stabilization. Soil microorganisms’ applications render cost-effective and eco-friendly arsenic toxicity alleviation. Microorganisms-mediated methods have gained momentum over traditional remediation in recent years. Arbuscular mycorrhizal fungi (AMF) are predominant microorganisms forming symbiosis with terrestrial plant roots. AMF mycelium interacts with the rhizosphere network and improves essential nutrient acquisition, water absorption, and plant growth. AMF also accounts for stress management and plant protection. Directly or indirectly AMF mitigates arsenic metal stress through plant growth and augmented physiological mechanisms. The AMF-mediated arsenic toxicity management encompasses the symbiosis between AMF and host plant. AMF mycelium acts as a metal sink and reduces soil arsenic concentrations, accumulation, and translocation of arsenic in roots and shoots. Thus, AMF inoculation reduces arsenic mobilization and increases arsenic biological dilution. Consequently, arsenic accumulation induces a decrease in oxidative stress. AMF aids the host plant growth and maintains the phosphate/arsenate ratio in the plant tissues. Thereby, a suitable environment is created in arsenic-contaminated soils by AMF. Environmental management of As toxicity, tolerance, and remediation strategies are correlated for sustainable agriculture.

Ex situ bioremediation of crude oil in bioreactors by oleophilic bacteria permits to regulate temperature, nutrients and oxygen and the results in petroleum removal are much more effective than in situ bioremediation. This article quantify the biodegradation of alkanes which conform crude oil in bioreactors by three oleophilic strains. Samples were collected from the bioreactors and extracted in dichloromethane (10:1 aqueous/organic v/v) for amplification in GC-FID analysis of individual alkanes. 94% of crude oil (initial concentration 8.6 g l⁻¹) is removed in 24 days by Bacillus licheniformis and in 38 days by Pseudomonas putida and Paenibacillus glucanolyticus. Higher biodegradation rates (9.0–26.5 mg l⁻¹d⁻¹) are reached for the lightest fraction of crude oil by Bacillus licheniformis (C10–C16), and much lower for C22–C25 alkanes (4.4–8.9 mg l⁻¹d⁻¹). Pseudomonas putida and Paenibacillus glucanolyticus degrade a wide range of alkanes at 1.6–9.6 mg l⁻¹d⁻¹, with preference over C8–C16 hydrocarbons. Heptane and octane (alkanes cited to be toxic) are difficult for biodegradation in two strains (B. licheniformis and P. putida) and a recalcitrant “window” C18–C21 is observed for the three oleophilic strains in the alkane range studied.