International Biodeterioration & Biodegradation最新文献

This study focuses on an overlooked but critical issue: the composition and functional expression of microbial communities on the concrete surface in different areas of sewer pipes. Three immersion conditions were applied to simulate the duration of concrete in different areas ofsewers exposed to sewage, including short-term (L1), long-term (L2) and permanent immersion (L3). The properties of concrete under different immersion conditions and the bacterial diversity and functional capabilities in biofilms on the concrete surface were analyzed. Results showed that the L1 group was dominated by Halothiobacillus, whereas Desulfomicrobium was prominent in the L3 group. Significant differences in the predominant functional microbial communities and metabolic functional genes further confirmed the strong impact of immersion time on the pathways of microbial sulfur metabolism and concrete performance in sewer environment. Compared with the L2 and L3 groups, the decreased sewage immersion time resulted in an increase in the abundance and metabolic activity of sulfur-oxidizing bacteria in the L1 group. Hence, greater mass loss and gypsum production of concrete was found in the L1 group. The structural and functional differentiation of bacterial communities on the concrete surface observed in this study contributes to a better understanding of the uneven corrosion in real sewer pipes.

A halophilic multiple heavy metal-resistant bacterium, CdRPSD103, was isolated from the sea sediment and identified as Bacillus altitudinis strain CdRPSD103. This bacterial strain is able to tolerate and grow at high salt concentrations (up to 13% w/v NaCl). Biomass of Bacillus altitudinis CdRPSD103 is used in both live and dead conditions for Cd(II) biosorption. The effects of various operational parameters, such as pH, temperature, salinity, metal concentration, agitation speed, and biomass dosage, have been studied and optimised. Under optimal conditions, the removal of Cd(II) ranged from 99.45% to 55.24% using live biomass and from 98.81% to 53.13% using dead biomass, at Cd(II) concentrations ranging from 100 to 500 mg/L. The maximum biosorption (q_max) of Cd(II) was 280.2 and 269.6 mg per 1 g of live and dead biomass, respectively, at 500 mg/L of the initial Cd(II) concentration. The pseudo-second-order model was best fitted to this Cd(II) batch biosorption process and can be described as a two-step process (surface adsorption and intercellular accumulation). The adsorption isotherm was found in accordance with the Langmuir model, which represents the monolayer adsorption mechanism. Fourier transform infrared spectroscopy and field emission scanning electron microscopy with an energy dispersive X-ray analyses confirmed the possible interactions of bacterial cell surface ligands like hydroxyl, carbonyl carboxyl, and amine groups with Cd⁺² ions during the biosorption process by means of surface adsorption, ion exchange, and micro-precipitation. Transmission electron microscopic analysis confirmed the possible intracellular metal accumulation in live bacterial biomass. Therefore, CdRPSD103 is an effective bacterial strain for removing Cd(II) from saline metal-contaminated wastewater. The findings of this study can also be helpful for future widespread use of bacterial biomass, in both batch and continuous processes, to remove different hazardous metal ions from industrially polluted water systems.

The use of biostimulants to enhance microbial activity has been extensively reported. However, their regulatory properties on the ecological security of in situ composting have not yet been fully elucidated. Here, the effects of two biostimulants (fermentation agent [FM] and fulvic acid [FA]) on in situ composting were investigated under field conditions. The abundances of antibiotic resistance genes (ARGs), as well as those of the microbial communities and the activities of enzymes, were comprehensively investigated. The addition of biostimulants significantly reduced the abundances of streptomycin and sulfonamide resistance genes by 79%–97% and decreased the abundance of Gammaproteobacteria. This was particularly true for species that are members of the Enterobacteriaceae and contain many ARGs. The addition of biostimulants promoted the succession of bacterial communities toward enhancing the solubility of phosphorus, promoting the degradation of aromatic compounds, and reducing the emissions of NO_x gas. The application of FA and FM resulted in distinct bacterial network structures, and many negative correlations were associated with ARGs in the temperature subnetwork in the FM treatment. This study provides an effective strategy for the in situ treatment of agricultural waste and underscores the significance of biostimulants in improving the biological safety of medium-temperature in-situ composting.

While tremendous progress has been made in wastewater treatment, the primary focus has been on increasing the cost-effectiveness of treatment methods. Among these developments, anaerobic ammonia oxidation (anammox) has emerged as a key technology for efficiently removing nitrogen from wastewater. This review focuses on the operating circumstances of anammox processes, taking into account the unique system and types of anammox bacteria used. It addresses the many genera and species of anammox bacteria, as well as their growth characteristics and optimal operating circumstances. It investigates the individual wastewater types, sludge feed, and total nitrogen (TN) removal efficiency for each operation. This study explores strategies to optimize the growth and activity of anammox bacteria while addressing inhibitors and preservation techniques. It was found that the best temperature range for bacteria to grow is between 20 and 45 °C, the pH should be between 7.0 and 8.5, nitrite levels should be less than 100 mg/L, and DO levels should be less than 0.5 mg/L. It reveals sludge as the principal source of these bacteria, with dominant genes like Candidatus Brocadia and Candidatus Kuenenia showing more efficient growth compared to other anammox genera, and exhibiting a doubling time of 8–11 days in wastewater sludge environments. This study gives useful information about the operational characteristics and prospective benefits of anammox technology. The review helps to provide a full understanding of the anammox process and its potential for efficient nitrogen removal in wastewater treatment. Future research should focus on the effectiveness of biomass transporters and seeding sludge for rapid bacterial growth.

Sulfur cycle is an important material cycle in soil, and soil sulfur-metabolizing microorganisms are one of its prominent drivers. However, the fate of the sulfur cycle under the stressful condition of soil heavy metal pollution due to mining is unknown. In this study, three representative areas with low (L), medium (M) and high (H) levels of heavy metal pollution were selected to investigate the effects of heavy metal contamination levels on sulfur metabolizing microorganisms, sulfur cycling pathways and sulfur cycling genes by using metagenome sequencing and SCycDB sulfur cycle database annotation. The results showed that the relative abundance of sulfur cycle genes in the L, M, and H regions was 6.45 ± 0.12, 6.29 ± 0.15, and 5.75 ± 0.21, respectively; the abundance of sulfur cycle genes showed a decreasing trend with the increase of heavy metal pollution, and the sulfur cycle pathways and microbial sulfur metabolism were inhibited, and the dominant bacteria of the sulfur metabolizing bacterial community evolved gradually from Actinobacteria to Proteobacteria with abundances changing from 0.38 to 0.22 to 0.29 and 0.30, respectively; the proportion of sulfur cycle genes of different types in the sulfur metabolizing metabolizers did not vary with heavy metal pollution, indicating that different sulfur cycling genes in sulfur metabolizers show a uniform decline with increasing heavy metal pollution; dmsA may be a key gene mediating the adaptation and remediation of sulfur metabolizing bacteria to heavy metal pollution. The results reveal the effects of heavy metal pollution in mining areas on the sulfur cycle and provide new insights into the mechanisms of adaptation and remediation of heavy metal pollution by sulfur metabolizing microorganisms.

The shift from conventional wastewater treatment plants to biorefineries is one of the most environmentally and economically sustainable pathways for extracting valuable compounds from waste. Besides chemical-physical processes, microorganisms within sewage sludge utilize organic and inorganic pollutants in the wastewater as nutrients, leading to effective water purification. However, the remaining solid sludge residue, typically destined for specific landfills or incineration, could undergo microbial fermentation to produce volatile fatty acids (VFA), metabolic precursors for biopolymers. Increasing attention has been directed towards optimizing operational parameters to enhance VFA production during sewage sludge fermentation. This study examined the impact of potassium permanganate (PP) on microbial communities during the sewage sludge's acidogenic fermentation. The results highlighted the positive effect of PP treatment, which increased COD production and VFA yield up to 1263.5 mg/L and 664.2 mg COD/L, respectively. The presence of PP significantly enhances VFA yield promoting bacteria positively linked to VFA production.

Aflatoxin B1 (AFB1) is a potent mycotoxin and a common source of food and feed contamination, posing risks to both human and animal health. The biotransformation of AFB1 has been proven to be a promising approach to control AFB1 contamination. In this study, Brevundimonas sp. LF-1 capable of degrading AFB1 was isolated from a corn-planted soil sample. Strain LF-1 could degrade 86.90% of 2 mg L⁻¹ AFB1 after incubation in Luria-Bertani (LB) medium at 30 °C for 72 h and exhibited high performance when exposed to up to 10.0 mg L⁻¹ AFB1. The optimum pH and temperature were 7.0–10.0 and 30 °C, respectively. The results of the in vitro cytotoxicity assay showed that the degradation products had considerably (p < 0.05) less harmful effects than the parent AFB1. Additionally, strain LF-1 possessed the bioremediation potential of AFB1 contamination for biocontrol strategies in animal fodder. Two putative novel AFB1-degrading enzymes, peroxiredoxin 1 and peroxiredoxin 2, were identified in the genome of strain LF-1. Comparative genomics indicated that the peroxiredoxin enzyme was widely distributed in the genus Brevundimonas. The comprehensive examination of strain LF-1 has outstanding potential for the development of detoxifying agents for AFB1 in the food and feed industries.

Several physical and chemical methods have been developed for the remediation of a variety of toxic pollutants from soil. These methods may not be feasible and environmentally safe because of their high operational costs, energy requirements, and cause of secondary pollution. Bioremediation is a promising approach, but it is also a time-consuming process. Alternatively, the Bioelectrochemical system (BES) is an innovative technology for remediating diverse types of recalcitrant pollutants. However, there still exist some bottlenecks to BES for field-scale applications i.e., low mass transfer, poor electrical activity of anodes as electron acceptors, low bioavailability of organic matter, and limited beneficial bacterial activity. To overcome these challenges, various types of synthetic and natural surfactants have been investigated, though only biological surfactants like rhamnolipids were considered as possible interventions in terms of environmental safety. Therefore, this review of literature provides a brief overview of challenges associated with polluted soil remediation and describes currently available technologies including physico-chemical, biological and other available options. Subsequently, the advances of BES and their application for various types of pollutants remediation including petroleum hydrocarbons (PHs), polycyclic aromatic hydrocarbons (PAHs), azo dyes, pesticides, and polychlorinated biphenyls (PCBs) were comprehensively discussed. Further, the potential of rhamnolipid-assisted BES, its challenges and prospects to enhance bioremediation of soil pollutants were addressed.

Anthropization of Paleolithic karstic caves can cause an imbalance of cave microbiota and may trigger formation of wall alterations including black stains. In Lascaux Cave, a previous attempt to mechanically remove black stains was followed by reformation of the stain in months, suggesting that microbial recolonization had taken place. On this basis, we hypothesized that mechanical cleaning (a routine cleaning method for conservation of heritage sites) leaves a residual microbial community that can also serve as pioneer community, i.e. a community of early microbial residents that triggers subsequent microbial successions involved in the reformation of black stains. We monitored post-cleaning microbial recolonization over 19 months in the Apse of Lascaux Cave (France), after using two methods of mechanical cleaning (scalpel alone, or scalpel + sponge). Illumina MiSeq metabarcoding evidenced various taxa i.e. the bacteria Pseudomonas, Pedomicrobium and black-melanized fungi Ochroconis (=Scolecobasidium) during early recolonization of cleaned surfaces, and at later stages the establishment of several other taxa including the bacteria Luteimonas, Chitinophaga and the black fungus Exophiala. Surfaces at 19 months after cleaning were visually and microbiologically different from stained surfaces immediately after cleaned and from unstained surfaces, but also from non-cleaned stained surfaces, probably because of a particular microbial succession, distinct from the original succession during stain formation. Variations in relative abundance of Bacteroidota and Eurotiomycetes classes and Exophiala genus were higher when the sponge was used in addition to the scalpel. The bacteria Filomicrobium and the fungi Isaria and Cephalotrichum were identified on sponge-cleaned surfaces and on the sponge itself, pointing to a contaminant status due to the cleaning method. Overall, it suggests that post-cleaning pioneer communities may play an important role in orienting stain reformation in caves. Sponges routinely used by restorers to curb microbial stains may bring microbial contaminants, which questions current cleaning practices in show caves.

Urban river sediments often serve as reservoirs of halogenated aromatic pollutants, such as polychlorinated biphenyls (PCBs), leading to significantly alterations in the biological characteristics of this ecosystem. Various microbes can degrade halogenated aromatics, serving as a crucial detoxification mechanism that converts toxic pollutants into common metabolites to complete the carbon cycle. However, the impact of PCBs on the diversity and structure of microbial communities in urban rivers has remained largely unexplored. Understanding the dynamics of microbial community structure and function is essential for unraveling biodegradation pathways and interactions of these microbial degraders in PCB-contaminated urban river sediments. In this study, a thorough analysis of microbial diversity and distribution patterns was conducted using 16S rRNA gene-based sequencing in the sediments of two urban rivers, the Dasha River and Maozhou River. Our results unveiled distinct community variances between the two rivers, primarily influenced by environmental factors. The detailed composition and abundance of halogenated aromatic biodegradation related genes were elucidated using metagenomics, mainly contributed by Proteobacteria, Desulfobacterota, and Chloroflexi. Network analysis revealed close interactions among these microbes within each river, indicating a cooperative propensity for PCBs biodegradation, which underscores the interactions as the mode of metabolism and common survival strategy in contaminated rivers.