Glycine betaine enhances biodegradation of phenol in high saline environments by the halophilic strainOceanobacillussp. PT-20

The Mechanism Underlying Enhanced Coal-to-Methane Conversion in Anaerobic Digestion With Betaine Supplementation

Anaerobic digestion (AD) of coal-to-methane technology represents a promising energy conversion method that not only reduces environmental pollution but also contributes to sustainable development. However, low methane conversion efficiency remains a major challenge. This study investigates the use of betaine, a green and environmentally friendly alkaloid, to enhance the AD process of coal. Our results demonstrate that betaine supplementation increases the relative abundance of key microbial populations, including Petrimonas, Desulfitibacter, Methanoculleus, and Methanosarcina, while also improving cell membrane permeability. Three-dimensional fluorescence characterization reveals elevated secretion of bacterial metabolites, leading to increased protein concentrations and enhanced enzymatic activity in the liquid phase. Moreover, the content of alkane compounds in the liquid phase increases, further confirming the enhanced conversion of coal to biological methane. In conclusion, betaine supplementation significantly improves coal AD efficiency, providing a novel approach to optimize coal fermentation and biological energy conversion.

Enhanced undecylprodigiosin production using collagen hydrolysate: a cost-effective and high-efficiency synthesis strategy

Undecylprodigiosin (UDP), a desirable pyrrole-based biomaterial, holds significant promise in pharmaceutical and medical applications due to its diverse biological activities. However, its application is usually hampered by low synthesis efficiency and high production costs. Here, we developed a high-efficiency and cost-effective strategy for UDP synthesis using collagen hydrolysate (COH) as a readily available and abundant precursor source in conjunction with Streptomyces sp. SLL-523. COH obviously accelerated the proliferation of Streptomyces sp. SLL-523. Replacing muscle hydrolysate with COH resulted in a 7-fold increase in UDP yield and a 10-fold reduction in fermentation time, indicating that COH significantly enhanced the synthesis efficiency of UDP. Besides, COH remarkably increased the intracellular levels of UDP precursor amino acids (AAs). Whole-genome analysis of Streptomyces sp. SLL-523 revealed the gene clusters responsible for UDP synthesis and COH utilization. COH markedly stimulated the expression of genes involved in the metabolism pathways of energy, transporters, peptides, and AAs, ultimately promoting the UDP synthesis. Significantly, COH efficiently triggered and boosted the expression of key genes in the UDP biosynthesis pathway, including redQ, redM, redN, and redL, leading to highly efficient UDP synthesis. Thus, this innovative approach provides a novel framework for the high-efficiency synthesis of natural pyrrole biomedical materials based on renewable nitrogen-contained biomass.

Taxonomic identification, phenol biodegradation and soil remediation of the strain Rhodococcus sacchari sp. nov. Z13T

Phenols are highly toxic chemicals that are extensively used in industry and produce large amounts of emissions. Notably, phenols released into the soil are highly persistent, causing long-term harm to human health and the environment. In this study, a gram-positive, aerobic, and rod-shaped bacterial strain, Z13T, with efficient phenol degradation ability, was isolated from the soil of sugarcane fields. Based on the physiological properties and genomic features, strain Z13T is considered as a novel species of the genus Rhodococcus, for which the name Rhodococcus sacchari sp. nov. is proposed. The type strain is Z13T (= CCTCC AB 2022327T = JCM 35797T). This strain can use phenol as its sole carbon source. Z13T was able to completely degrade 1200 mg/L phenol within 20 h; the maximum specific growth rate was μmax = 0.93174 h-1, and the maximum specific degradation rate was qmax = 0.47405 h-1. Based on whole-genome sequencing and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, strain Z13T contains a series of phenol degradation genes, including dmpP, CatA, dmpB, pcaG, and pcaH, and can metabolize aromatic compounds. Moreover, the potential of strain Z13T for soil remediation was investigated by introducing Z13T into simulated phenol-contaminated soil, and the soil microbial diversity was analyzed. The results showed that 100% of the phenol in the soil was removed within 7.5 d. Furthermore, microbial diversity analysis revealed an increase in the relative species richness of Oceanobacillus, Chungangia, and Bacillus.

Competitive mechanism of salt-tolerance/degradation-performance of organic pollutant in bacteria: Na+/H+ antiporters contribute to salt-stress resistance but impact phenol degradation

Phenolic-laden wastewater is typically characterized by its high toxicity and high salinity, imposing serious limits on the application of bioremediation. Although a few halotolerant microorganisms have been reported to degrade phenol, their removal efficiency on high concentrations of phenol remains unsatisfactory. What's more, the deep interaction molecular mechanism of salt-tolerance/phenol-degradation performance has not been clearly revealed. Here, a halotolerant strain Aeribacillus pallidus W-12 employed a meta-pathway to efficiently degrade high concentration of phenol even under high salinity conditions. Investigation of salt-tolerance strategy indicated that four Na+/H+ antiporters, which are widely distributed in bacteria, synergistically endowed the strain with excellent salt adaptability. All these antiporters differentially but positively responded to salinity changes and induction of phenol, forming a synergistic transport effect on salt ions and phenol. In-depth analysis revealed a competitive relationship between salt tolerance and degradation performance, which significantly impaired the degradation efficiency at relatively high salinity. The efficient degradation performance of W-12 under different phenol concentrations and salinity conditions indicated its bioremediation potential for multiple types of phenolic wastewater. Collectively, the competitive mechanism of salt tolerance and degradation performance enlightens a new strategy of introducing or re-constructing Na+/H+ antiporters to further improve bioremediation efficiency of hypersaline organic wastewater.

Sustained degradation of phenol under extreme conditions by polyurethane-based Bacillus sp. ZWB3

Phenol is a serious pollutant to the environment, therefore, it is urgent to find a rapid and effective method for its removal. In this study, Bacillus cereus ZWB3 immobilized on a polyurethane (PUF) carrier was studied. The PUF-ZWB3 required only 20 h for the degradation of 1,500 mg L-1 of phenol, shortened by 8 h than the free bacteria. In addition, the PUF-ZWB3 could increase the degradation concentration of phenol from 1,500 to 2,000 mg L-1, and the complete degradation of 2,000 mg L-1 phenol only used 44 h. In addition, the PUF-ZWB3 showed much higher removal of phenol than the free bacteria at different pH values, salt concentrations, and heavy metal ions. Particularly, the PUF-ZWB3 could still completely remove phenol in a strongly alkaline environment, such as pH 10 and 11. In addition, the removal efficiency of phenol by PUF-ZWB3 was still 100% after 10 cycles. This study showed that the PUF immobilization system had great potential in the field of remediation of organic pollution.

Transmission and retention of antibiotic resistance genes (ARGs) in chicken and sheep manure composting

Transmission of ARGs during composting with different feedstocks (i.e., sheep manure (SM), chicken manure (CM) and mixed manure (MM, SM:CM= 3:1 ratio) was studied by metagenomic sequencing. 53 subtypes of ARGs for 22 types of antibiotics were identified as commonly present in these compost mixes; among them, CM had higher abundance of ARGs, 1.69 times than that in SM, while the whole elimination rate of CM, MM and SM were 55.2%, 54.7% and 42.9%, respectively. More than 50 subtypes of ARGs (with 8.6%, 11.4% and 20.9% abundance in the initial stage in CM, MM and SM composting) were "diehard" ARGs, and their abundance grew significantly to 56.5%, 63.2% and 69.9% at the mature stage. These "diehard" ARGs were transferred from initial hosts of pathogenic and/or probiotic bacteria to final hosts of thermophilic bacteria, by horizontal gene transfer (HGT) via mobile gene elements (MGEs), and became rooted in composting products.

A study of highly efficient phenol biodegradation by a versatile Bacillus cereus ZWB3 on aerobic condition

As one of the organic pollutants in industrial wastewater, phenol seriously threatens the environment and human health. Among various methods, microbial degradation of phenol possesses the advantages of nontoxicity and no secondary pollution. Therefore, search for microbial resources that can efficiently degrade phenol has become an important issue. In this study, a strain that could efficiently degrade phenol was isolated. The strain was identified as Bacillus cereus based on its morphology, physiological and biochemical features and 16S rRNA sequence analysis. The strain can completely degrade phenol up to 1,500 mg/L within 26 h (57.7 mg·L^-1·h^-1), under the optimum conditions, faster compared with the known degrading bacteria. The strain could efficiently remove phenol at a wide range of temperatures (22-37 °C) and pH (7-9), and Mn²⁺ and Zn²⁺ stress. Interestingly, this strain displayed the potential on microthermal environment, which could degrade 1,200 mg/L phenol within 36 h at 22 °C. Further, the strain had capacity that used a variety of aromatic compounds as the sole carbon source for growth. This study shows a useful biodegradation route on the wastewater treatment under high phenol concentration conditions, providing alternatives for environmental remediation.

Improving bioremediation process of petroleum wastewater using biosurfactants producing Stenotrophomonas sp. S1VKR-26 and assessment of phytotoxicity

Primarily, this study aims to evaluate the biosurfactant production capability of Stenotrophomonas sp. S1VKR-26, profiling of its bioremediation ability to remediate petroleum refinery wastewater in a lab-scale bioreactor and assessment of phytotoxicity of bioremediated petroleum wastewater. As a result, strain S1VKR-26 was found to produce 5.15 g L^-1 biosurfactant, CMC of 30 mg L^-1 and reduced the surface tension from 60.3 to 30.5 mN m^-1. Different PAHs like naphthalene (93%), phenanthrene (86%), fluoranthene (92%), and pyrene (98.3%), total petroleum hydrocarbons (72.33%) and phenolic compounds (93.06%) were significantly remediated from the wastewater after the treatment of strain S1VKR-26. Moreover, S1VKR-26 strain treated 1:1 diluted petroleum wastewater have higher germination (100%), vigor (486), and seedling (4.86 cm) compared to untreated wastewater. Therefore, the treatment of petroleum refinery wastewater with strain S1VKR-26 could be more effective in the sense of environmental safety and irrigation for crop production in agriculture.

Comparing transcriptome expression profiles to reveal the mechanisms of salt tolerance and exogenous glycine betaine mitigation in maize seedlings

Salt stress is a common abiotic stress that limits the growth, development and yield of maize (Zea mays L.). To better understand the response of maize to salt stress and the mechanism by which exogenous glycine betaine (GB) alleviates the damaging effects of salt stress, the morphology, physiological and biochemical indexes, and root transcriptome expression profiles of seedlings of salt-sensitive inbred line P138 and salt-tolerant inbred line 8723 were compared under salt stress and GB-alleviated salt stress conditions. The results showed that under salt stress the growth of P138 was significantly inhibited and the vivo ion balance was disrupted, whereas 8723 could prevent salt injury by maintaining a high ratio of K+ to Na+. The addition of a suitable concentration of GB could effectively alleviate the damage caused by salt stress, and the mitigating effect on salt-sensitive inbred line P138 was more obvious than that on 8723. Transcriptome analysis revealed that 219 differentially expressed genes (DEGs) were up-regulated and 153 DEGs were down-regulated in both P138 and 8723 under NaCl treatment, and that 487 DEGs were up-regulated and 942 DEGs were down-regulated in both P138 and 8723 under salt plus exogenous GB treatment. In 8723 the response to salt stress is mainly achieved through stabilizing ion homeostasis, strong signal transduction activation, increasing reactive oxygen scavenging. GB alleviates salt stress in maize mainly by inducing gene expression changes to enhance the ion balance, secondary metabolic level, reactive oxygen scavenging mechanism, signal transduction activation. In addition, the transcription factors involved in the regulation of salt stress response and exogenous GB mitigation mainly belong to the MYB, MYB-related, AP2-EREBP, bHLH, and NAC families. We verified 10 selected up-regulated DEGs by quantitative real-time polymerase chain reaction (qRT-PCR), and the expression results were basically consistent with the transcriptome expression profiles. Our results from this study may provide the theoretical basis for determining maize salt tolerance mechanisms and the mechanism by which GB regulates salt tolerance.