Biotransformation of phenolic compounds by Bacillus aryabhattai

Under explored roles of microbial ligninolytic enzymes in aerobic polychlorinated biphenyl transformation

Polychlorinated biphenyls (PCBs) are persistent organic pollutants in the environment that are responsible for many adverse health effects. Bioremediation appears to be a healthy and cost-effective alternative for remediating PCB-contaminated environments. While some microbial species have been observed to be capable of transforming PCBs, only two different microbial pathways (rdh and bph pathways) have been described to be involved in PCB transformations. Ligninolytic enzymes have been observed or are under suspicion in some microbial PCB transformations. However, the role of these promising PCB-transforming enzymes, which are produced by fungi and some aerobic bacteria, is still unclear. The present review describes their role by identifying microbial PCB-transforming species and their reported ligninolytic enzymes whether proven or suspected to be involved in PCB transformations. There are several lines of evidence that ligninolytic enzymes are responsible for PCB transformations such as (1) the ability of purified laccases from Myceliophthora thermophila, Pycnoporus cinnabarinus, Trametes versicolor, Cladosporium sp, and Coprinus cumatus to transform hydroxy-PCBs; (2) the increased production of laccases and peroxidases by many fungi in the presence of PCBs; and (3) the enhanced PCB transformation by Pseudomonas stutzeri and Sinorhizobium meliloti NM after the addition of ligninolytic enzyme enhancers. However, if the involvement of ligninolytic enzymes in PCB transformation is clearly demonstrated in some fungal species, it does not seem to be implicated in all microbial species suggesting other still unknown metabolic pathways involved in PCB transformation and different from the bph and rdh pathways. Therefore, PCB transformation may involve several metabolic pathways, some involving ligninolytic enzymes, bph or rdh genes, and some still unknown, depending on the microbial species. In addition, current knowledge does not fully clarify the role of ligninolytic enzymes in PCB oxidation and dechlorination. Therefore, further studies focusing on purified ligninolytic enzymes are needed to clearly elucidate their role in PCB transformation.

Effects of microbial agent and microbial fertilizer input on soil microbial community structure and diversity in a peanut continuous cropping system

INTRODUCTION

The soil harbors a diverse array of microorganisms, and these are essential components of terrestrial ecosystems. The presence of microorganisms in the soil, particularly in the rhizosphere, is closely linked to plant growth and soil fertility.

OBJECTIVE

The primary objective of this study is to assess the potential advantages of integrating microbial inoculants with compound fertilizer in enhancing peanut yield.

METHODS

We utilized Illumina MiSeq high-throughput sequencing technology to conduct our investigation. The experimental design consists of four treatment groups: compound fertilizers (CF), compound fertilizers supplemented with microbial agents (CF + MA), compound fertilizers supplemented with microbial fertilizers (CF + MF), and compound fertilizers supplemented with both microbial agents and microbial fertilizers (CF + MM).

RESULTS

The experimental results demonstrated a significant increase in peanut yield upon application of CF + MA, CF + MF, and CF + MM treatments. During the blossom stage and pod-setting stage, the soil's catalase, urease, and acid phosphatase activities were significantly increased in the CF + MA, and CF + MM treatments compared to the CF treatment. The application of CF + MA resulted in an increase in bacterial richness in the rhizosphere soil of peanuts, as indicated by the sequencing results. The application of CF + MA, CF + MF, and CF + MM resulted in a reduction of fungal diversity. Proteobacteria, Actinobacteria, and Acidobacteria were the dominant bacterial phyla, while Ascomycota and Basidiomycota were the dominant phyla in the fungal component of the rhizosphere soil microbiome across all experimental treatments.

CONCLUSION

Microbial agents and fertilizers modify the peanut rhizosphere soil's microbial community structure, as per our findings. The abundance of potentially beneficial bacteria (Bradyrhizobium, Rhizobium, and Burkholderia) and fungi (Trichoderma and Cladophialophora) could increase, while pathogenic fungi (Penicillium and Fusarium) decreased, thereby significantly promoting plant growth and yield of peanut.

Deciphering ligninolytic enzymes in the secretome of Pycnoporus sp. and their potential in degradation of 2-chlorophenol

Chlorophenols and their derivatives are persistent environmental pollutants, posing a threat to terrestrial and aquatic life. The biological approach for eliminating toxic contaminants is an effective, sustainable, and environmental friendly method. In this study, the crude enzymes present in the secretome of white-rot fungus (Pycnoporus sp.) were explored for the degradation of 2-chlorophenol. The activity of ligninolytic enzymes in the secretome was analyzed and characterized for their kinetics and thermodynamic properties. Laccase and manganese peroxidase were prevalent ligninolytic enzymes and exhibited temperature stability in the range of 50-65 °C and pH 4-5, respectively. The kinetic parameters Michaelis constant (Km) and turnover number (Kcat) for Lac were 42.54 μM and 45 s-1 for 2,2'-azino-bis (3-ethylben- zothiazoline-6-sulfonic acid), and 93.56 μM and 48 s-1 towards 2,6-dimethoxyphenol whereas Km and Kcat for MnP were 2039 μM and 294 s-1 for guaiacol as substrate. Treatment with the crude enzymes laccase and manganese peroxidase results in the reduction of 2-chlorophenol concentration, confirmed by UV-visible absorption spectra and high-performance liquid chromatography analysis. The detoxification of 2-chlorophenol into less toxic forms was confirmed by the plate toxicity assay. This study demonstrated that crude enzymes produced by Pycnoporus sp. could potentially minimize the toxicity of phenolic compounds in a sustainable way.

Screening of antibacterial activities of Bacillus spp. isolated from the Parangkusumo coastal sand dunes, Indonesia

Background: The emergence of multidrug-resistant bacteria because of poor understanding of the issue and the misuse of antibiotics has become global health concern. Therefore, the discovery of novel antibacterial drugs is urgently needed. New antibacterial compounds may be found in the Bacillus species, which are abundant in sand dune ecosystems. Herein, we examined samples from the Parangkusumo coastal sand dunes in Indonesia.Methods: Samples were collected from three areas in the sand dunes (the area closest to the sea, the core area of sand dunes, and the area farthest from the sea). The samples were inoculated on Luria Bertani agar. Morphological and molecular identification was performed on the basis of 16S rRNA. The samples’ antimicrobial activity was evaluated with the disc diffusion method and compared with that of opportunistic pathogenic bacteria.Results: Five species of Bacillus were successfully isolated from the Parangkusumo coastal sand dunes. To our knowledge, this is the first report of the isolation of Bacillus aryabhattai in Indonesia. All samples showed antimicrobial activity against pathogenic bacteria. B. velezensis and B. subtilis showed antibacterial activity against Gram-positive bacteria, whereas B. aryabhattai and B. megaterium showed antibacterial activity against Gram-negative bacteria, and B. spizizenii showed antibacterial activity toward Gram-positive and Gram-negative bacteria.Conclusion: Five Bacillus species were successfully isolated from the Parangkusumo coastal sand dunes, Indonesia, and all samples showed antimicrobial activity toward opportunistic pathogenic bacteria. The crude antimicrobial compounds from B. megaterium, B. aryabhattai, B. subtilis, and B. spizizenii showed the highest growth-inhibition activity against E. coli, P. aeruginosa, B. cereus, and S. aureus, respectively.

Bioremediation of lignin derivatives and phenolics in wastewater with lignin modifying enzymes: Status, opportunities and challenges

Lignin modifying enzymes from fungi and bacteria are potential biocatalysts for sustainable mitigation of different potentially toxic pollutants in wastewater. Notably, the paper and pulp industry generates enormous amounts of wastewater containing high amounts of complex lignin-derived chlorinated phenolics and sulfonated pollutants. The presence of these compounds in wastewater is a critical issue from environmental and toxicological perspectives. Some chloro-phenols are harmful to the environment and human health, as they exert carcinogenic, mutagenic, cytotoxic, and endocrine-disrupting effects. In order to address these most urgent concerns, the use of oxidative lignin modifying enzymes for bioremediation has come into focus. These enzymes catalyze modification of phenolic and non-phenolic lignin-derived substances, and include laccase and a range of peroxidases, specifically lignin peroxidase (LiP), manganese peroxidase (MnP), versatile peroxidase (VP), and dye-decolorizing peroxidase (DyP). In this review, we explore the key pollutant-generating steps in paper and pulp processing, summarize the most recently reported toxicological effects of industrial lignin-derived phenolic compounds, especially chlorinated phenolic pollutants, and outline bioremediation approaches for pollutant mitigation in wastewater from this industry, emphasizing the oxidative catalytic potential of oxidative lignin modifying enzymes in this regard. We highlight other emerging biotechnical approaches, including phytobioremediation, bioaugmentation, Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-based technology, protein engineering, and degradation pathways prediction, that are currently gathering momentum for the mitigation of wastewater pollutants. Finally, we address current research needs and options for maximizing sustainable biobased and biocatalytic degradation of toxic industrial wastewater pollutants.

Streptomyces tunisiensis DSM 42037 mediated bioconversion of ferulic acid released from barley bran

Streptomyces tunisiensis DSM 42037 exhibited growth capacity on a minimum medium containing 1% barley bran. This peculiar strain released 83.5% of total ferulic acid present in barley bran after 5 days of incubation and the highest amount of released ferulic acid (19 mg/L) was observed on the 3rd day of incubation. The concentrated supernatant of S. tunisiensis also released ferulic acid from the parietal arabinoxylan complex of barley bran. This strain was able to convert the free ferulic acid into 4-vinyl guaiacol (14 mg/L) and acetovanillone (12 mg/L) at molar yield of 97% and 83% respectively. The biotransformation products were successively purified by preparative thin layer and silica gel column chromatography followed by HPLC and identified by ¹H nuclear magnetic resonance. Streptomyces tunisiensis DSM 42037 could have potential applications in the food, pharmaceutical and cosmetic industries thanks to its ability in biotransforming ferulic acid into 4-vinyl guaiacol and acetovanillone.

Feeding strategies to optimize vanillin production by Amycolatopsis sp. ATCC 39116

The growing consumer demand for natural products led to an increasing interest in vanillin production by biotechnological routes. In this work, the biotechnological vanillin production by Amycolatopsis sp. ATCC 39116 is studied using ferulic acid as precursor, aiming to achieve maximized vanillin productivities. During biotech-vanillin production, the effects of glucose, vanillin and ferulic acid concentrations in the broth proved to be relevant for vanillin productivity. Concerning glucose, its presence in the broth during the production phase avoids vanillin conversion to vanillic acid and, consequently, increases vanillin production. To avoid the accumulation of vanillin up to a toxic concentration level, a multiple-pulse-feeding strategy is implemented, with intercalated vanillin removal from the broth and biomass recovery. This strategy turned out fruitful, leading to 0.46 g L^-1 h^-1 volumetric productivity of vanillin of and a production yield of 0.69 g_vanillin g_{ferulic acid}^-1, which are among the highest values reported in the literature for non-modified bacteria.

Composition and biotransformational changes in soluble microbial products (SMPs) along an anaerobic baffled reactor (ABR)

This work examined the production and catabolism/biotransformation dynamics of SMPs down the length of an eight-compartment-anaerobic baffled reactor (ABR) which physically separates the biological processes, in contrast to completely mixed reactors which do not enable these dynamics to measured, and this is totally novel. SMPs were extracted and characterised by gas and liquid chromatography coupled mass spectrometry to determine their composition and production/catabolism. 60%-70% of the feed compounds decreased from the first to fourth compartment; the increase in SMPs after the fourth compartment suggested a mixture of degraded and biotransformed compounds, and microbial products. High concentrations of low MW alkanes and alkenes, and higher MW (up to 2000 Da) lipids and amino acid derivatives accumulate in the last compartment at pseudo-steady state, and past work identifying polysaccharides/peptides as major membrane biofoulants have excluded these lipids. In addition, lipids and changes detected during feed transients have not been noted before in previous work. Finally, feed step-increases also increased some amino acid derivatives used in cell-signalling. Interestingly, some natural products from plant and fungal extracts were also found in the fourth compartment, where methanogenesis was the dominant process.

Strategies for the production of biochemicals in bioenergy crops

Industrial crops are grown to produce goods for manufacturing. Rather than food and feed, they supply raw materials for making biofuels, pharmaceuticals, and specialty chemicals, as well as feedstocks for fabricating fiber, biopolymer, and construction materials. Therefore, such crops offer the potential to reduce our dependency on petrochemicals that currently serve as building blocks for manufacturing the majority of our industrial and consumer products. In this review, we are providing examples of metabolites synthesized in plants that can be used as bio-based platform chemicals for partial replacement of their petroleum-derived counterparts. Plant metabolic engineering approaches aiming at increasing the content of these metabolites in biomass are presented. In particular, we emphasize on recent advances in the manipulation of the shikimate and isoprenoid biosynthetic pathways, both of which being the source of multiple valuable compounds. Implementing and optimizing engineered metabolic pathways for accumulation of coproducts in bioenergy crops may represent a valuable option for enhancing the commercial value of biomass and attaining sustainable lignocellulosic biorefineries.