Efficacy of exopolysaccharide in dye-laden wastewater treatment: A comprehensive review.

The discharge of dye-laden wastewater into the water streams causes severe water and soil pollution, which poses a global threat to aquatic ecosystems and humans. A diverse array of microorganisms such as bacteria, fungi, and algae produce exopolysaccharides (EPS) of different compositions and exhibit great bioflocculation potency to sustainably eradicate dyes from water bodies. Nanomodified chemical composites of EPS enable their recyclability during dye-laden wastewater treatment. Nevertheless, the selection of potent EPS-producing strains and physiological parameters of microbial growth and the remediation process could influence the removal efficiency of EPS. This review will intrinsically discuss the fundamental importance of EPS from diverse microbial origins and their nanomodified chemical composites, the mechanisms in EPS-mediated bioremediation of dyes, and the parametric influences on EPS-mediated dye removal through sorption/bioflocculation. This review will pave the way for designing and adopting futuristic green and sustainable EPS-based bioremediation strategies for dye-laden wastewater in situ and ex situ.

Rational management of the plant microbiome for the Second Green Revolution.

The Green Revolution of the mid-20th century transformed agriculture worldwide and has resulted in environmental challenges. A new approach, the Second Green Revolution, seeks to enhance agricultural productivity while minimizing negative environmental impacts. Plant microbiomes play critical roles in plant growth and stress responses, and understanding plant-microbiome interactions is essential for developing sustainable agricultural practices that meet food security and safety challenges, which are among the United Nations Sustainable Development Goals. This review provides a comprehensive exploration of key deterministic processes crucial for developing microbiome management strategies, including the host effect, the facilitator effect, and microbe-microbe interactions. A hierarchical framework for plant microbiome modulation is proposed to bridge the gap between basic research and agricultural applications. This framework emphasizes three levels of modulation: single-strain, synthetic community, and in situ microbiome modulation. Overall, rational management of plant microbiomes has wide-ranging applications in agriculture and can potentially be a core technology for the Second Green Revolution.

Dissemination of sulfonamide resistance genes in digester microbiome during anaerobic digestion of food waste leachate.

The preeminence of sulfonamide drug resistance genes in food waste (FW) and the increased utilization of high-strength organic FW in anaerobic digestion (AD) to enhance methane production have raised severe public health concerns in wastewater treatment plants worldwide. In this regard, the dissemination patterns of different sulfonamide resistance genes (sul1 and sul2) and their impact on the digester core microbiota during AD of FW leachate (FWL) were evaluated. The presence of various sulfonamide antibiotics (SAs) in FWL digesters improved the final methane yield by 37 % during AD compared with FWL digesters without SAs. Microbial population shifts towards hydrolytic, acidogenic, and acetogenic bacteria in the phyla Actinobacteriota, Bacteroidota, Chloroflexi, Firmicutes, Proteobacteria, and Synergistota occurred due to SA induced substrate digestion and absorption through active transport; butanoate, propanoate, and pyruvate metabolism; glycolysis; gluconeogenesis; the citrate cycle; and pentose phosphate pathway. The initial dominance of Methanosaeta (89-96 %) declined to 47-53 % as AD progressed and shifted towards Methanosarcina (40 %) in digesters with the highest SA concentrations at the end of AD. Dissemination of sul1 depended on class 1 integron gene (intl1)-based horizontal gene transfer to pathogenic members of Chloroflexi, Firmicutes, and Patescibacteria, whereas sul2 was transmitted to Synergistota independent of intl1. Low susceptibility and ability to utilize SAs during methanogenesis shielded methanogenic archaea against selection pressure, thus preventing them from interacting with sul or intl1 genes, thereby minimizing the risk of antibiotic resistance development. The observed emergence of cationic antimicrobial peptide, vancomycin, and ß-lactam resistance in the core microbiota during AD of FWL in the presence of SAs suggests that multidrug resistance caused by bacterial transformation could lead to an increase in the environmental resistome through wastewater sludge treatment.

Integrative biohydrogen- and biomethane-producing bioprocesses for comprehensive production of biohythane.

The production of biohythane, a combination of energy-dense hydrogen and methane, from the anaerobic digestion of low-cost organic wastes has attracted attention as a potential candidate for the transition to a sustainable circular economy. Substantial research has been initiated to upscale the process engineering to establish a hythane-based economy by addressing major challenges associated with the process and product upgrading. This review provides an overview of the feasibility of biohythane production in various anaerobic digestion systems (single-stage, dual-stage) and possible technologies to upgrade biohythane to hydrogen-enriched renewable natural gas. The main goal of this review is to promote research in biohythane production technology by outlining critical needs, including meta-omics and metabolic engineering approaches for the advancements in biohythane production technology.

High-throughput integrated pretreatment strategies to convert high-solid loading microalgae into high-concentration biofuels.

The commercial feasibility of energy-efficient conversion of highly concentrated microalgal suspensions to produce high-titer biofuels is a major bottleneck due to high energy consumption. Herein, high-titer biofuels (bioethanol, higher-alcohols, and biodiesel) were generated from carbohydrate-rich Chlamydomonas mexicana and lipid-rich Chlamydomonas pitschmannii biomass through energy-saving microwave pretreatment, successive fermentation, and transesterification. Microwave pretreatment needed low specific energy (4.2 MJ/kg) for 100 g/L of microalgal suspension. Proposed sustainable integrated pretreatments method achieved unprecedented total conversion efficiency (67%) and highest biomass utilization (87%) of C. pitschmannii (100 g/L) with high yields of bioethanol (0.48 g-ethanol/g-carbohydrates), higher-alcohols (0.44 g-higher-alcohols/g-proteins), and biodiesel (0.90 g-biodiesel/g-lipids). Transmission electron microscopy showed the changes in the microalgal cellular integrity before and after sequential fermentations. Energy-efficient integrated pretreatments enhanced the extraction efficiency and whole utilization of high-concentration microalgae to generate high-titer biofuels with minimum waste production.

Syntrophic metabolism facilitates Methanosarcina-led methanation in the anaerobic digestion of lipidic slaughterhouse waste.

Different inoculum to slaughterhouse waste (SHW) ratios (Ino/SHW) influences the digester performance, substrate utilization, and methane yield through microbial shift and their metabolic syntrophy. Acetoclastic Methanosarcina (68-87%) was dominant in the exponential phase, overpowering the initial abundance of Methanosaeta (86% of methanogens) in the SHW digesters. Positive interactions among acetogenic and acetate-oxidizing species of Clostridium (11%) with Methanosarcina (84% of methanogens) improved the methanogenic activity (292 mL g-1 VSinitial d-1) and final VS utilization (90%) at the highest Ino/SHW loading. In contrast, significant improvement of methane yield (152% higher than the control) at the lowest Ino/SHW loading was attributed to strong syntrophy among Methanosaeta (24% of methanogens) and its exoelectrogenic partners, Bythopirellula (0.52%) and Mariniphaga (0.08%) and the acetogenic Cloacimonas (0.16%) and Longilinea (0.32%). These syntrophic interactions among the core microbiota induced major metabolic activities, including butanoate, glycine, serine and threonine, methane, propanoate, and pyruvate metabolism, and quorum sensing.

Anaerobic co-digester microbiome during food waste valorization reveals Methanosaeta mediated methanogenesis with improved carbohydrate and lipid metabolism.

This study determines the optimum food waste (FW) loading in an anaerobic digester for methane production. Interrelation between the degradation mechanism and microbial community composition was assessed through in-depth metabolic pathway analysis and gene quantification. Higher methane production and short lag phase were observed in the FW reactors with low substrate loadings (<4% v/v) while extended lag phase and incomplete substrate utilization were observed in the reactors fed with higher substrates (>6% v/v). The long-chain fatty acids (LCFAs) degradation was influenced by initial FW loading, and up to 99% LCFA degradation occurred at 4% FW reactor. The addition of 8 to 10% FW substrate inhibited methanogenesis due to the accumulation of volatile fatty acids (VFA) and low LCFA degradation. Under optimal conditions of substrate loading, Methanosaeta and Methanosarcina were abundant, indicating their role in methanogenesis and syntrophic acetogenesis, along with enhanced metabolic pathways specific for carbohydrate and lipid metabolism.

Rapid recovery of methane yield in organic overloaded-failed anaerobic digesters through bioaugmentation with acclimatized microbial consortium.

Acidification during anaerobic digestion (AD) due to organic overloading is one of the major reasons for process failures and decreased methane productivity in anaerobic digesters. Process failures can cause the anaerobic digesters to stall completely, prolong the digester recovery period, and inflict an increased operational cost on wastewater treatment plants and adverse impacts on the environment. This study investigated the efficacy of bioaugmentation by using acclimatized microbial consortium (AC) in recovering anaerobic digesters stalled due to acidosis. Overloading of digesters with food waste leachate (FWL) led to the accumulation of volatile fatty acids (11.30 g L-1) and a drop in pH (4.67), which resulted in process failure and a 22-fold decline in cumulative methane production compared to that in the initial phase. In the failure phase, the syntrophic and methanogenic activities of the anaerobic digester microbiota were disrupted by a significant decrease in the abundance of syntrophic populations such as Syntrophomonas, Syntrophorhabdus, Sedimentibacter, and Levilinea, and the phylum Euryarchaeota. Bioaugmentation of the failed digesters by adding AC along with the adjustment of pH resulted in the prompt recovery of methane productivity with a 15.7-fold higher yield than that in unaugmented control. The abundance of syntrophic bacteria Syntrophomonas and phylum Euryarchaeota significantly increased by 29- and 17-fold in the recovered digesters, respectively, which showed significant positive correlations with methane productivity. Methanosarcina and acetoclastic Methanosaeta played a major role in the recovery of the digesters; they were later replaced by hydrogenotrophic Methanoculleus. The increase in the abundance of genes associated with biomethanation contributed to digester recovery, according to the functional annotation of 16S rDNA amplicon data. Thus, bioaugmentation with AC could be a viable solution to recover digesters experiencing process failure due to organic overloading.

Microbial Symbiosis: A Network towards Biomethanation.

Biomethanation through anaerobic digestion (AD) is the most reliable energy harvesting process to achieve waste-to-energy. Microbial communities, including hydrolytic and fermentative bacteria, syntrophic bacteria, and methanogenic archaea, and their interspecies symbioses allow complex metabolisms for the volumetric reduction of organic waste in AD. However, heterogeneity in organic waste induces community shifts in conventional anaerobic digesters treating sewage sludge at wastewater treatment plants globally. Assessing the metabolic roles of individual microbial species in syntrophic communities remains a challenge, but such information has important implications for microbially enhanced energy recovery. This review focuses on the alterations in digester microbiome and intricate interspecies networks during substrate variation, symbiosis among the populations, and their implications for biomethanation to aid stable operation in real-scale digesters.

Pretreatment of polysaccharidic wastes with cellulolytic Aspergillus fumigatus for enhanced production of biohythane in a dual-stage process.

Biological pretreatment of polysaccharidic wastes (PWs) is a cost-effective and environmentally friendly approach to improve the digestibility and utilization of these valuable substrates in dual-stage biohythane production. In order to reduce the prolonged incubation time and loss of carbohydrate during the pretreatment of PWs with Aspergillus fumigatus, a systematic optimization using Taguchi methodology resulted in an unprecedented recovery of soluble carbohydrates (362.84 mg g-1) within 5 days. The disruption and fragmentation of lignocellulosic structures in PWs, and possible saccharification of cellulose and hemicellulose components, increased its digestibility. A dual-stage biohythane production with pretreated PWs showed increased yield (214.13 mL g-1 VSadded), which was 56% higher than the corresponding value with the untreated PWs. This resulted in 47% higher energy recovery as biohythane in pretreated biomass compared to untreated biomass. Optimized fungal pretreatment is, therefore, an effective method to improve the digestibility of PWs and its subsequent conversion to biohythane.

Microbial community acclimatization for enhancement in the methane productivity of anaerobic co-digestion of fats, oil, and grease.

The methane productivity and long chain fatty acids (LCFAs) degradation capability of unacclimatized seed sludge (USS) and acclimatized seed sludge (ASS) at different substrate ratios of fats oil and grease (FOG) and mixed sewage sludge were investigated in this study. Biogas produced in ASS in initial phase of anaerobic digestion had higher methane content (65-76%) than that in USS (26-73%). The degradation of major LCFAs in the ASS was 22-80%, 33-191%, and 7-64% higher for the substrate ratios of 100:10, 100:20, and 100:30, respectively, as compared to the LCFAs' degradation in USS. Microbial acclimatization increased the population of Firmicutes (40%), Bacteroidetes (32%), Synergistetes (10%), and Euryarchaeota (8%) in ASS, which supported the faster rate of LCFAs degradation for its later conversion to methane. The significant abundance of Syntrophomonas and Methanosarcina genera in ASS supported faster generation rate of methane in an obligatory syntrophic relationship.

Interspecies microbial nexus facilitated methanation of polysaccharidic wastes.

Compositional variations in organic wastes influence microbial abundancy and syntrophy during anaerobic digestion (AD), impacting the normal performance of digesters for methanation. Investigation of the microbial dynamics during AD following augmentation with polysaccharidic wastes (PW) revealed the association of effective digester performance and methane yields with the microbial nexus. Dominance of the acidogenic saccharolytic genera, Prevotella, Eubacterium, and Lachnoclostridium, enhanced the utilization of carbohydrates (54%) in PW-augmented digesters. Spearman's rs correlation showed dynamic interspecies interactions among acetogenic syntrophs, and that of iron oxidizers/reducers with acetoclastic and hydrogenotrophic methanogens. Propionate oxidizers in Chloroflexi (i.e., Bellilinea, Levilinea, and Longilinea) exhibited positive associations with acetoclastic methanogens. Increase in the population of acetoclastic methanogens (Methanosaeta, 77% and Methanosarcina, 9%) accelerated the methanogenic activity of PW-augmented digesters by 7 times during the exponential phase, increasing the methane yield (75%) compared to the control. Thus, microbial syntrophy facilitated the effective methanation of PW during AD process.

Biological Conversion of Amino Acids to Higher Alcohols.

'Higher' alcohols, which contain more than two carbons, have a higher boiling point, higher cetane number, and higher energy density than ethanol. Blends of biodiesel and higher alcohols can be used in internal combustion engines as next-generation biofuels without any modification and are minimally corrosive over extensive use. Producing higher alcohols from biomass involves fermenting and metabolizing amino acids. In this review, we describe the pathways and regulatory mechanisms involved in amino acid bioprocessing to produce higher alcohols and the effects of amino acid supplementation as a nitrogen source for higher alcohol production. We also discuss the most recent approaches to improve higher alcohol production via genetic engineering technologies for three microorganisms: Saccharomyces cerevisiae, Clostridium spp., and Escherichia coli.

Low pH treatment of starch industry effluent with bacteria from leaf debris for methane production.

Cornstarch industry generates a huge amount of acidic effluent, that is, 5-11 M3 /Mt grinding, with a high load of chemical oxygen demand, 6000-19000 mg/L. The acidic effluent requires neutralization making the treatment process expensive. Methanogenesis under the acidic environment (pH 5-5.5) can reduce the cost of operation as well as treatment time. This research focuses on the evaluation of the optimum condition of COD reduction and methane generation simultaneously from leaf debris sludge using Box-Behnken model. Three 1 L bioreactors were seeded with 5000-10000 mg/L inoculum and operated at different pH 4.0-7.0 for 72 hr up to 10 cycles. The production of methane was found maximum 2980 ml after treating the wastewater from the starch industry at pH 5.57 and 9612.9 mg biomass load at 62.4 hr. The high reduction rate of around 97% shows there is ample opportunity for further research on low pH treatment of waste along with recovery as methane. PRACTITIONER POINTS: The low pH tolerant methanogenic bacteria are promising and are isolable from various natural resources. The low pH tolerant methanogens was able to remove 97% COD from starch industry effluent at pH 5.57. The recovery of methane was 2980 ml from 9612 mg/L COD which is at per with present treatment system thus provides cost effective alternatives.

Acetoclastic methanogenesis led by Methanosarcina in anaerobic co-digestion of fats, oil and grease for enhanced production of methane.

Fats, oil and grease (FOG) are energy-dense wastes that substantially increase biomethane recovery. Shifts in the microbial community during anaerobic co-digestion of FOG was assessed to understand relationships between substrate digestion and microbial adaptations. Excessive addition of FOG inhibited the methanogenic activity during initial phase; however, it enhanced the ultimate methane production by 217% compared to the control. The dominance of Proteobacteria was decreased with a simultaneous increase in Firmicutes, Bacteriodetes, Synergistetes and Euryarchaeota during the co-digestion. A significant increase in Syntrophomonas (0.18-11%), Sporanaerobacter (0.14-6%) and Propionispira (0.02-19%) was observed during co-digestion, which substantiated their importance in acetogenesis. Among methanogenic Archaea, the dominance of Methanosaeta (94%) at the beginning of co-digestion was gradually replaced by Methanosarcina (0.52-95%). The absence/relatively low abundance of syntrophic acetate oxidizers and hydrogenotrophic methanogens, and dominance of acetoclastic methanogens suggested that methane generation during co-digestion of FOG was predominantly conducted through acetoclastic pathway led by Methanosarcina.

Posterior interosseous neuropathy: the diagnostic benefits of a multimodal approach to investigation.

Posterior interosseous neuropathy should be considered in patients presenting with finger and wrist drop and no sensory deficit. Clinical and electrophysiological assessments are key to a diagnosis. MRI may disclose etiological information not available to clinical or neurophysiological assessment, and should be thought as a complementary diagnostic tool.

The short- and medium-term effectiveness of CT-guided selective cervical nerve root injection for pain and disability.

INTRODUCTION: CT-guided cervical nerve root injection with corticosteroid and/or local anesthetic is a recognized technique in the evaluation and treatment of cervical radiculopathy. There are few prospective studies on the efficacy of the various techniques employed in cervical nerve root injection. We present our results from a 1-year prospective series using a CT-guided anterolateral transforaminal approach for cervical nerve root injection of bupivacaine and dexamethasone. METHODS: Pain using a numeric rating scale was assessed at pre-injection, 15 min post-injection, 1 month, and 3 months. Disability was assessed using the Oswestry Neck Disability Index (NDI) questionnaire at pre-injection, 1 month post-injection, and 3 months. RESULTS: In total, 50 patients were followed for 3 months. The mean reductions in pain were: 15 min (77 %), 1 month (39 %), and 3 months (33 %). The mean reductions in NDI were: 1 month (26 %) and 3 months (also 26 %). Results were statistically significant. CONCLUSIONS: CT-guided selective cervical nerve root injection in the treatment of cervical radicular pain and related disability produces statistically significant reductions in pain and disability to at least 3 months post-procedure.

Ultrasound guided Core Biopsy, Fine Needle Aspiration Cytology and Surgical Excision Biopsy in the diagnosis of metastatic squamous cell carcinoma in the head and neck: an eleven year experience.

INTRODUCTION: This study aims to review our 11 year experience of diagnosing metastatic squamous cell carcinoma presenting as head and neck lumps. The techniques of Ultrasound guided Core Biopsy (USCB), Fine Needle Aspiration Cytology (FNAC) and Surgical Excision Biopsy (SEB) are compared. MATERIALS AND METHODS: All patients with metastatic squamous cell carcinoma (SCC) involving the lymph nodes of the head and neck or parotid gland, diagnosed at Eastbourne District General Hospital between January 1998 and November 2009 were identified. The following data items were collated: biopsy location (e.g. cervical lymph node or parotid), any history of likely primary SCC and site, type of biopsy used to establish a conclusive diagnosis (index diagnostic technique), previous biopsies, the technique and their results, subsequent histology results. RESULTS: A total of 90 patients were diagnosed with metastatic squamous cell carcinoma. The index diagnostic technique was USCB in 48 patients, FNAC in 29 and SEB in 13. In 72 (80%) patients the index biopsy was the sole tissue sample taken prior to surgery or other treatment. The remaining 18 patients underwent a total of 22 previous biopsies prior to the index biopsy. 95% (21/22) of these previous biopsies were non-definitive FNAC and 5% (1/22) was a non-definitive USCB. FNACs also demonstrated the highest non-diagnostic rate (42%). The accuracy of USCB and FNAC in correlating with final histopathology was 97% and 85% respectively. CONCLUSIONS: USCB demonstrates excellent results in the diagnosis of metastatic SCC in the head and neck with higher accuracy and greater reliability than FNAC.