Carbon Source Utilization Research Articles

Application of the Biolog EcoPlate™ technique for assessing the microbial metabolic diversity in moss profiles of continental Antarctica

Little is known about metabolic capabilities of microbial assemblages in continental Antarctic to utilize diverse carbon sources within moss profiles consisting of live, senescent, and dead moss tissues in different stages of decomposition. In the present study, microbial metabolic diversity was determined using Biolog EcoPlate™ for samples of Bryum pseudotriquetrum/B. archangelicum complex collected at five sites located in coastal outcrops of the Lützow-Holm Bay area (Queen Maud Land), East continental Antarctica, and effects of chemical, biological, and physical properties of the moss tissues were explored. The average well-color development, the number of substrates utilized, Simpson's diversity index and equitability of the microbial substrate utilization, and the utilization of carbohydrates, amino acids/amines, carboxylic acids, and polymers varied significantly among the five sites and among four layers of moss profiles. Principal component analysis showed that the utilization of L-asparagine, L-arginine, D-galacturonic acid, Tween 40, Tween 80, and D-mannitol mainly contributed to the variance in the microbial metabolic diversity between sites and moss profiles. The linear mixed models indicated that the relative content of recalcitrant organic components, the number of fungal species, and the water content of moss tissues affected the diversity of microbial utilization of carbon sources.

Ultrasound stimulated production of exopolysaccharide with anti-UV radiation activity by increasing cell permeability of Paenibacillus polymyxa

Exopolysaccharide (EPS) produced by Paenibacillus polymyxa PYQ1 may be a promising agent used in the cosmetic field for skin care because of its protective benefits against short-wave ultraviolet (UVC, 100–280 nm) radiation, which induces cytotoxicity in HaCaT cells. We attempted to use low-intensity ultrasound to enhance its fermentation, and the yield of EPS increased by 24 % under the optimum ultrasonic treatment (90 W, 45 s in 9 h). Results of further experiments show that low-intensity ultrasound will kill a few bacterial cells. Therefore, the remaining bacterial cells have more space and more nutrients, growing faster and producing EPS more efficiently. The recoverable physical damage caused by ultrasound increased the cell permeability, and for the first time, we found that low-intensity ultrasound up-regulated the expression of membrane transporters involved with the transport of sucrose and polysaccharides. Owing to these changes, the utilization of carbon sources was accelerated, and the transport of EPS was promoted to the outside of bacterial cells such that the production of EPS was enhanced.

Biogeographic patterns in populations of marine Pseudoalteromonas atlantica isolates.

Intra-specific genomic diversity is well documented in microbes. The question, however, remains whether natural selection or neutral evolution is the major contributor to this diversity. We undertook this study to estimate genomic diversity in Pseudoalteromonas atlantica populations and whether the diversity, if present, could be attributed to environmental factors or distance effects. We isolated and sequenced twenty-three strains of P. atlantica from three geographically distant deep marine basins and performed comparative genomic analyses to study the genomic diversity of populations among these basins. Average nucleotide identity followed a strictly geographical pattern. In two out of three locations, the strains within the location exhibited>99.5% identity, whereas, among locations, the strains showed<98.11% identity. Phylogenetic and pan-genome analysis also reflected the biogeographical separation of the strains. Strains from the same location shared many accessory genes and clustered closely on the phylogenetic tree. Phenotypic diversity between populations was studied in ten out of twenty-three strains testing carbon and nitrogen source utilization and osmotolerance. A genetic basis for phenotypic diversity could be established in most cases but was apparently not influenced by local environmental conditions. Our study suggests that neutral evolution may have a substantial role in the biodiversity of P. atlantica.

Evaluation of Laminaria Digitata Hydrolysate for the Production of Bioethanol and Butanol by Fermentation

Seaweeds (macroalgae) are gaining attention as potential sustainable feedstock for the production of fuels and chemicals. This comparative study focuses on the characterization of the microbial production of alcohols from fermentable carbohydrates in the hydrolysate of the macroalgae Laminaria digitata as raw material. The potential of a hydrolysate as a carbon source for the production of selected alcohols was tested, using three physiologically different fermentative microbes, in two main types of processes. For the production of ethanol, Saccharomyces cerevisiae was used as a benchmark microorganism and compared with the strictly anaerobic thermophile Thermoanaerobacterium strain AK17. For mixed production of acetone/isopropanol, butanol, and ethanol (A/IBE), three strictly anaerobic Clostridium strains were compared. All strains grew well on the hydrolysate, and toxicity constraints were not observed, but fermentation performance and product profiles were shown to be both condition- and strain-specific. S. cerevisiae utilized only glucose for ethanol formation, while strain AK17 utilized glucose, mannitol, and parts of the glucan oligosaccharides. The clostridia strains tested showed different nutrient requirements, and were able to utilize glucan, mannitol, and organic acids in the hydrolysate. The novelty of this study embodies the application of different inoculates for fermenting a common brown seaweed found in the northern Atlantic Ocean. It provides important information on the fermentation properties of different microorganisms and pinpoints the value of carbon source utilization when selecting microbes for efficient bioconversion into biofuel and chemical products of interest.

Metabolic reconstruction of the human pathogen Candida auris: using a cross-species approach for drug target prediction.

Candida auris is an emerging human pathogen, associated with antifungal drug resistance and hospital candidiasis outbreaks. In this work, we present iRV973, the first reconstructed Genome-scale metabolic model (GSMM) for C. auris. The model was manually curated and experimentally validated, being able to accurately predict the specific growth rate of C. auris and the utilization of several sole carbon and nitrogen sources. The model was compared to GSMMs available for other pathogenic Candida species and exploited as a platform for cross-species comparison, aiming the analysis of their metabolic features and the identification of potential new antifungal targets common to the most prevalent pathogenic Candida species. From a metabolic point of view, we were able to identify unique enzymes in C. auris in comparison with other Candida species, which may represent unique metabolic features. Additionally, 50 enzymes were identified as potential drug targets, given their essentiality in conditions mimicking human serum, common to all four different Candida models analysed. These enzymes represent interesting drug targets for antifungal therapy, some are already known targets of antifungal agents used in clinical practice, but other new potential drug targets also stand out without any human homolog or drug association in Candida species.

Avaliação da diversidade morfofisiológica e genotípica de bactérias endofíticas isoladas de arroz (Oryza sativa L.)

ABSTRACT Rice production in Brazil incurs high costs due to the significant use of agrochemicals. Some plant growth-promoting rhizobacteria (PGPR) can be used as alternative to fertilizers and phytosanitary products. Thus, the objective of this study was to characterize endophytic bacteria isolated from roots of rice plants. The isolates were characterized based on colony morphology, antibiotic resistance, carbon sources utilization, enzyme activity (catalase, amylase, protease, cellulase, and lipase), inorganic phosphate solubilization, and the 16S-23S rDNA intergenic region. Morphologically, 68% of the isolates presented a rapid growth rate, 46% presented abundant mucus production, and 77% formed viscous colonies. All isolates were resistant to nalidixic acid and 16% presented resistance to streptomycin. The majority (90%) used monosaccharides and disaccharides in carbon source assays. Most of the isolates (95%) were positive for catalase and 63.6% were positive for amylase, protease, lipase, and cellulase activities. Additionally, 59% of them were able to solubilize phosphate. The mean enzymatic index for amylase, cellulase, and protease was 2.8, 3.5, and 1.7 respectively. The similarity analysis revealed high diversity among the isolates, with similarity indices of 70% (based on morphological characteristics) and 60% (based on the intergenic region 16S-23S rDNA). Considering morphophysiological and genotypic characteristics, three promising isolates should be evaluated in studies under field conditions for the potential development of bioproducts to replace industrially manufactured inputs in rice crops.

New Alkali-tolerant and Halo-tolerant Nocardiopsis Strain B20 from Algerian Saharan Soil: Isolation, Taxonomy, and Antifungal Activity

Abstract A newly characterized actinobacterial strain, designated B20, displayed remarkable tolerance to extreme pH and NaCl conditions, while showcasing a diversity in carbon source utilization. Phylogenetic analysis confirmed its taxonomic assignment within the genus Nocardiopsis. However, several physiological features were found to differentiate B20 from its most closely related Nocardiopsis species. Notably, Nocardiopsis sp. B20 demonstrated potent and selective antifungal activity against various micro-fungi, suggesting its potential as a valuable source for targeted antifungal compounds. Ethyl acetate extract contains a bioactive compound, B20-1, displaying antifungal properties. Chemical revelations indicated the presence of sugars and polycyclic aromatic hydrocarbons (PAHs) in B20-1 compound. The discovery of antifungal PAHs derived from natural sources presents promising opportunity for addressing fungal infections while mitigating environmental concerns and resistance risks associated with synthetic fungicides. However, further research is warranted to evaluate efficacy, assess ecological impacts, and explore potential applications across diverse industries.

Mechanochemical one-pot synthesis of heterostructured pentlandite-carbon composites for the hydrogen evolution reaction.

We have utilized carbon sources as milling additives to enable a direct mechanochemical one-pot synthesis of Fe3Co3Ni3S8/carbon (Pn/C) materials using elemental reaction mixtures. The obtained Pn/C materials are thoroughly characterized and their carbon content could be adjusted up to 50 wt%. In addition to carbon black (CB) as an additive, Pn/C materials were produced using graphite, reduced graphene oxide (rGO), and carbon nanotubes (CNTs), which allows the overall physicochemical properties of materials for energy storage applications to be adjusted. By employing the Pn/C materials as electrocatalysts for the HER in a zero-gap proton exchange membrane (PEM) electrolyzer, we were able to reach a current density of 1 A cm-2 at a cell potential as low as 2.12 V using Pn, which was synthesized with 25 wt% CB. Furthermore, electrolysis at an applied current density of 1 A cm-2 for 100 h displays a stable performance, thus providing a sustainable synthesis procedure for potential future energy storage applications. Herein, we show that catalyst supports play an important role in the overall performance.

Carbon Source Utilisation as a Basis of Variability among Different Ramularia Isolates Collected from Cotton Belt of Odisha, India

The impact of various carbon sources on the growth and sporulation of six different Ramularia isolates was investigated by testing eight different sources of carbon in liquid Richard's medium. The mycelial growth was assessed by determining the dry biomass weight, and there were three replicate flasks for each combination of isolates and carbon source. The study showed that the extent of utilization of different carbon sources varied among the isolates, and the highest mean dry biomass weight was recorded by RGKN1 followed by RGGNPR1. Maltose and sucrose were found to be the best source of carbon supporting highest mycelial growth and sporulation. Starch and lactose supported the least mycelial growth and sporulation. The results clearly established the essentiality of carbon source for metabolic activities of the fungus. The study proved the existence of cultural variability among the Ramularia isolates basing on their carbon utilisation.

Metagenomic study of carbon metabolism in black soil microbial communities under lead-lanthanum stress

Pollution of soil environments with heavy metals (HMs) and rare earth elements (REEs) cannot be ignored. We aimed to determine the effects of lead combined with lanthanum (Pb-La) on microbial community structure, carbon metabolism, and differences in carbon source utilization in black soils using EcoPlates™ and a macrogenomic approach. We found that Pb and La contents and the microbial community structure together influence and shape the response of soil carbon metabolism to Pb-La. Compared with controls, microorganisms under pollution stress preferentially use phenolic and carboxylic acids as growth carbon sources. Under Pb-La stress, the relative abundance of Proteobacteria significantly increased, thereby selectively displacing heavy metal-sensitive phyla, such as Chloroflexi, Acidobacteria, and Thaumarchaeota. Altered functional potential of the microbial carbon cycle manifested as differences in carbon metabolism, methane metabolism, and carbon fixation pathways. Furthermore, an appropriate concentration of La can reduce the environmental toxicity of Pb, whereas a high concentration of La has synergistic toxicity with Pb. These findings have important implications for understanding the impact of HM-REE contamination in microbial communities and the functions associated with carbon metabolism in black soils.

Deciphering the global roles of Cold shock proteins in Listeria monocytogenes nutrient metabolism and stress tolerance.

Listeria monocytogenes (Lm) accounts for serious public health and food safety problems owing to its stress resilience and pathogenicity. Based on their regulatory involvement in global gene expression events, cold-shock domain family proteins (Csps) are crucial in expression of various stress fitness and virulence phenotypes in bacteria. Lm possesses three Csps (CspA, CspB, and CspD) whose regulatory roles in the context of the genetic diversity of this bacterium are not yet fully understood. We examined the impacts of Csps deficiency on Lm nutrient metabolism and stress tolerance using a set of csp deletion mutants generated in different genetic backgrounds. Phenotype microarrays (PM) analysis showed that the absence of Csps in ∆cspABD reduces carbon (C-) source utilization capacity and increases Lm sensitivity to osmotic, pH, various chemical, and antimicrobial stress conditions. Single and double csp deletion mutants in different Lm genetic backgrounds were used to further dissect the roles of individual Csps in these phenotypes. Selected PM-based observations were further corroborated through targeted phenotypic assays, confirming that Csps are crucial in Lm for optimal utilization of various C-sources including rhamnose and glucose as well as tolerance against NaCl, β-phenyethylamine (PEA), and food relevant detergent stress conditions. Strain and genetic lineage background-based differences, division of labour, epistasis, and functional redundancies among the Csps were uncovered with respect to their roles in various processes including C-source utilization, cold, and PEA stress resistance. Finally, targeted transcriptome analysis was performed, revealing the activation of csp gene expression under defined stress conditions and the impact of Csps on expression regulation of selected rhamnose utilization genes. Overall, our study shows that Csps play important roles in nutrient utilization and stress responses in Lm strains, contributing to traits that are central to the public health and food safety impacts of this pathogen.

Contribution of Uncharacterized Target Genes of MxtR/ErdR to Carbon Source Utilization by Pseudomonas putida KT2440.

MxtR/ErdR is a two-component system that has been previously described as a regulator of the utilization of acetate in Vibrio cholerae and in some Pseudomonas species. Regulation is achieved by controlling the expression of the acs gene (acetyl-coenzyme A [CoA] synthetase). However, the physiological significance of other identified target genes is not fully understood. Here, we investigated the role of pp_0154 (scpC) and pp_0354/pp_0353 in the soil bacterium Pseudomonas putida KT2440. To this end, the genes were individually deleted and complemented in trans. Then, the growth of the resulting strains on different carbon sources was analyzed. To obtain information on protein function, a bioinformatic analysis was performed, and ScpC was purified and characterized in vitro. Our results indicated that scpC is important for P. putida KT2440 to cope with high concentrations of acetate. The encoded enzyme catalyzes the transfer of coenzyme A between acetate and succinate. On the contrary, pp_0353 and pp_0354 proved to be unimportant for the growth of the strain on acetate under our conditions. Extending the phenotypic analysis to other carbon sources led to the discovery that mxtR, erdR, and pp_0353 are important for the utilization of pyruvate as a carbon source. Taken together, the findings of this study expand the knowledge about the role of the MxtR/ErdR two-component system in carbon source utilization and about the specific functions of its target genes. IMPORTANCE MxtR/ErdR and homologous two-component systems play important roles in the regulatory networks that control cell metabolism and influence bacterial-host interactions. Using the MxtR/ErdR two-component system of the plant growth-promoting soil bacterium Pseudomonas putida KT2440 as a model, this work elucidates the function of previously uncharacterized target genes of MxtR/ErdR and extends the knowledge of the physiological significance of the two-component system. Our results suggest that the target gene scpC encodes an acetate:succinate CoA transferase that is involved in the detoxification of acetate when it is present in large amounts. Furthermore, it is shown that MxtR/ErdR controls the metabolism of not only acetate but also pyruvate. This control involves the target gene pp_0353 (putative exonuclease). These findings may facilitate the optimization of P. putida KT2440 as a chassis for biotechnological applications and may contribute to a better understanding of the regulatory network of pathogens like Pseudomonas aeruginosa.

Milk fermentation by monocultures or co-cultures of Streptococcus thermophilus strains.

Direct vat-set starter cultures are the key ingredient for the production of fermented dairy products. The characteristics of the strains used for fermentation determine the fermentation time, texture and flavor of the fermented milk products. In this study, a large-scale analysis of the acid production rate, texture, carbon source utilization characteristics of Streptococcus thermophilus strains was conducted. All 100 S. thermophilus strains were divided into six groups according to the acid production rate and into two groups according to the consistency texture. A universal medium, basing on the carbon sources metabolic properties were optimized (0.5% lactose and 3.5% glucose), to culture all of the tested strains. Among them 40 strains were used to test pH-controlled conditions using this universal culture medium. After 5-7h of fermentation, the optical density (OD) values of all fermented products exceeded 10, suggesting the potential for high-density cultivation of S. thermophilus. Although the OD could be further increased by adding more glucose, this may have hindered subsequent lyophilization because of high residual lactic acid in the fermented product. Next, the application of Streptococcus thermophilus strains in fermented milk was studied. Monocultures and co-cultures of strains were evaluated and compared. The results revealed the existence of symbiotic or competitive relationships between different S. thermophilus strains. Based on the findings, the mixing ratio of three symbiotic S. thermophilus strains was optimized. A co-culture of these three strains yielded fermented milk with high viscosity, low post-acidification, good sensory properties and processability.

In-situ sludge reduction based on Mn2+-catalytic ozonation conditioning: Feasibility study and microbial mechanisms

To improve the sludge conditioning efficiency without increasing the ozone dose, an in-situ sludge reduction process based on Mn2+-catalytic ozonation conditioning was proposed. Using ozone conditioning alone as a control, a lab-scale sequencing batch reactor coupled with ozonated sludge recycle was evaluated for its operating performance at an ozone dose of 75 mg O3/g VSS and 1.5 mmol/L Mn2+ addition. The results showed a 39.4% reduction in MLSS and an observed sludge yield of 0.236 kg MLSS/kg COD for the O3+Mn2+ group compared to the O3 group (15.3% and 0.292 kg MLSS/kg COD), accompanied by better COD, NH4+-N, TN and TP removal, improved effluent SS and limited impact on excess sludge properties. Subsequently, activity tests, BIOLOG ECO microplates and 16S rRNA sequencing were applied to elucidate the changing mechanisms of Mn2+-catalytic ozonation related to microbial action: (1) Dehydrogenase activity reached a higher peak. (2) Microbial utilization of total carbon sources had an elevated effect, up to approximately 18%, and metabolic levels of six carbon sources were also increased, especially for sugars and amino acids most pronounced. (3) The abundance of Defluviicoccus under the phylum Proteobacteria was enhanced to 12.0% and dominated in the sludge, they had strong hydrolytic activity and metabolic capacity. Denitrifying bacteria of the genus Ferruginibacter also showed an abundance of 7.6%, they contributed to the solubilization and reduction of sludge biomass. These results could guide researchers to further reduce ozonation conditioning costs, improve sludge management and provide theoretical support.

Community Level Physiological Profiling of Microbial Communities Influencing Mine Spoil Genesis in Chronosequence Coal Mine Overburden Spoil

Ecological restoration through mine spoil genesis should be dogmatic and the strategies involved a holistic approach, which emphasizes the role of microbial community composition that varies in accordance with the physiological and nutritional status of mine spoil profiles. This is because the patterns observed aboveground is being driven by the belowground diversity and processes. Thus, the relationship between microbial community structure and mine spoil genesis in chronosequence coal mine spoil has attracted considerable research attention. The occurrence of higher microbial diversity and difficulties in culturing microbes necessitate the use of a culture-independent approach through community-level physiological profiling based on the patterns of carbon source utilization using BIOLOG Ecoplate and thereby the functional diversity of microbial communities in different age series coal mine spoil was determined. The average well-color development exhibited an increasing trend with a minimum in OB0 (0.0640) and a maximum in OB15 (0.5060) over time. The patterns of substrate utilization (carbohydrates, carboxylic and ketonic acids, amino acids, polymers, amines, and amides) reflect the shift in microbial community composition in different age series coal mine spoil over time. Gradual increase in species richness and Shannon diversity index with the increase in age of mine spoil substantiated relatively higher microbial diversity reflecting the sign of mine spoil genesis. Principal component analysis and redundancy analysis based on the differential patterns of substrate utilization discriminate different age series coal mine spoil into independent clusters, which evaluated the broad-scale patterns of microbial community dynamics influencing the pace and progress of mine spoil genesis.

Systematic analysis of Baobaoqu fermentation starter for Wuliangye Baijiu by the combination of metagenomics and metabolomics.

Baobaoqu (BBQ) is a traditional fermenting power, which is widely applied in Nong-flavor Baijiu brewing. There are two different types of BBQ (premium BBQ and normal BBQ) used in industrial manufacture, but the reasons for the significant differences between two kinds of BBQ have not been clearly illuminated. In this study, the combination of metagenomics and metabolomics was performed to compare the differences in the composition of microbial communities and the components of flavors between premium BBQ and normal BBQ. The results showed that the glycosidase-producing microorganisms are the biomarkers of premium BBQ, contributing a better ability of carbon source utilization than normal BBQ. In addition, several important flavors (ethyl hexanoate, phenylethanol, ethyl acetate) were rich in normal BBQ, which have a significant positive correlation with the biomarkers (Lactobacillus and Pichia kudriavzevii) of normal BBQ. It suggests that the microbial community has an advantage in utilizing raw materials in premium BBQ, while the community was inclined to form flavors in normal BBQ. The differences between two types of BBQ at the microbial and flavor level have theoretical and practical guiding significance in the application of premium and normal BBQ and in the further improvements of taste and quality of Baijiu.

VdERG2 was involved in ergosterol biosynthesis, nutritional differentiation and virulence of Verticillium dahliae.

The ergosterol biosynthesis pathway plays an important role in model pathogenic bacteria Saccharomyces cerevisiae, but little is known about the biosynthesis of ergosterol in the pathogenic fungus Verticillium dahliae. In this study, we identified the VdERG2 gene encoding sterol C-8 isomerase from V. dahliae and investigated its function in virulence by generating gene deletion mutants (ΔVdERG2) and complemented mutants (C-ΔVdERG2). Knockout of VdERG2 reduced ergosterol content. The conidial germination rate and conidial yield of ΔVdERG2 significantly decreased and abnormal conidia were produced. In spite of VdERG2 did not affect the utilization of carbon sources by V. dahliae, but the melanin production of ΔVdERG2 was decreased in cellulose and pectin were used as the sole carbon sources. Furthermore, the ΔVdERG2 mutants produced less microsclerotia and melanin with a significant decrease in the expression of microsclerotia and melanin-related genes VaflM, Vayg1, VDH1, VdLAC, VdSCD and VT4HR. In addition, mutants ΔVdERG2 were very sensitive to congo red (CR), sodium dodecyl sulfate (SDS) and hydrogen peroxide (H2O2) stresses, indicating that VdERG2 was involved in the cell wall and oxidative stress response. The absence of VdERG2 weakened the penetration ability of mycelium on cellophane and affected the growth of mycelium. Although ΔVdERG2 could infect cotton, its pathogenicity was significantly impaired. These phenotypic defects in ΔVdERG2 could be complemented by the reintroduction of a full-length VdERG2 gene. In summary, as a single conservative secretory protein, VdERG2 played a crucial role in ergosterol biosynthesis, nutritional differentiation and virulence in V. dahliae.

Carbon source utilization pattern of soil bacterial microbiome of bambara groundnut rhizosphere at the different growth stages determines soil fertility

The diversity of microbes in the soil of plants is important for sustainable agriculture as these microbes are important in carrying out different functional processes to improve the soil and invariably plant growth. Inversely the presence of the crop also affects the types of microbial communities in the soil. In this study, bambara groundnut was grown during the planting season in South Africa, from November to March 2014/2015 and 2015/2016 and soil samples were taken after every 4 weeks after planting. Soil samples were taken 15 cm deep from 2 different landraces named VBR and VL. Microbial diversity was determined by soil microbial Carbon Source Utilization Profiles (CSUP) using BIOLOG™ GN2 plates. The abundance and richness of the soil microbes was also determined using the Shannon-Weaver and Evenness diversity indices. The diversity of the soil microbial population changed over the stages of plant growth, according to cluster analysis. Bacterial abundance and diversity were higher at 4 and 8 weeks after planting (WAP). The microbial abundance (richness index) in this study ranged from 0.64 to 0.94 with cultivar VL2 at 8 WAP being the highest while bulk soil (control), R2 was the lowest. The Shannon-Weaver index varied between 2.19 and 4.00 with the lowest corresponding to control while the highest was VL2 at 8 WAP. Carbon sources utilized by bacterial communities spread across the 96 carbon sources. The highest utilization of carboxylic acids, ester, amino acids and polymers and carbohydrates was found in the bacterial communities of the different landraces across growth stages. The highest utilization of alcohols, amides, amines, aromatic chemicals, brominated chemicals and phosphorylated chemicals was found in the control landraces. This indicates that the soil samples between 4 WAP and 12 WAP were richer in diversity of microbial species and their abundance. This soil diversity and richness is an indicator of the quality of the soil in order to increase crop yields and agricultural production.

Insight into Na+ assistant anaerobic fermentation of waste activated sludge from carbon migration, bio-transformation and recovery perspectives

Short-chain fatty acids (SCFAs) produced from anaerobic fermentation of waste activated sludge (WAS) have been regarded as the preferred carbon source, however the carbon migration pattern has rarely been reported. This work elucidated that the Na+ assistant anaerobic fermentation could facilitate carbon source release and bio-transformation towards carbon recovery from WAS. Obvious disintegration of sludge flocs and property variation of solid–liquid interface were triggered with Na+-regulation, leading to extracellular polymeric substance disruption and microbial cell apoptosis by protein structure loosening and osmotic pressure stress. Thereby, extracellular and intracellular carbon source (e.g. proteins, carbohydrates) were simultaneously solubilized, contributing to considerable carbon migration from sludge solid into liquid phase (up to 20.43 %). Meanwhile, 61.30 % of the released carbon source was bio-transformed with the improved sludge acidification in 4-day Na+ assistant anaerobic fermentation. Substantial SCFAs of 61.39 mg C/g VSS was produced, which was mainly composed by acetate and propionate (69.07 %). As such, the overall carbon recovery rate of 12.51 % was achievable. The carbon source bio-availability in fermentative liquid indeed created economic benefits and carbon-emission reduction depending on alternative carbon source utilization and residual carbon source reduction in fermented sludge disposal.

Identification of Fungal Communities Isolated from Himalayan Glacier Cryoconites

The current study focuses on fungi that were isolated from cryoconite holes of the Hamtah glacier in the Himalayas. Cryoconite holes have ecological and biotechnological importance. A total of seven cryoconite samples were collected from different locations and subjected to the isolation of psychotropic fungi at 1, 4, 15 and 22 °C. Isolates were identified by ITS and D1/D2 region sequences. The result showed culturable yeasts (45) and filamentous fungi (10) belonging to four ascomycetous classes (Dothideomycetes, Eurotiomycetes, Saccharomycetes and Sordariomycetes) and two basidiomycetes’ classes (Microbotryomycetes and Tremellomycetes). Physiological characteristics such as the pH, temperature, salt tolerance, carbon source utilization and antibiotics sensitivity of the isolates were studied. All the isolates were grown from acidic to alkaline pH and were able to grow at 1 to 22 °C. The fungal cultures isolated were screened to produce cold active enzymes such as amylase, cellulase, lipase, protease and catalase. Cellulase activity was detected at its maximum at both 4 and 15 °C. Himalayan cryoconites fungi showed immense potential for biotechnological and industrial applications. To the best of our knowledge, this is the first record of the characterization of fungal communities present in the glacier cryoconites of the Himalayas.