Synthesis Of Extracellular Enzymes Research Articles

Effects of Acupuncture on Cartilage Degradation and Joint Pain in Osteoarthritis

Osteoarthritis, resulting from joint decline, leads to various symptoms including joint pain, stiffness, tenderness, and local inflammation. These symptoms may be caused by the remodeling of the five structural phenotypes: inflammatory, subchondral bone, meniscal cartilage, atrophic, and hypertrophic phenotypes. Studies have shown that acupuncture can inhibit cartilage degradation by regulating extracellular matrix-degradation and enzyme synthesis. Notably, the efficacy of acupuncture treatment in osteoarthritis may be attributed to regulated inflammation and apoptosis of chondrocytes, as well as endogenous opioid production, and activation of the endocannabinoid systems (in the central and peripheral nervous systems), to contribute towards cartilage protection and joint pain relief. This review provides a current summary of the mechanisms of action of acupuncture in osteoarthritis, indicating that acupuncture, a therapy with fewer side effects than conventional medications, may be an effective treatment strategy for the management of osteoarthritis.

Novel trans-Resveratrol Derivatives: Design, Synthesis, Antibacterial Activity, and Mechanisms.

Rice bacterial leaf blight and rice bacterial leaf streak have induced tremendous damage to production of rice worldwide. To discover an effective novel antibacterial agent, a series of novel trans-resveratrol (RSV) derivatives containing 1,3,4-oxadiazole and amide moieties were designed and synthesized for the first time. Most of them showed excellent antibacterial activities against Xanthomonas oryzae pv oryzicola and Xanthomonas oryzae pv oryzae. Especially, compound J12 had the best inhibitory with the half-maximal effective concentration values of 4.2 and 5.0 mg/L, respectively, which were better than that of RSV (63.7 and 75.4 mg/L), bismerthiazol (79.5 and 89.6 mg/L), and thiodiazole copper (105.4 and 112.8 mg/L). Furthermore, compound J12 had an excellent control effect against rice bacterial leaf streak and rice bacterial leaf blight, with protective activities of 46.2 and 42.1% and curative activities of 44.5 and 41.7%, respectively. Preliminary mechanisms indicated that compound J12 could not only remarkably decrease biofilm formation, extracellular polysaccharide production, and the synthesis of extracellular enzymes but also destroy bacterial cell surface morphology, thereby reducing the pathogenicity of bacteria. In addition, compound J12 could increase the activity of defense-related enzymes and affect the expression of multiple pathogenic-related genes including plant-pathogen interaction, the MAPK signaling pathway, and phenylpropanoid biosynthesis, and this could improve the defense of rice against rice bacterial leaf streak infection. The present work indicates that the RSV derivatives can be used as promising candidates for the development of antibacterial agents.

DegQ is an important policing link between quorum sensing and regulated adaptative traits in Bacillus subtilis.

Quorum sensing (QS) is a widespread bacterial communication system that controls important adaptive traits in a cell density-dependent manner. However, mechanisms by which QS-regulated traits are linked within the cell and mechanisms by which these links affect adaptation are not well understood. In this study, Bacillus subtilis was used as a model bacterium to investigate the link between the ComQXPA QS system, DegQ, surfactin and protease production in planktonic and biofilm cultures. The work tests two alternative hypotheses predicting that hypersensitivity of the QS signal-deficient mutant (comQ::kan) to exogenously added ComX, resulting in increased surfactin production, is linked to an additional genetic locus, or alternatively, to overexpression of the ComX receptor ComP. Results are in agreement with the first hypothesis and show that the P srfAA hypersensitivity of the comQ::kan mutant is linked to a 168 strain-specific mutation in the P degQ region. Hence, the markerless ΔcomQ mutant lacking this mutation is not overresponsive to ComX. Such hyper-responsiveness is specific for the P srfAA and not detected in another ComX-regulated promoter, the P aprE , which is under the positive control by DegQ. Our results suggest that DegQ by exerting differential effect on P srfAA and P aprE acts as a policing mechanism and the intracellular link, which guards the cell from an overinvestment into surfactin production. IMPORTANCE DegQ levels are known to regulate surfactin synthesis and extracellular protease production, and DegQ is under the control of the ComX-dependent QS. DegQ also serves as an important policing link between these QS-regulated processes, preventing overinvestment in these costly processes. This work highlights the importance of DegQ, which acts as the intracellular link between ComX production and the response by regulating extracellular degradative enzyme synthesis and surfactin production.

Enhancement of Growth and Synthesis of Extracellular Enzymes of Morchella sextelata Induced by Co-culturing with Trichoderma.

Trichoderma is a genus of common filamentous fungi that display a various range of lifestyles and interactions with other fungi. The interaction of Trichoderma with Morchella sextelata was explored in this study. Trichoderma sp. T-002 was isolated from a wild fruiting body of Morchella sextelata M-001 and identified as a closely related species of Trichoderma songyi based on morphological chracteristics and phylogenetic analysis of translation elongation factor1-alpha and inter transcribed spacer of rDNA. Further, we focussed on the influence of dry mycelia of T-002 on the growth and synthesis of extracellular enzymes of M-001. Among different treatments, M-001 showed the highest growth of mycelia with an optimal supplement of 0.33g/100mL of T-002. Activities of extracellular enzymes of M-001 were enhanced significantly by the optimal supplement treatment. Overall, T-002, a unique Trichoderma species, had a positive effect on mycelial growth and synthesis of extracellular enzymes of M-001.

Growth Promotion of Guava “Pear” (Psidium guajava cv.) by Sinorhizobium mexicanum in Southern Mexican Agricultural Fields

Biofertilizers formulated with nitrogen-fixing bacteria represent an alternative to chemical fertilizers because they increase soil fertility and protect the environment. Therefore, the objective of this study was to analyze the effects on the growth of guava “pear” (Psidium guajava cv.) after inoculation with a nitrogen fixing bacterium Sinorhizobium mexicanum ITTG-R7T. The study was carried out in an agricultural rural area of Chiapas, Mexico, where farmers do not have programs of regenerative agriculture. First, the agricultural soil was subjected to physicochemical and metagenomic analysis in order to determine the soil quality and its bacterial community composition. Likewise, multifunctional biochemical tests and plant inoculation assays were evaluated to determine the potential of S. mexicanum ITTG-R7T as plant-growth-promoting bacteria (PGPB). The site was rain fed and had silty clay loam soil with abundant Bacillaceae. S. mexicanum ITTG-R7T showed different properties as PGPB such as the production of indole compounds, synthesis of extracellular enzymes, phosphate solubilization, synthesis of siderophores, ACC (1-aminocyclopropane-1-carboxylate) deaminase, and nitrogenase activity (ARA). When the strain ITTG-R7 T was combined with chemical nutrients, it had the highest positive effect on the growth and development of guava plants. Guava biofertilization with ITTG-R7T had a significant influence (p < 0.05) mainly on the total plant height (368.83 cm), number of flowers (36.0) and the amount of chlorophyll (2.81 mg mL−1) in comparison with the other treatments evaluated. ITTG-R7T is a promising strain for improving the guava crop yield.

Global Climate Change Effects on Soil Microbial Biomass Stoichiometry in Alpine Ecosystems

Alpine ecosystems are sensitive to global climate change-factors, which directly or indirectly affect the soil microbial biomass stoichiometry. In this paper, we have compared the soil microbial biomass stoichiometry ratios of alpine ecosystems using the global average values. In the comparison, the responses and mechanisms of soil microbial biomass stoichiometry to nitrogen deposition, altered precipitation, warming, and elevated atmospheric carbon dioxide (CO2) concentration in the alpine ecosystem were considered. The alpine ecosystem has a higher soil microbial-biomass-carbon-to-nitrogen ratio (MBC:MBN) than the global average. In contrast, the soil microbial-biomass-nitrogen-to-phosphorus (MBN:MBP) and carbon-to-phosphorus ratios (MBC:MBP) varied considerably in different types of alpine ecosystems. When compared with the global average values of these ratios, no uniform pattern was found. In response to the increase in nitrogen (N) deposition, on the one hand, microbes will adopt strategies to regulate extracellular enzyme synthesis and excrete excess elements to maintain stoichiometric balance. On the other hand, microbes may also alter their stoichiometry by storing excess N in their bodies to adapt to the increased N in the environment. Thus, a decrease in MBC:MBN and an increase in MBN:MBP are observed. In addition, N deposition directly and indirectly affects the soil fungal-to-bacterial ratio (F:B), which in turn changes the soil microbial biomass stoichiometry. For warming, there is no clear pattern in the response of soil microbial biomass stoichiometry in alpine ecosystems. The results show diverse decreasing, increasing, and unchanging patterns. Under reduced precipitation, microbial communities in alpine ecosystems typically shift to a fungal dominance. The latter community supports a greater carbon-to-nitrogen ratio (C:N) and thus an increased soil MBC:MBN. However, increased precipitation enhances N effectiveness and exacerbates the leaching of dissolved organic carbon (DOC) and phosphorus (P) from alpine ecosystem soils. As a result, a decrease in the soil MBC:MBN and an increase in the soil MBN:MBP are evident. Elevated atmospheric CO2 usually has little effect on the soil MBC:MBN in alpine ecosystems, mainly because of two reasons. These are: (i) N is the main limiting factor in alpine ecosystems, and (ii) alpine ecosystems accumulate higher soil organic carbon (SOC) and microbes and preferentially decompose “old” carbon (C) stocks. The response of soil microbial stoichiometry to global climate change factors in alpine ecosystems is diverse, and the impact pathways are complex. Future studies need to focus on the combined effects of multiple global climate change factors on microbial stoichiometry and the mechanism of microbial stoichiometric balance.

Stress-Tolerant Endophytic Isolate Priestia aryabhattai BPR-9 Modulates Physio-Biochemical Mechanisms in Wheat (Triticum aestivum L.) for Enhanced Salt Tolerance.

In efforts to improve plant productivity and enhance defense mechanisms against biotic and abiotic stresses, endophytic bacteria have been used as an alternative to chemical fertilizers and pesticides. In the current study, 25 endophytic microbes recovered from plant organs of Triticum aestivum L. (wheat) were assessed for biotic (phyto-fungal pathogens) and abiotic (salinity, drought, and heavy metal) stress tolerance. Among the recovered isolates, BPR-9 tolerated maximum salinity (18% NaCl), drought (15% PEG-6000), and heavy metals (µg mL−1): Cd (1200), Cr (1000), Cu (1000), Pb (800), and Hg (30). Based on phenotypic and biochemical characteristics, as well as 16S rDNA gene sequencing, endophytic isolate BPR-9 was recognized as Priestia aryabhattai (accession no. OM743254.1). This isolate was revealed as a powerful multi-stress-tolerant crop growth promoter after extensive in-vitro testing for plant growth-promoting attributes, nutrient (phosphate, P; potassium, K; and zinc, Zn) solubilization efficiency, extracellular enzyme (protease, cellulase, amylase, lipase, and pectinase) synthesis, and potential for antagonistic activity against important fungal pathogens viz. Alternaria solani, Rhizoctonia solani, Fusarium oxysporum, and Ustilaginoidea virens. At elevated salt levels, increases were noted in indole-3-acetic acid; siderophores; P, K, and Zn-solubilization; ACC deaminase; and ammonia synthesized by Priestia aryabhattai. Additionally, under in-vitro plant bioassays, wheat seedlings inoculated with P. aryabhattai experienced superior growth compared to non-inoculated seedlings in high salinity (0–15% NaCl) environment. Under NaCl stress, germination rate, plant length, vigor indices, and leaf pigments of wheat seedlings significantly increased following P. aryabhattai inoculation. Furthermore, at 2%-NaCl, B. aryabhattai greatly and significantly (p ≤ 0.05) decreased relative leaf water content, membrane damage, and electrolyte leakage compared with the non-inoculated control. Catalase, superoxide dismutase, and peroxidase activity increased by 29, 32, and 21%, respectively, in wheat seedlings exposed to 2% NaCl and inoculated with the bacteria. The present findings demonstrate that endophytic P. aryabhattai strains might be used in the future as a multi-stress reducer and crop growth promoter in agronomically important crops including cereals.

Quorum Sensing Regulates the Hydrolytic Enzyme Production and Community Composition of Heterotrophic Bacteria in Coastal Waters.

Heterotrophic microbial communities play a central role in biogeochemical cycles in the ocean by degrading organic matter through the synthesis of extracellular hydrolytic enzymes. Their hydrolysis rates result from the community’s genomic potential and the differential expression of this genomic potential. Cell-cell communication pathways such as quorum sensing (QS) could impact both aspects and, consequently, structure marine ecosystem functioning. However, the role of QS communications in complex natural assemblages remains largely unknown. In this study, we investigated whether N-acylhomoserine lactones (AHLs), a type of QS signal, could regulate both hydrolytic activities and the bacterial community composition (BCC) of marine planktonic assemblages. To this extent, we carried out two microcosm experiments, adding five different AHLs to bacterial communities sampled in coastal waters (during early and peak bloom) and monitoring their impact on enzymatic activities and diversity over 48 h. Several specific enzymatic activities were impacted during both experiments, as early as 6 h after the AHL amendments. The BCC was also significantly impacted by the treatments after 48 h, and correlated with the expression of the hydrolytic activities, suggesting that changes in hydrolytic intensities may drive changes in BCC. Overall, our results suggest that QS communication could participate in structuring both the function and diversity of marine bacterial communities.

Analysis of transcriptional regulators HpaR1 and Clp regulating the expression of glycoside hydrolase-encoding gene in the Xanthomonas campestris pv. campestris.

Xanthomonas campestris pv. campestris (Xcc) is a vascular pathogen that causes black rot in host. It is an important model strain for studying the interaction between the phytopathogen and plants. In Xcc, global transcription regulator HpaR1 that belongs to the GntR family regulates many cellular processes such as the movement and synthesis of extracellular polysaccharides and extracellular enzymes, and is associated with hypersensitive response (HR) and pathogenicity. On the other hand, the global transcriptional regulator Clp regulates the secretion and synthesis of extracellular enzymes and extracellular polysaccharides, and is associated with the pathogenicity of Xanthomonas. Previous studies have shown that both HpaR1 and Clp bind to the promoter region of the glycoside hydrolase encoding gene (named ghy gene). This study investigates the molecular mechanism of the co-regulation of HpaR1 and Clp on the expression of ghy gene. Through electrophoresis mobility shift assay (EMSA), we found that both HpaR1 and Clp bind to the promoter regions of gene ghy in vitro. Both HpaR1 and Clp also bind to the promoter regions of gene ghy in vivo by chromatin immunoprecipitation (ChIP) assays. DNase I footprinting and 5'-RACE assays showed that both HpaR1 and Clp bind to the -35 region upstream of the ghy promoter. The HpaR1 binding site was located upstream of the Clp binding site. RT-qPCR and in vitro transcription assays showed that HpaR1 negatively while Clp positively regulates the transcription of gene ghy. Furthermore, HpaR1 inhibits the activation of Clp on the transcription of gene ghy in vitro. Our findings indicate that HpaR1 and Clp exhibit opposite effect on the transcription of gene ghy. It is speculated that HpaR1 may regulate the expression of gene ghy by inhibiting the activity of RNA polymerase.

Isolation of Halophilic Bacteria and Their Screening for Extracellular Enzyme Production

Halophiles are those microorganisms which are found at high salt concentration. These microorganisms have the capability to form a wide array of bioactive substances that have different applications in various industries. This work focussed at the isolation and screening of various halophilic bacterial strains from different places in Rajasthan and Tamil Nadu. Using a complete medium with different salt concentrations, 70 halophilic bacteria were isolated from 4 different sites. These isolated bacteria were then examined and screened out for the synthesis of different extracellular enzymes, such as cellulase, lipase and amylase. Out of the total, 24 isolates were found positive for amylase, 9 for lipase and 16 for cellulase. These enzymes can perform the hydrolytic activity at high salt concentrations. The various halophilic bacterial strains isolated from various places show a prospective for use in a range of biotechnological and molecular biology experiments and the extremozymes obtained from these bacteria have great industrial importance.

Rye Snow Mold-Associated Microdochium nivale Strains Inhabiting a Common Area: Variability in Genetics, Morphotype, Extracellular Enzymatic Activities, and Virulence.

Snow mold is a severe plant disease caused by psychrophilic or psychrotolerant fungi, of which Microdochium species are the most harmful. A clear understanding of Microdochium biology has many gaps; the pathocomplex and its dynamic are poorly characterized, virulence factors are unknown, genome sequences are not available, and the criteria of plant snow mold resistance are not elucidated. Our study aimed to identify comprehensive characteristics of a local community of snow mold-causing Microdochium species colonizing a particular crop culture. By using the next-generation sequencing (NGS) technique, we characterized fungal and bacterial communities of pink snow mold-affected winter rye (Secale cereale) plants within a given geographical location shortly after snowmelt. Twenty-one strains of M. nivale were isolated, classified on the basis of internal transcribed spacer 2 (ITS2) region, and characterized by morphology, synthesis of extracellular enzymes, and virulence. Several types of extracellular enzymatic activities, the level of which had no correlations with the degree of virulence, were revealed for Microdochium species for the first time. Our study shows that genetically and phenotypically diverse M. nivale strains simultaneously colonize winter rye plants within a common area, and each strain is likely to utilize its own, unique strategy to cause the disease using “a personal” pattern of extracellular enzymes.

Penicillium oxalicum S-adenosylmethionine synthetase is essential for the viability of fungal cells and the expression of genes encoding cellulolytic enzymes

As the universal methyl donor for methylation reactions, S-adenosylmethionine (AdoMet) plays an indispensable role in most cellular metabolic processes. AdoMet is synthesized by AdoMet synthetase. We identified the only one AdoMet synthetase (PoSasA) in filamentous fungus Penicillium oxalicum. PoSasA was widely distributed in mycelium at different growth stages. The absence of PoSasA was lethal for P. oxalicum. The misregulation of the PoSasA encoding gene affected the synthesis of extracellular cellulolytic enzymes. The expression levels of cellobiohydrolase encoding gene cbh1/cel7A, β-1-4 endoglucanase eg1/cel7B, and xylanase encoding gene xyn10A were remarkably downregulated as a result of decreased PosasA gene expression. The production of extracellular cellulases and hemicellulases was also reduced. By contrast, the overexpression of PosasA improved the production of extracellular cellulases and hemicellulases. A total of 133 putative interacting proteins with PoSasA were identified using tandem affinity purification and mass spectrometry. The results of functional enrichment on these proteins showed that they were mainly related to ATP binding, magnesium ion binding, and ATP synthetase activity. Several methyltransferases were also observed among these proteins. These results were consistent with the intrinsic feature of AdoMet synthetase. This work reveals the indispensable role of PoSasA in various biological processes.

Microorganisms and Enzymes Used in the Biological Pretreatment of the Substrate to Enhance Biogas Production: A Review

The pretreatment of lignocellulosic biomass (LC biomass) prior to the anaerobic digestion (AD) process is a mandatory step to improve feedstock biodegradability and biogas production. An important potential is provided by lignocellulosic materials since lignocellulose represents a major source for biogas production, thus contributing to the environmental sustainability. The main limitation of LC biomass for use is its resistant structure. Lately, biological pretreatment (BP) gained popularity because they are eco-friendly methods that do not require chemical or energy input. A large number of bacteria and fungi possess great ability to convert high molecular weight compounds from the substrate into lower mass compounds due to the synthesis of microbial extracellular enzymes. Microbial strains isolated from various sources are used singly or in combination to break down the recalcitrant polymeric structures and thus increase biogasgeneration. Enzymatic treatment of LC biomass depends mainly on enzymes like hemicellulases and cellulases generated by microorganisms. The articles main purpose is to provide an overview regarding the enzymatic/biological pretreatment as one of the most potent techniques for enhancing biogas production.

Quality of fresh plant residue affects sequestration of residue derived organic material by humic acid

Increasing the retention and sequestration of plant residue carbon in agricultural soils by incorporating humic acid is the main focus of this study. This study aims to examine the effect of humic acid addition on the decomposition of plant residues of varying degrees of lability. Respiration experiments were conducted to estimate the ability of humic acid to protect plant derived organic compounds from decomposition. Humic acid reduced mineralization from all added residues and this protection effect followed the lability of the residues: vetch> wheat> oak. This could be attributed to the chemical interaction between different plant-derived organic compounds and the humic acid. Lysine was strongly adsorbed to humic acid and mineralization was reduced by 23% as a result of the strong electrostatic interaction. Applying humic acid with vetch reduced all microbial indices as a result of less substrate availability for miroorganisms. On the other hand, applying humic acid with wheat might have simulated the synthesis of extracellular enzymes and the co-metabolism of humic acid (brimming effect), resulting in an enhanced microbial structure toward a higher fungal population. This study suggests: (1) Applying humic acid to ecosystems that receive labile residues (such as vetch) to reduce mineralization and enhance carbon sequestration (2) Applying less labile residues (such as wheat) in combination with humic acid to recover degraded soils and enhance carbon sequestration.

Nitrogen supply rate regulates microbial resource allocation for synthesis of nitrogen-acquiring enzymes.

Although microorganisms will preferentially allocate resources to synthesis of nitrogen (N)-acquiring enzymes when soil N availability is low according to the resource allocation model for extracellular enzyme synthesis, a robust link between microbial N-acquiring enzyme activity and soil N concentration has not been reported. To verify this link, we measured several indices of soil N availability and enzyme activity of four N-acquiring enzymes [N-acetyl-β-glucosaminidase (NAG), protease (PR), urease (UR), and L-asparaginase (LA)] and a carbon (C)-acquiring enzyme [β-D-glucosidase (BG)] in arable and forest soils. Although the ratios of NAG/BG and PR/BG were not significantly related with indices of soil N availability, ratios of LA/BG and UR/BG were strongly and negatively related with potentially mineralizable N estimated by aerobic incubation but not with pools of labile inorganic N and organic N. These results suggest that microorganisms might allocate their resources to LA and UR synthesis in response to N supply rate rather than the size of the easily available N pools. It was also suggested that the underlying mechanism for synthesis was different between these N-acquiring enzymes in soil microorganisms: microbial LA and UR were primarily synthesized to acquire N, whereas NAG and PR syntheses were regulated not only by N availability but also by other factors.

Microbial resource allocation for phosphatase synthesis reflects the availability of inorganic phosphorus across various soils

According to the resource allocation model for extracellular enzyme synthesis, microorganisms should preferentially allocate their resources to phosphorus (P)-acquiring enzyme synthesis when P availability is low in soils. However, the validity of this model across different soil types and soils differing in their microbial community composition has not been well demonstrated. Here we investigated whether the resource allocation model for phosphatase synthesis is applicable across different soil types (Andosols, Acrisols, Cambisols, and Fluvisols) and land uses (arable and forest), and we examined which soil test P and/or P fraction microorganisms responded to when investing their resources in phosphatase synthesis in the soils. The ratio of alkaline phosphatase (ALP) to β-d-glucosidase (BG) activities in the arable soils and the ratio of acid phosphatase (ACP) to BG activities in the forest soils were significantly negatively related with the available inorganic P concentration. We also observed significant effects of available inorganic P, pH, soil types, and land uses on the (ACP + ALP)/BG ratio when the data for the arable and forest soils were combined and used in a stepwise multiple regression analysis. These results suggest that microbial resource allocation for phosphatase synthesis is primarily controlled by available inorganic P concentration and soil pH, but the effects of soil types and land uses are also significant.

Simultaneous Cr(VI) removal and 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47) biodegradation by Pseudomonas aeruginosa in liquid medium

Simultaneous Cr(VI) removal and 2,2′,4,4′-tetra brominated diphenyl ether (BDE-47) biodegradation by Pseudomonas aeruginosa in liquid medium were investigated in this study, with the goal of elucidating the interaction between concomitant pollutants Cr(VI) and BDE-47 during microbial remediation. The experimental results revealed that the degradation efficiency of 1 mg L−1 BDE-47 by 60 mg L−1 biomass achieved 51.3% within 7 d when 2 mg L−1 Cr(VI) coexisted. The degradation efficiency was accelerated at low concentrations of Cr(VI) (≤5 mg L−1), but inhibited at higher levels (≥10 mg L−1). Cr(VI) of 2 mg L−1 facilitated the secretion of rhamnolipid from the strain, altered cell surface hydrophobicity and cell membrane permeability, and promoted intracellular BDE-47 accumulation, thus improving BDE-47 biotransformation. In addition, the stimulation of intracellular enzyme synthesis by 2 mg L−1 Cr(VI) contributed to more BDE-47 elimination in the cells. The achievement of BDE-47 biodegradation was coupled with cell growth, enzyme extraction, cell membrane permeability change, and ATPase activity increase. The study also indicated that the improvement of Cr(VI) removal in BDE-47/Cr(VI) co-contaminated condition was mostly due to the increasing synthesis of extracellular enzyme in the presence of low concentrations of BDE-47. The whole study demonstrated that P. aeruginosa was available for the removal of toxic Cr(VI) and degradation of BDE-47 simultaneously in the liquid.

Multiple environmental changes induce interactive effects on bacterial degradation activity in the Arctic Ocean

AbstractThe Arctic Ocean faces multiple environmental changes induced by climate change on both global and regional scale. In addition to global changes in seawater temperature and pH, Arctic waters receive organic matter enrichment due to increasing pelagic primary production, enhanced sea ice melting and increasing terrestrial carbon loads. We experimentally tested individual and combined effects of warming, acidification and organic matter amendment on growth, biomass production and extracellular enzyme activities of bacterioplankton in Fram Strait during early summer. Results reveal pH optima of 6.7–7.6 for extracellular leucine‐aminopeptidase and below pH 6.0 for beta‐glucosidase in the West Spitsbergen Current. These optima well below the current seawater pH imply increasing hydrolytic activity with ongoing ocean acidification. However, the new synthesis of extracellular enzymes during 4‐d incubations obscured the biochemical pH effects. Elevated temperature and carbohydrate supply had strongly interactive effects on bacterial biomass production in both Atlantic Water of the West Spitsbergen Current and Polar Water of the East Greenland Current. Activation energies ranged from 45 kJ mol−1 to 52 kJ mol−1 at in situ substrate concentration, while substantially higher values of 122–174 kJ mol−1 could be estimated from incubations with carbohydrate addition. The net loss of total amino acids in carbohydrate‐amended incubations was significantly reduced at elevated temperature in all experiments, suggesting enhanced de novo synthesis. Our findings show that the complexity of combined effects must be considered to better assess the potential of climate change to alter biogenic carbon and energy fluxes in marine systems.

Unravelling the genetic basis for competence development of auxotrophic Bacillus licheniformis 9945A strains

Bacterial natural genetic competence - well studied in Bacillus subtilis - enables cells to take up and integrate extracellularly supplied DNA into their own genome. However, little is known about competence development and its regulation in other members of the genus, although DNA uptake machineries are routinely encoded. Auxotrophic Bacillus licheniformis 9945A derivatives, obtained from repeated rounds of random mutagenesis, were long known to develop natural competence. Inspection of the colony morphology and extracellular enzyme secretion of two of these derivatives, M28 and M18, suggested that regulator genes are collaterally hit. M28 emerged as a 14 bp deletion mutant concomitantly displaying a shift in the reading frame of degS that encodes the sensor histidine kinase, which is part of the molecular switch that directs cells to genetic competence, the synthesis of extracellular enzymes or biofilm formation, while for M18, sequencing of the suspected gene revealed a 375 bp deletion in abrB, encoding the major transition state regulator. With respect to colony morphology, enzyme secretion and competence development, both of the mutations, when newly generated on the wild-type B. licheniformis 9945A genetic background, resulted in phenotypes resembling M28 and M18, respectively. All of the known naturally competent B. licheniformis representatives, hitherto thoroughly investigated in this regard, carry mutations in regulator genes, and hence genetic competence observed in domesticated strains supposedly results from deregulation.

Growth and oxidative enzymatic activity of in-vitro cultures of Ciliochorella buxifolia

To get a better insight into the physiological capabilities of Ciliochorella buxifolia, the most frequent fungus occurring on Scutia buxifolia leaf-litter in a native forest from Argentina, its in-vitro ability to use 10 carbon sources and to produce extracellular enzymes, including its response to tannic acid and to the addition of a water-soluble fraction of Scutia buxifolia leaf-litter, was analyzed. Growth, colony morphology and extracellular enzyme activity as well as differentiation of pycnidia were a function of the C substrate. The fungus responded to the presence of tannic acid in a range between 0.001 and 0.1% (w/v), by increasing growth, but higher phenol concentrations like 0.5% were inhibitory. The activity of extracellular oxidative enzymes increased with the concentration of tannic acid. Furthermore, the fungus showed extracellular laccase and peroxidase activity, being the former increased by water-soluble fraction in association to pycnidia development. Based on these results, Ciliochorella buxifolia is a fungus growing on Scutia buxifolia leaf-litter that is able to metabolize soluble phenolic compounds, which triggers the synthesis of extracellular oxidative enzymes possibly involved in sporulation and detoxification reactions.