Diversity, prevalence, and expression of cyanase genes (cynS) in planktonic marine microorganisms

Cyanate is utilized by many microbes as an organic nitrogen source. The key enzyme for cyanate metabolism is cyanase, converting cyanate to ammonium and carbon dioxide. Although the cyanase gene cynS has been identified in many species, the diversity, prevalence, and expression of cynS in marine microbial communities remains poorly understood. Here, based on the full-length cDNA sequence of a dinoflagellate cynS and 260 homologs across the tree of life, we extend the conserved nature of cyanases by the identification of additional ultra-conserved residues as part of the modeled holoenzyme structure. Our phylogenetic analysis showed that horizontal gene transfer of cynS appears to be more prominent than previously reported for bacteria, archaea, chlorophytes, and metazoans. Quantitative analyses of marine planktonic metagenomes revealed that cynS is as prevalent as ureC (urease subunit alpha), suggesting that cyanate plays an important role in nitrogen metabolism of marine microbes. Highly abundant cynS transcripts from phytoplankton and nitrite-oxidizing bacteria identified in global ocean metatranscriptomes indicate that cyanases potentially occupy a key position in the marine nitrogen cycle by facilitating photosynthetic assimilation of organic N and its remineralisation to NO3 by the activity of nitrifying bacteria.

Synergistic Effects of Adding A Substrate and an Organic Reductant for Stimulating the Bioremediation of 4-Chloronitrobenzene-Contaminated Soil

Background: Soil contaminated with 4-chloronitrobenzene (4NCB) is resistant to microbial degradation due to the electron-withdrawing properties of the nitro and chloro groups in 4NCB. Currently, sufficient information is not available on how to use biostimulation strategies to enhance the bioremediation of 4NCB-contaminated soil.Results: In the present study, a novel strategy was developed by utilizing the synergistic effects of adding an organic reductant (ascorbic acid, VC) and an organic nitrogen source (peptone) to stimulate the biodegradation of 4NCB-contaminated soil. Using this strategy, the bioremediation of 1 g-4NCB/ kg-1 soil could be completed within 8 days in soil batch reactors. Furthermore, the study discovered two 4NCB cometabolic intermediates in the soil reactors added with peptone and VC, and for the first time, 4NCB was transformed to 4-chlorofromanilide.Conclusion: The proposed strategy is promising because it is highly efficient, easy to control and involves a non-toxic, environmentally friendly substrate/reductant.). Finally, this approach warrants future studies to extend its applications to soils contaminated with other nitroaromatic compounds.

Synergistic Effects of Adding a Substrate and an Organic Reductant for Stimulating the Bioremediation of 4-chloronitrobenzene-contaminated Soil

Background:Soil contaminated with 4-chloronitrobenzene (4NCB) is resistant to microbial degradation due to the electron-withdrawing properties of the nitro and chloro groups in 4NCB. Currently, sufficient information is not available on how to use biostimulation strategies to enhance the bioremediation of 4NCB-contaminated soil.Results:In the present study, a novel strategy was developed by utilizing the synergistic effects of adding an organic reductant (ascorbic acid, VC) and an organic nitrogen source (peptone) to stimulate the biodegradation of 4NCB-contaminated soil. Using this strategy, the bioremediation of 1 g-4NCB/ kg-1 soil could be completed within 8 days in soil batch reactors. Furthermore, the study discovered two 4NCB cometabolic intermediates in the soil reactors added with peptone and VC, and for the first time, 4NCB was transformed to 4-chlorofromanilide.Conclusion:The proposed strategy is promising because it is highly efficient, easy to control and involves a non-toxic, environmentally friendly substrate/reductant.). Finally, this approach warrants future studies to extend its applications to soils contaminated with other nitroaromatic compounds.

Mechanisms for Induction of Microbial Extracellular Proteases in Response to Exterior Proteins

ABSTRACT Proteins are a main organic nitrogen source for microorganisms. Many heterotrophic microorganisms secrete extracellular proteases (ex-proteases) to efficiently decompose proteins into oligopeptides and amino acids when exterior proteins are required for growth. These ex-proteases not only play important roles in microbial nutrient acquisition or host infection but also contribute greatly to the global recycling of carbon and nitrogen. Moreover, may microbial ex-proteases have important applications in industrial, medical, and biotechnological areas. Therefore, uncovering the mechanisms by which microorganisms initiate the expression of ex-protease genes in response to exterior proteins is of great significance. In this review, the progress made in understanding the induction mechanisms of microbial ex-proteases in response to exterior proteins is summarized, with a focus on the inducer molecules, membrane sensors, and downstream pathways. Problems to be solved for better understanding of the induction mechanisms of microbial ex-proteases are also discussed.

Influence of the Nutrients on the Biomass and Pigment Production of Chlorociboria aeruginascens

The blue-green pigment xylindein, produced by the soft rot fungus Chlorociboria aeruginascens, is of considerable interest for various applications such as the veneer industry or organic semiconductors. The studies presented were performed in order to understand the fungal growth as well as the pigment production of C. aeruginascens. Therefore, various nutrient compositions were investigated. As a result, observations of the formation of xylindein through C. aeruginascens decoupling from growth were made. In the primary metabolism the uncolored biomass is formed. Various carbohydrates were determined as nutrients for the fungus and as a nitrogen source it was observed that the fungus prefers the complex organic nitrogen source, that being yeast extract. Furthermore, it was discovered that the ratio between carbohydrate and nitrogen sources encourages the switch of the metabolism and therewith the production of the blue-green pigment xylindein.

Effect of glutamine and arginine on growth of Hibiscus moscheutos “in vitro”

Nitrogen is the most essential element for plant growth and development. Amino acids, serving as the main organic nitrogen source in tissue culture media, provide for shoot and root elongation. Glutamine has been widely used in tissue culture for dedifferentiation and re-differentiation processes. Experiments were conducted to assess the effects of glutamine in comparison to some commonly used plant growth regulators (PGRs) on the growth of Hibiscus moscheutos propagated via tissue culture. An initial study suggested that 10 mg L-1 glutamine in MS basal medium was optimal for shoot elongation. At this optimal rate, glutamine showed superiority over other PGRs. No difference was found between glutamine treatments and the control in a later study. When comparing glutamine with arginine, shoots cultured on media with arginine displayed slightly greater growth. With arginine containing two extra nitrogen groups in its molecular structure, the higher percentage of nitrogen may have resulted in improved growth.