Nitrogen Source For Growth Research Articles

Metabolic pathway engineering of high-salinity-induced overproduction of L-proline improves high-salinity stress tolerance of an ectoine-deficient Halomonas elongata.

Halophilic bacteria have adapted to survive in high-salinity environments by accumulating amino acids and their derivatives as organic osmolytes. L-Proline (Pro) is one such osmolyte that is also being used as a feed stimulant in the aquaculture industry. Halomonas elongata OUT30018 is a moderately halophilic bacterium that accumulates ectoine (Ect), but not Pro, as an osmolyte. Due to its ability to utilize diverse biomass-derived carbon and nitrogen sources for growth, H. elongata OUT30018 is used in this work to create a strain that overproduces Pro, which could be used as a sustainable Pro-rich feed additive. To achieve this, we replaced the coding region of H. elongata OUT30018's Ect biosynthetic operon with the artificial self-cloned proBm1AC gene cluster that encodes the Pro biosynthetic enzymes: feedback-inhibition insensitive mutant γ-glutamate kinase (γ-GKD118N/D119N), γ-glutamyl phosphate reductase, and pyrroline-5-carboxylate reductase. Additionally, the putA gene, which encodes the key enzyme of Pro catabolism, was deleted from the genome to generate H. elongata HN6. While the Ect-deficient H. elongata KA1 could not grow in minimal media containing more than 4% NaCl, H. elongata HN6 thrived in the medium containing 8% NaCl by accumulating Pro in the cell instead of Ect, reaching a concentration of 353.1 ± 40.5 µmol/g cell fresh weight, comparable to the Ect accumulated in H. elongata OUT30018 in response to salt stress. With its genetic background, H. elongata HN6 has the potential to be developed into a Pro-rich cell factory for upcycling biomass waste into single-cell feed additives, contributing to a more sustainable aquaculture industry.IMPORTANCEWe report here the evidence for de novo biosynthesis of Pro to be used as a major osmolyte in an ectoine-deficient Halomonas elongata. Remarkably, the concentration of Pro accumulated in H. elongata HN6 (∆ectABC::mCherry-proBm1AC ∆putA) is comparable to that of ectoine accumulated in H. elongata OUT30018 in response to high-salinity stress. We also found that among the two γ-glutamate kinase mutants (γ-GKD118N/D119N and γ-GKD154A/E155A) designed to resemble the two known Escherichia coli feedback-inhibition insensitive γ-GKD107N and γ-GKE143A, the γ-GKD118N/D119N mutant is the only one that became insensitive to feedback inhibition by Pro in H. elongata. As Pro is one of the essential feed additives for the poultry and aquaculture industries, the genetic makeup of the engineered H. elongata HN6 would allow for the sustainable upcycling of high-salinity waste biomass into a Pro-rich single-cell eco-feed.

Antibiotics promote intestinal growth of carbapenem-resistant Enterobacteriaceae by enriching nutrients and depleting microbial metabolites

The intestine is the primary colonisation site for carbapenem-resistant Enterobacteriaceae (CRE) and serves as a reservoir of CRE that cause invasive infections (e.g. bloodstream infections). Broad-spectrum antibiotics disrupt colonisation resistance mediated by the gut microbiota, promoting the expansion of CRE within the intestine. Here, we show that antibiotic-induced reduction of gut microbial populations leads to an enrichment of nutrients and depletion of inhibitory metabolites, which enhances CRE growth. Antibiotics decrease the abundance of gut commensals (including Bifidobacteriaceae and Bacteroidales) in ex vivo cultures of human faecal microbiota; this is accompanied by depletion of microbial metabolites and enrichment of nutrients. We measure the nutrient utilisation abilities, nutrient preferences, and metabolite inhibition susceptibilities of several CRE strains. We find that CRE can use the nutrients (enriched after antibiotic treatment) as carbon and nitrogen sources for growth. These nutrients also increase in faeces from antibiotic-treated mice and decrease following intestinal colonisation with carbapenem-resistant Escherichia coli. Furthermore, certain microbial metabolites (depleted upon antibiotic treatment) inhibit CRE growth. Our results show that killing gut commensals with antibiotics facilitates CRE colonisation by enriching nutrients and depleting inhibitory microbial metabolites.

Nitenpyram biodegradation by a novel nitenpyram-degrading bacterium, Ochrobactrum sp. strain DF-1, and its novel degradation pathway.

Nitenpyram is a neonicotinoid insecticide that is commonly found in the environment. However, its biodegradation by pure cultures of bacteria has not been widely investigated and the catabolic pathway (s) for nitenpyram metabolism remain elusive. In this study, the aerobic strain DF-1, isolated from a wastewater-treatment pool contaminated with nitenpyram. The strain was designated an Ochrobactrum sp. utilizing a combination of traditional methods and molecular ones. Strain DF-1 can use nitenpyram as a sole carbon or nitrogen source for growth. In liquid medium, 100 mg·L-1 nitenpyram was metabolized to undetectable levels within 10 days. Four metabolites were found by gas chromatography-mass spectrometry (GC-MS) analyses during nitenpyram degradation. According to the aforementioned data, a partial metabolic pathway of nitenpyram was proposed of strain DF-1. Inoculation of strain DF-1 promoted nitenpyram (10 mg·kg-1) degradation in either sterile or non-sterile soil. To our knowledge, this is the first characterization of nitenpyram degradation by a specific bacterium and likely to be exploited for the remediation of nitenpyram-contaminated sites.

Utilization of Carbohydrates in Bamboo Shoots (Dendrocalamus asper) As an Alternative Media for the Growth of Candida albicans fungus

Candidiasis disease caused by the fungus Candida albicans is a health problem in Indonesia. The chronic nature of the disease gets worse if it is accompanied by a fungal infection, which usually goes undiagnosed and untreated. Culture techniques can be used to identify the fungus Candida albicans. Mushroom culture in the laboratory requires a medium containing nutrients such as a carbohydrate source and a nitrogen source for growth. These nutrients can be found in bamboo shoots which contain high carbohydrates, protein, fat, vitamins, and crude fiber. So that bamboo shoots can be used as raw material for alternative mushroom growth media. The purpose of this study was to utilize bamboo shoots as a medium for the growth of Candida albicans herbal medicine. This research included collecting bamboo shoots, making rice bran media, inoculation of Candida albicans fungus on bamboo shoots media, and observing fungal growth. Candida albicans fungal colonies were confirmed by macroscopic and microscopic observations. The results showed that the fungus Candida albicans grew on both media, namely Bamboo Shoots Flour Media and Sabouraud Dextrose Agar (SDA) media at 37oC for 48 hours. The conclusion of this study is that bamboo shoots media can be used as a medium for fungal growth. Bamboo shoots media can be used as an alternative medium for synthetic media to grow Candida albican

Stable isotope-assisted metabolite profiling reveals new insights into L-tryptophan chemotrophic metabolism of Rubrivivax benzoatilyticus

Anoxygenic photosynthetic bacteria (APB) are metabolically versatile, capable of surviving with an extended range of carbon and nitrogen sources. This group of phototrophic bacteria have remarkable metabolic plasticity in utilizing an array of organic compounds as carbon source/electron donors and nitrogen sources with sophisticated growth modes. Rubrivivax benzoatilyticus JA2 is one such photosynthetic bacterium utilizes L-tryptophan as nitrogen source under phototrophic growth mode and produces an array of indolic compounds of biotechnological significance. However, chemotrophic L-tryptophan metabolism is largely unexplored and studying L-tryptophan metabolism under chemotrophic mode would provide new insights into metabolic potential of strain JA2. In the present study, we employed stable-isotopes assisted metabolite profiling to unravel the L-tryptophan catabolism in Rubrivivax benzoatilyticus strain JA2 under chemotrophic (dark aerobic) conditions. Utilization of L-tryptophan as a nitrogen source for growth and simultaneous production of indole derivatives was observed in strain JA2. Liquid chromatography mass spectrometry (LC-MS) analysis of exo-metabolite profiling of carbon labeled L-tryptophan (13C11) fed cultures of strain JA2 revealed at least seventy labeled metabolites. Of these, only fourteen metabolites were confirmed using standards, while sixteen were putative and forty metabolites remained unidentified. L-tryptophan chemotrophic catabolism revealed multiple catabolic pathways and distinct differential catabolism of L-tryptophan under chemotropic state as compared to photo-catabolism of L-tryptophan in strain JA2.

Metabolic phenotype analysis of Trichophyton rubrum after laser irradiation

BackgroundBiological phenotypes are important characteristics of microorganisms, and often reflect their genotype and genotype changes. Traditionally, Trichophyton rubrum (T. rubrum) phenotypes were detected using carbon source assimilation tests, during which the types of tested substances are limited. In addition, the operation is complicated, and only one substance can be tested at once. To observe the changes of the metabolic phenotype of T. rubrum after laser irradiation, a high-throughput phenotype microarray system was used to analyze the metabolism of different carbon, nitrogen, phosphorus and sulfur source substrates in a Biolog metabolic phenotyping system.ResultsThe strain of T. rubrum used in this study can effectively utilize 33 carbon, 20 nitrogen, 16 phosphorus, and 13 sulfur source substrates prior to laser irradiation. After laser irradiation, the strain was able to utilize 10 carbon, 12 nitrogen, 12 phosphorus, and 8 sulfur source substrates. The degree of utilization was significantly decreased compared with the control. Both groups efficiently utilized saccharides and organic acids as carbon sources as well as some amino acids as nitrogen sources for growth. The number of substrates utilized by T. rubrum after laser irradiation were significantly reduced, especially carbon substrates. Some substrates utilization degree in the laser treated group was higher than control, such as D-glucosamine, L-glutamine, D-2-Phospho-Glyceric Acid, D-glucosamine-6-phosphate, and D-methionine.ConclusionLaser irradiation of T. rubrum may lead to changes in the metabolic substrate and metabolic pathway, thus weakening the activity of the strain.

Combination of poly-γ-glutamic acid and galactooligosaccharide improves intestinal microbiota, defecation status, and relaxed mood in humans: a randomized, double-blind, parallel-group comparison trial.

The genus Bifidobacterium comprises beneficial intestinal bacteria that play a crucial role in the regulation of human health. Traditional prebiotics are known to increase intestinal bifidobacteria by supplying a carbon source necessary for their growth. However, intestinal bifidobacteria need not only a carbon source but also a nitrogen source for growth. Moreover, the growth of bifidobacteria is known to be inhibited in a culture medium that does not contain glutamic acid. Based on these reports, we hypothesized that the combined intake of traditional prebiotics and glutamic acid would be beneficial for growth of bifidobacteria in the gut. In this study, we investigated the effects of the combination of galactooligosaccharide (GOS; traditional prebiotic material) and poly-γ-glutamic acid (γ-PGA; source of glutamic acid) and only GOS on the intestinal microbiota and health conditions (including intestinal regulation, mood status, gastrointestinal condition, skin condition, and sleep quality) in a randomized, double-blind, parallel-group comparison trial in healthy subjects. The combined intake of GOS and γ-PGA significantly increased the prevalence of B. longum compared to the intake of GOS alone. A minimum effective dose of 2.0 g GOS and 0.3 g γ-PGA improved defecation and mood status. We revealed the combined effects of GOS and γ-PGA on intestinal microbiota as well as physical condition and concluded that the delivery of glutamic acid to the large intestine with traditional prebiotics is useful as an advanced prebiotic.

Growth, Sporulation, Conidial Germination and Lethal Temperature of Paraphoma radicina, A Fungal Pathogen of Alfalfa (Medicago sativa) Root Rot

In 2020, alfalfa root rot, a disease caused by Paraphoma radicina, was identified in Inner Mongolia, China, where it seriously affected alfalfa crop yields. Conditions for in vitro growth, sporulation and conidial germination of P. radicina are poorly understood, limiting further studies. In this contribution, we evaluated the suitability of different media, carbon and nitrogen sources, as well as temperature and pH for P. radicina in vitro growth and germination. In addition, the temperature sensitivity of these cultures was assessed. Paraphoma radicina growth and sporulation were most vigorous on the ARDA medium, reaching the maximum growth and sporulation rates after 4 weeks of incubation. All carbon and nitrogen sources supported growth, but none induced sporulation. The best carbon and nitrogen sources for growth were mannitol and peptone, respectively. Conidial germination was observed in the 4 to 35 °C temperature range, with an optimum temperature of 25 °C. The germination rate was highest at pH 7, and more than 50% of conidia germinated after 38 h of incubation at 25 °C. On the other hand, temperatures above 55 °C (10 min) and 41 °C (10 min) proved lethal for the mycelial and conidial forms of the pathogen, respectively. These results can provide clues to the environmental conditions amenable for P. radicina infection of alfalfa crops and, on the whole, a better understanding of pathogenicity.

Investigating the effect of nickel concentration on phytoplankton growth to assess potential side-effects of ocean alkalinity enhancement

Abstract. Ocean alkalinity enhancement (OAE) is a proposed method for removing carbon dioxide (CO2) from the atmosphere by the accelerated weathering of (ultra-)basic minerals to increase alkalinity – the chemical capacity of seawater to store CO2. During the weathering of OAE-relevant minerals relatively large amounts of trace metals will be released and may perturb pelagic ecosystems. Nickel (Ni) is of particular concern as it is abundant in olivine, one of the most widely considered minerals for OAE. However, so far there is limited knowledge about the impact of Ni on marine biota including phytoplankton. To fill this knowledge gap, this study tested the growth and photo-physiological response of 11 marine phytoplankton species to a wide range of dissolved Ni concentrations (from 0.07 to 50 000 nmol L−1). We found that the phytoplankton species were not very sensitive to Ni concentrations under the culturing conditions established in our experiments, but the responses were species-specific. The growth rates of 6 of the 11 tested species showed generally limited but still significant responses to changing Ni concentrations (36 % maximum change). Photosynthetic performance, assessed by measuring the maximum quantum yield (Fv/Fm) and the functional absorption cross-section (σPSII) of photosystem II (PSII), was sensitive to changing Ni in 3 out of 11 species (35 % maximum change) and 4 out of 11 species (16 % maximum change), respectively. The limited effect of Ni may be partly due to the provision of nitrate as the nitrogen source for growth as previous studies suggest higher sensitivities when urea is the nitrogen source. Furthermore, the limited influence may be due to the relatively high concentrations of synthetic organic ligands added to the growth media in our experiments. These ligands are commonly added to control trace metal bioavailability and therefore for example “free Ni2+” concentrations by binding the majority of the dissolved Ni. Our data suggest that dissolved Ni does not have a strong effect on phytoplankton under our experimental conditions, but we emphasize that a deeper understanding of nitrogen sources, ligand concentrations, and phytoplankton composition is needed when assessing the influence of Ni release associated with OAE.

Using Locusta Migratoria as a Nitrogen Source for the Growth and Development of Microorganisms

Characteristics and the use as culture media of protein hydrolysate from Locusta migratoria were determined in comparison with different peptones. After powdering, it was hydrolyzed chemically (acid hydrolysis) and obtained product Locust Peptone (LP). The contents of protein, fat, nitrogen, ash, minerals, total sugars and amino acids of LP were determined and it was seen that it has both organic and inorganic materials enough to use as a component of the medium. The effects of different concentrations added 20g/l glucose of LP on the growth of four test bacteria (Escherichia coli, Bacillus subtilis, Pseudomonas putida and Staphylococcus aureus) and test yeasts (Rhodotorula glutinis, Candida albicans, Saccharomyces cerevisiae) were investigated and it was found that the optimal concentration for bacteria and yeast are %0,6 and LP was compared with bacteriological peptone (BP), fish peptone (FP) and meat peptone (MP) .The obtained results with surface streaking and shaking culture procedures showed that LP yielded a little higher or equal FP and BP in both normal bacteria, but these values were lower than values obtained from MP. The results show that LP performed similar to or even better than commercial peptones as nitrogen sources for microorganisms growth. A new peptone has been developed from locust for microbiological media in the present study.

Escherichia coli Can Eat DNA as an Excellent Nitrogen Source to Grow Quickly.

Is DNA or RNA a good nutrient? Although scientists have raised this question for dozens of years, few textbooks mention the nutritional role of nucleic acids. Paradoxically, mononucleotides are widely added to infant formula milk and animal feed. Interestingly, competent bacteria can bind and ingest extracellular DNA and even integrate it into their genome. These results prompt us to clarify whether bacteria can “eat” DNA as food. We found that Escherichia coli can grow well in the medium with DNA as carbon and nitrogen sources. More interestingly, in the presence of glucose and DNA, bacteria grew more rapidly, showing that bacteria can use DNA as an excellent nitrogen source. Surprisingly, the amount of DNA in the culture media decreased but its length remained unchanged, demonstrating that E. coli ingested long DNA directly. The gene expression study shows that E. coli mainly ingests DNA before digestion and digests it in the periplasm. Bifidobacterium bifidum can also use DNA as the nitrogen source for growth, but not efficiently as E. coli. This study is of great significance to study DNA metabolism and utilization in organisms. It also lays a foundation to understand the nutritional function of DNA in intestinal flora and human health.

Structural characterization of the urease accessory protein UreF from Klebsiella pneumoniae.

Klebsiella pneumoniae is an opportunistic pathogen that mostly affects those with weakened immune systems. Urease is a vital enzyme that can hydrolyze urea to ammonia and carbon dioxide as a source of nitrogen for growth. Urease is also a K. pneumoniae virulence factor that enables survival of the bacterium under nutrient-limiting conditions. UreF, an important nickel-binding urease accessory protein, is involved in the insertion of Ni2+ into the active site of urease. Here, the crystal structure of UreF from K. pneumoniae (KpUreF) is reported. Functional data show that KpUreF forms a stable dimer in solution. These results may provide a starting point for the design of urease inhibitors.

A glutamate synthase mutant of Bradyrhizobium sp. strain ORS285 is unable to induce nodules on Nod factor-independent Aeschynomene species

The Bradyrhizobium sp. strain ORS285 is able to establish a nitrogen-fixing symbiosis with both Nod factor (NF) dependent and NF-independent Aeschynomene species. Here, we have studied the growth characteristics and symbiotic interaction of a glutamate synthase (GOGAT; gltD::Tn5) mutant of Bradyrhizobium ORS285. We show that the ORS285 gltD::Tn5 mutant is unable to use ammonium, nitrate and many amino acids as nitrogen source for growth and is unable to fix nitrogen under free-living conditions. Moreover, on several nitrogen sources, the growth rate of the gltB::Tn5 mutant was faster and/or the production of the carotenoid spirilloxanthin was much higher as compared to the wild-type strain. The absence of GOGAT activity has a drastic impact on the symbiotic interaction with NF-independent Aeschynomene species. With these species, inoculation with the ORS285 gltD::Tn5 mutant does not result in the formation of nodules. In contrast, the ORS285 gltD::Tn5 mutant is capable to induce nodules on NF-dependent Aeschynomene species, but these nodules were ineffective for nitrogen fixation. Interestingly, in NF-dependent and NF-independent Aeschynomene species inoculation with the ORS285 gltD::Tn5 mutant results in browning of the plant tissue at the site of the infection suggesting that the mutant bacteria induce plant defence responses.

Catabolic characterization of dipicolinic acid in Alcaligenes faecalis strain JQ135

Dipicolinic acid (DPA) is a widely distributed pyridine derivative containing two carboxylate groups. However, the catabolism of DPA mediated by microorganisms are rarely reported. Alcaligenes faecalis strain JQ135, previously isolated in our lab, was able to degrade various pyridine derivatives, including nicotinic acid (NA). In this study, it was found that strain JQ135 could utilize DPA as the sole carbon and nitrogen source for growth and degrade 1.8 mM (300 mg/L) DPA to a non-detectable level within 12 h. The catabolism of DPA by strain JQ135 extracted two intermediates, i.e., 3-hydroxy-2,6-dipicolinic acid and 4-imino-pent-2-enedioic acid. Moreover, deletion of the key genes essential for NA catabolism (such as moaCDEBmoeA and maiA) did not affect DPA catabolism, indicating that the maleamate pathway and molybdenum cofactor are not involved in the DPA catabolism by strain JQ135. This study will provide insights into the bacterial catabolism of DPA.

Breast milk urea as a nitrogen source for urease positive Bifidobacterium infantis.

ABSTRACTHuman milk stimulates a health-promoting gut microbiome in infants. However, it is unclear how the microbiota salvages and processes its required nitrogen from breast milk. Human milk nitrogen sources such as urea could contribute to the composition of this early life microbiome. Urea is abundant in human milk, representing a large part of the non-protein nitrogen (NPN). We found that B. longum subsp. infantis (ATCC17930) can use urea as a main source of nitrogen for growth in synthetic medium and enzyme activity was induced by the presence of urea in the medium. We furthermore confirmed the expression of both urease protein subunits and accessory proteins of B. longum subsp. infantis through proteomics. To the same end, metagenome data were mined for urease-related genes. It was found that the breastfed infant's microbiome possessed more urease-related genes than formula fed infants (51.4:22.1; 2.3-fold increase). Bifidobacteria provided a total of 106 of urease subunit alpha alignments, found only in breastfed infants. These experiments show how an important gut commensal that colonizes the infant intestine can metabolize urea. The results presented herein further indicate how dietary nitrogen can determine bacterial metabolism in the neonate gut and shape the overall microbiome.

A 2‐Tyr‐1‐carboxylate Mononuclear Iron Center Forms the Active Site of a Paracoccus Dimethylformamidase

N,N‐dimethyl formamide (DMF) is an extensively used organic solvent but is also a potent pollutant. Certain bacterial species from genera such as Paracoccus, Pseudomonas, and Alcaligenes have evolved to use DMF as a sole carbon and nitrogen source for growth via degradation by a dimethylformamidase (DMFase). We show that DMFase from Paracoccus sp. strain DMF is a halophilic and thermostable enzyme comprising a multimeric complex of the α2β2 or (α2β2)2 type. One of the three domains of the large subunit and the small subunit are hitherto undescribed protein folds of unknown evolutionary origin. The active site consists of a mononuclear iron coordinated by two Tyr side‐chain phenolates and one carboxylate from Glu. The Fe3+ ion in the active site catalyzes the hydrolytic cleavage of the amide bond in DMF. Kinetic characterization reveals that the enzyme shows cooperativity between subunits, and mutagenesis and structural data provide clues to the catalytic mechanism.

Gimesia chilikensis sp. nov., a haloalkali-tolerant planctomycete isolated from Chilika lagoon and emended description of the genus Gimesia.

A Gram-stain-negative, aerobic, non-motile, salt- and alkali-tolerant, pear to oval shaped, rosette-forming, white coloured, bacterium, designated as strain JC646T, was isolated from a sediment sample collected from Chilika lagoon, India. Strain JC646T reproduced through budding, grew well at up to pH 9.0 and tolerated up to 7 % NaCl. Strain JC 646T utilized α-d-glucose, fumarate, lactose, sucrose, fructose, d-galactose, mannose, maltose and d-xylose as carbon sources. Peptone, l-isoleucine, l-serine, l-lysine, l-glutamic acid, l-aspartic acid, dl-threonine and l-glycine were used by the strain as nitrogen sources for growth. The respiratory quinone was MK6. Major fatty acids were C16 : 1 ω7c/C16 : 1 ω6c and C16 : 0. The polar lipids of strain JC646T comprised phosphatidyl-dimethylethanolamine, phosphatidylcholine, diphosphatidylglycerol, an unidentified amino lipid and two unidentified lipids. Strain JC646T had highest (97.3 %) 16S rRNA gene sequence identity to the only species of the genus Gimesia, Gimesia maris DSM 8797T. The genome of strain JC646T was 7.64 Mbp with a DNA G+C content of 53.2 mol%. For the resolution of the phylogenetic congruence of the novel strain, the phylogeny was also reconstructed with the sequences of 92 housekeeping genes. Based on phylogenetic analyses, digital DNA-DNA hybridization (19.0 %), genome average nucleotide identity (74.5 %) and average amino acid identity/percentageof conserved proteins (77 %) results, chemotaxonomic characteristics, and differential physiological properties, strain JC646T is recognized as representing a new species of the genus Gimesia, for which we propose the name Gimesia chilikensis sp. nov. The type strain is JC646T (=KCTC 72175T=NBRC 113881T).

Quinoline biodegradation characteristics of a new quinoline‐degrading strain, Pseudomonas citronellolis PY1

AbstractBACKGROUNDQuinoline exerts inhibitory effects on microorganisms in the biological process. However, microbial degradation of quinoline is feasible, and bacteria with quinoline‐degrading ability have gained increasing attention, making it possible to improve the bioremediation performance of wastewater. Therefore, this article focused on the quinoline removal performance of a new strain Pseudomonas citronellolis PY1.RESULTSThe optimal conditions of strain PY1 for quinoline removal are incubation temperature 30 °C, dissolved oxygen (DO) 4.69 mg/L and pH 7.0–9.0. For strain PY1, complete removal of quinoline could be achieved within 18 h. Zinc ions (Zn2+) have less toxicity to PY1 than cadmium ions (Cd2+), and efficient removal of quinoline occurs within 50 mg/L Zn2+ and 30 mg/L Cd2+. Through high‐performance liquid chromatography mass spectrometry (HPLC‐MS) analysis, five major intermediates were identified in the quinoline biodegradation process. On the basis of these intermediates and gas detection, strain PY1 is suggested to degrade quinoline through the typical 8‐hydroxy coumarin pathway.CONCLUSIONStrain PY1 could utilize quinoline as the sole carbon and nitrogen source for growth, and show superior quinoline biodegradation performance, as indicated by simultaneous biomass growth and high chemical oxygen demand (COD) removal accompanied with quinoline removal. All the results provide a theoretical base for treating actual wastewater containing quinoline. © 2020 Society of Chemical Industry

Using of Some Agro-industrial Wastes for Improving Carotenoids Production from Yeast Rhodotorula glutinis 32 and Bacteria Erwinia uredovora DSMZ 30080

Some agro-industrial wastes such as clarified cane molasses, high test molasses, sweet whey, potato starch and corn steep liquor were tested as carbon sources or nitrogen source for growth and carotenoid accumulation using bacteria Erwinia uredovora DSMZ 30080 and yeast Rhodotorula glutinis number 32. Erlenmeyer flasks containing 100 ml of production media, the flasks were inoculated with 1 ml of standard inoculum and incubated at 150 rpm for 4 days at 30°C. Samples were collected periodical every 24h, cell dry weight and carotenoids concentration were determined. Sweet whey and highest molasses gave the highest growth being 2.85 and 7.34 gl-1, respectively and scored the same layout on carotenoids conc. which reach the peak during stationary phase (72 h of fermentation). Using of high test molasses and sweet whey as carotenoid production media were incremented carotenoid conc. about 1.7 and 2 fold (with respect to reference media). Increasing high test molasses conc. to give 5% initial sugar led to up great growth, carotenoids conc., productivity, yield and Yc/x from Rhodo. glutinis 32 to be 7.31 gl-1, 2.67 mgl-1, 0.037 mgl-1h-1, 0.067% and 0.365, respectively. Furthermore, using corn steep liquor (30%) as nitrogen sources augmented carotenoids concentration about 3.8 and 4fold for incomplete and complete production media using Rhodo. glutinis32. Also, a negligible effect on growth was observed with dark incubation with both strains which dropped about 75 and 48% with regard to control for E. uredovora DSMZ 30080 and Rhod. glutinis 32, respectively, whereas, carotenoids conc. was increased about 21% for E. uredovora DSMZ 30080 in dark condition.

Biodegradation kinetics of microcystins-LR crude extract by Lysinibacillus boronitolerans strain CQ5

As the most common variant of microcystins (MCs), microcystin-LR (MCLR) is a kind of toxins produced by some species of harmful cyanobacteria and more and more attention has been paid to it. Biodegradation has been extensively investigated and recognized to be a cost-efficient and environmentally benign method for MC clean-up. In order to further research the growth characteristics of strain and the biodegradation characteristics of MCLR, it is necessary to use the dynamic mathematical models as powerful and useful tools. In this study, strain CQ5 was screened and identified by morphological observation, physiological and biochemical tests, and 16S rDNA sequence analysis. The kinetic models of cell growth and MCLR degradation were established with the Gompertz model and revised Monod kinetic model. The results showed that strain CQ5 had the closest phylogenetic similarity to Lysinibacillus boronitolerans (T-10a, AB199591) in the phylogenetic tree, with 99% bootstrap support. Strain CQ5 could utilize MCLR as the carbon and nitrogen source for growth. When the initial pH value was 7 and the inoculation amount was 3%, strain CQ5 grew well in MSM, in which the MCLR crude extract was used as the carbon and nitrogen source of strain CQ5. Within 244 h, the MCLR concentration changed from 14.12 to 1.57 μg/L and its degradation rate could reach 88.88%. The growth curve fitted with the Gompertz growth model (Nt = 1.3119 * exp(−0.1237 * exp(−6.6341t)), R2 > 0.99). The process of MCLR degradation agreed with the first-order reaction kinetic equation (lnS = 2.64764 − 0.01537t, R2 > 0.99). The linkage relationship between MCLR concentration, cell density, and MCLR degradation rate was consistent with the revised Monod equation (V = 0.342S, R2 > 0.97) at low substrate concentration, where Vmax/ Ks was 0.342. The dynamic relationship in which strain CQ5 degraded MCLR and used it as the carbon and nitrogen source to promote its own growth could be explained by the equation S = 14.12 e− 0.342 Nt (N = 1.08). The growth of strain CQ5 and MCLR concentration in degradation system could be simulated and predicted by the dynamic mathematical models in this study. And the predicted results were very consistent. These results could provide theoretical reference for studying the mechanism of MCLR biodegradation and promote the engineering application of strain CQ5.