Inorganic Nitrogen Sources Research Articles

Effect of Nitrogen on in Vitro Propagation of Endangered Medicinal Plant: Swertia Chirayita Roxb. Ex Flaming

The effect of nitrogen was investigated on the organogenesis of Swertia chirayita (Gentianaceae) to overcome the challenges related to its cultivation. The best callogenic response was observed on root explants inoculated onto MS medium supplemented with BAP (2.0 mg/l) along with 2,4-D (0.5 mg/l) after 35 days of culture. Subsequent transfer of callus for multiplication on the same media composition under complete darkness presents the best results in terms of callus multiplication. Callogenic cultures were subculture onto modified MS medium supplemented with inorganic nitrogen sources, i.e., NH4NO3 (14-56N/l), KNO3 (100-400N/l) with BAP (3.0 mg/l) were observed. Organogenic response (52%) was observed after 8-12 weeks of culturing. The maximum number of the shoot was recorded on MS medium with NH4NO3 (28 N/l), KNO3 (300N/l) with BAP (3.0 mg/l). Moreover, 90% of them were able to regrow when sub-cultured on the same media. Sixteen weeks old multiple shoots were subcultured on MS medium supplemented with different auxins. IAA was proved to be the best hormone rooting purpose. However, the best rooting response regarding the number of roots and an average length of roots was obtained at IAA (1.0 mg/l). Survival of 90% was achieved when rooted plantlets were successfully established in substrate containing sand, vermicompost, and garden soil in equal proportion for hardening and acclimatized.

Perpetual atmospheric dry deposition exacerbates the unbalance of dissolved inorganic nitrogen and phosphorus in coastal waters: A case study on a mariculture site in North China

The monthly magnitudes of dissolvable nutrients through atmospheric dry deposition (ADD) and their ecological effects to the coastal waters around the Yangma Island, North Yellow Sea, were investigated for one year. The results indicated that anthropogenic activities were the major sources of dissolvable inorganic and organic nitrogen (DIN and DON); dust events were the major sources of inorganic phosphorus (DIP) and silicate (DSi); however, organic phosphorus (DOP) could be originated from marine biological activities. The annual ADD fluxes of DIN, DON, DIP, DOP and DSi were 21.8, 2.7, 0.10, 0.30 and 0.73 mmol m−2 yr−1, respectively. Overall, the new production supported by the bioavailable nitrogen through ADD in winter was up to 9.14 mg C m−2 d−1. Notably, the annual molar ratio of DIN/DIP through ADD was 216 ± 123, which was much higher than that of the dissolved inorganic nitrogen to phosphorus in seawater and might exacerbate their unbalance in some coastal waters.

Effect of Organic and Inorganic Sources of Nitrogen on Growth, Yield, and Quality of Beetroot Varieties in Nepal

Economic use of organic and inorganic fertilizers following their availability is necessary for livestock-based Nepalese farming systems. However, how best to integrate these fertilizers in an appropriate manner is not yet clear. Thus, this study was conducted in the horticulture farm of the Agriculture and Forestry University (AFU), Rampur, Chitwan, Nepal from November 2018 to February 2019 to evaluate the effect of organic and inorganic sources of nitrogen (N) on growth, yield, and quality of beetroot (Beta vulgaris L.) varieties. The experiment was laid out in a two factorial randomized complete block design with four replications consisting of two beetroot varieties, i.e., Madhur and Ruby Red, and five N source combinations, i.e., N1: 100% poultry manure (PM), N2: 50% PM + 50% urea, N3: 100% farmyard manure (FYM), N4: 50% FYM + 50% urea, and N5: 100% urea (120:80:40 kg NPK ha−1). Results of this study indicated a significant impact of N sources and varieties on the assessed parameters. During harvest, a significantly higher plant height (41.84 cm), number of leaves per plant (14.68), leaf length (34.56 cm), leaf width (11.38 cm), and beetroot diameter (72.15 mm) were observed in the N2 treatment. Likewise, higher economic (49.78 t ha−1) and biological yields (78.69 t ha−1) were also recorded in the N2 compared to other N sources. Out of the two varieties, the Madhur variety was significantly better in most growth and yield parameters. Similarly, the Madhur variety showed a significantly higher economic (44.49 t ha−1) and biological yields (69.79 t ha−1) compared to the Ruby Red variety. However, the physiological weight loss was higher in the Ruby Red variety. Therefore, the current study suggests that an integration of poultry manure along with the combination of N fertilizer and the Madhur variety is the best combination for quality beetroot production in the Terai region of Nepal.

Biodegradation of P-nitro phenol using a novel bacterium Achromobacter denitrifacians isolated from industrial effluent water.

In the present investigation, Achromobacter denitrifacians was isolated from industrial wastewater and used in the degradation of para nitro-phenol. Experiments were made as a function of different carbon sources, organic and inorganic nitrogen sources and metal ions to analyse the removal efficiency of para nitro-phenol present in the industrial wastewater sources. Observations revealed that the rate of phenol biodegradation was significantly affected by pH, temperature of incubation, glucose, peptone and metal ion concentration. The optimal conditions for phenol removal were found to be pH of 7.5, temperature, 35 °C and 0.25 gL-1 supplemented glucose level, 0.25 gL-1 supplemented peptone level, and 0.01 gL-1 zinc ion. The key importance of the present study is the utilization of a native bacterial strain isolated from the industrial effluent water itself having an impending role in the bioremediation process of phenol.

Understanding working conditions for Entererococcus sp. L1 on methane production: A low temperature condition-based biogas production experiment

To provide an elaborate understanding on the performance of Entererococcus sp. L1 in biogas production at different fermentation periods under controlled low temperature, biogas optimization experiments was undertaken. Specifically, microscopic and culture techniques, physiological and biochemical studies, and measurement of optical densities at 600 wavelengths (OD600) were undertaken to identify and characterize the Entererococcus sp. L1. The aim was to identify the strain and determine its optimum working conditions in biogas production at different fermentation periods under controlled low temperature. The result confirmed the strain as hydrogen-producing bacteria (Enteroccus sp. L1). It was also confirmed that the organic nitrogen source was significantly better than the inorganic nitrogen source in supporting the growth of the bacteria. The optimal pH and temperature for the growth and biogas production performance of the Entererococcus sp. L1 was 7 and 15 °C respectively. The Na2HPO4 concentration of 0.2% was confirmed to be best for the optimum growth of the bacteria, and addition of citric acid resulted to significant inhibitory effect on the growth of the Entererococcus sp. L1. The effect of adding different concentrations (0, 1%, 5%, 10%) of the L1 bacteria inoculum on cow dung at simulated low temperature (15 °C) biogas fermentation showed that 10% treatment had the highest gas production of 3121 ml, which was 89% higher than the control (0 concentration). The daily gas production rate was 0.02 m3/(m−3d−1), which was 90% higher than the control. This showed that 10% treatment provided the best gas production result, with highest gas production occurring at 10% treatment within 31–60 days of fermentation (p < 0.05). The study therefore recommends application of the Entererococcus sp. L1 in biogas production under the above confirmed optimum working conditions for increased bigas quality and quantity.

Inorganic and organic carbon and nitrogen uptake strategies of picoplankton groups in the northwestern Atlantic Ocean

AbstractPicoplankton populations dominate the planktonic community in the surface oligotrophic ocean. Yet, their strategies in the acquisition and the partitioning of organic and inorganic sources of nitrogen (N) and carbon (C) are poorly described. Here, we measured at the single‐cell level the uptake of dissolved inorganic C (C‐fixation), C‐leucine, N‐leucine, nitrate (NO3−), ammonium (NH4+), and N‐urea in pigmented and nonpigmented picoplankton groups at six low‐N stations in the northwestern Atlantic Ocean. Our study highlights important differences in trophic strategies between Prochlorococcus, Synechococcus, photosynthetic pico‐eukaryotes, and nonpigmented prokaryotes. Nonpigmented prokaryotes were characterized by high leucine uptake rates, nonsignificant C‐fixation and relatively low NH4+, N‐urea, and NO3− uptake rates. Nonpigmented prokaryotes contributed to 7% ± 3%, 2% ± 2%, and 9% ± 5% of the NH4+, NO3−, and N‐urea community uptake, respectively. In contrast, pigmented groups displayed relatively high C‐fixation rates, NH4+ and N‐urea uptake rates, but lower leucine uptake rates than nonpigmented prokaryotes. Synechococcus and photosynthetic pico‐eukaryotes NO3− uptake rates were higher than Prochlorococcus ones. Pico‐sized pigmented groups accounted for a significant fraction of the community C‐fixation (63% ± 27%), NH4+ uptake (47% ± 27%), NO3− uptake (62% ± 49%), and N‐urea uptake (81% ± 35%). Interestingly, Prochlorococcus and photosynthetic pico‐eukaryotes showed a greater reliance on C‐ and N‐leucine than Synechococcus on average, suggesting a greater reliance on organic C and N sources. Taken together, our single‐cell results decipher the wide diversity of C and N trophic strategies between and within marine picoplankton groups, but a clear partitioning between pigmented and nonpigmented groups still remains.

Impact of Nitrate and Ammonium Concentrations on Co-Culturing of Tetradesmus obliquus IS2 with Variovorax paradoxus IS1 as Revealed by Phenotypic Responses.

Mutual interactions in co-cultures of microalgae and bacteria are well known for establishing consortia and nutrient uptake in aquatic habitats, but the phenotypic changes in terms of morphological, physiological, and biochemical attributes that drive these interactions have not been clearly understood. In this novel study, we demonstrated the phenotypic response in a co-culture involving a microalga, Tetradesmus obliquus IS2, and a bacterium, Variovorax paradoxus IS1, grown with varying concentrations of two inorganic nitrogen sources. Modified Bold's basal medium was supplemented with five ratios (%) of NO3-N:NH4-N (100:0, 75:25, 50:50, 25:75, and 0:100), and by maintaining N:P Redfield ratio of 16:1. The observed morphological changes in microalga included an increase in granularity and a broad range of cell sizes under the influence of increased ammonium levels. Co-culturing in presence of NO3-N alone or combination with NH4-N up to equimolar concentrations resulted in complete nitrogen uptake, increased growth in both the microbial strains, and enhanced accumulation of carbohydrates, proteins, and lipids. Total chlorophyll content in microalga was also significantly higher when it was grown as a co-culture with NO3-N and NH4-N up to a ratio of 50:50. Significant upregulation in the synthesis of amino acids and sugars and downregulation of organic acids were evident with higher ammonium uptake in the co-culture, indicating the regulation of carbon and nitrogen assimilation pathways and energy synthesis. Our data suggest that the co-culture of strains IS1 and IS2 could be exploited for effluent treatment by considering the concentrations of inorganic sources, particularly ammonium, in the wastewaters.

Transcriptome Variations in Verticillium dahliae in Response to Two Different Inorganic Nitrogen Sources.

The fungus Verticillium dahliae causes vascular wilt disease on hundreds of plant species. The main focus of the research to control this fungus has been aimed at infection processes such as penetration peg formation and effector secretion, but the ability of the fungus to acquire and utilize nutrients are often overlooked and may hold additional potential to formulate new disease control approaches. Little is known about the molecular mechanisms of nitrogen acquisition and assimilation processes in V. dahliae. In this present study, RNA sequencing and gene expression analysis were used to examine differentially expressed genes in response to the different nitrogen sources, nitrate and ammonium, in V. dahliae. A total of 3244 and 2528 differentially expressed genes were identified in response to nitrate and ammonium treatments, respectively. The data indicated nitrate metabolism requires additional energy input while ammonium metabolism is accompanied by reductions in particular cellular processes. Gene ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses of DEGs during nitrate metabolism revealed that many of the genes encoded those involved in protein biosynthetic and metabolic processes, especially ribosome and RNA polymerase biosynthesis, but also other processes including transport and organonitrogen compound metabolism. Analysis of DEGs in the ammonium treatment indicated that cell cycle, oxidoreductase, and certain metabolic activities were reduced. In addition, DEGs participating in the utilization of both nitrate and ammonium were related to L-serine biosynthesis, energy-dependent multidrug efflux pump activity, and glycerol transport. We further showed that the mutants of three differentially expressed transcription factors (VdMcm1, VdHapX, and VDAG_08640) exhibited abnormal phenotypes under nitrate and ammonium treatment compared with the wild type strain. Deletion of VdMcm1 displayed slower growth when utilizing both nitrogen sources, while deletion of VdHapX and VDAG_08640 only affected nitrate metabolism, inferring that nitrogen assimilation required regulation of bZIP transcription factor family and participation of cell cycle. Taken together, our findings illustrate the convergent and distinctive regulatory mechanisms between preferred (ammonium) and alternative nitrogen (nitrate) metabolism at the transcriptome level, leading to better understanding of inorganic nitrogen metabolism in V. dahliae.

Genome-wide survey and expression analysis of NIN-like Protein (NLP) genes reveals its potential roles in the response to nitrate signaling in tomato

BackgroundTomato (Solanum lycopersicum) is one of the most important horticultural crops, with a marked preference for nitrate as an inorganic nitrogen source. The molecular mechanisms of nitrate uptake and assimilation are poorly understood in tomato. NIN-like proteins (NLPs) are conserved, plant-specific transcription factors that play crucial roles in nitrate signaling.ResultsIn this study, genome-wide analysis identified six NLP members in tomato genome. These members were clustered into three clades in a phylogenetic tree. Comparative genomic analysis showed that SlNLP genes exhibited collinear relationships to NLPs in Arabidopsis, canola, maize and rice, and that the expansion of the SlNLP family mainly resulted from segmental duplications in the tomato genome. Tissue-specific expression analysis showed that one of the close homologs of AtNLP6/7, SlNLP3, was strongly expressed in roots during both the seedling and flowering stages, that SlNLP4 and SlNLP6 exhibited preferential expression in stems and leaves and that SlNLP6 was expressed at high levels in fruits. Furthermore, the nitrate uptake in tomato roots and the expression patterns of SlNLP genes were measured under nitrogen deficiency and nitrate resupply conditions. Four SlNLPs, SlNLP1, SlNLP2, SlNLP4 and SlNLP6, were upregulated after nitrogen starvation. And SlNLP1 and SlNLP5 were induced rapidly and temporally by nitrate.ConclusionsThese results provide significant insights into the potential diverse functions of SlNLPs to regulate nitrate uptake.

&lt;p&gt;&lt;strong&gt;Statistical optimization of alkaline protease from &lt;em&gt;Bacillus amyloliquefaciens &lt;/em&gt;SP1&lt;/strong&gt;&lt;/p&gt;

Alkaline protease has tremendous applications in different industries, and to fulfil industrial and commercial enzyme requirements, overproduction and optimization of production medium are prerequisites. Protease production by Bacillus amyloliquefaciens SP1, isolated from apple tree rhizosphere was studied. Plackett Burmann design and response surface methodology was used to optimize medium for alkaline protease production. Higher levels of protease activity were observed in presence of disaccharides owing to diauxic growth and inorganic nitrogen sources proved to be less favourable. After screening through one-factor-at-a time experiments and Plackett Burmann design, casein, yeast extract, maltose and KH2PO4 were identified as the most significant variables. Statistical design based three-dimensional (3-D) and contour plots were generated to understand the relationship between enzyme activity and medium variables. The protease production was found to increase from 1730 to 3630 µg/ml/min in optimized medium i.e. approx. 2.1 fold increased compared with original medium. The study assumes significance in the ability of bacterium to survive in wide variety of salts and agricultural wastes and yield optimum levels of extracellular protease.

Sources and transformation mechanisms of inorganic nitrogen: Evidence from multi-isotopes in a rural-urban river area

Multi-isotope tracers were applied to quantitatively reveal the sources and transformation mechanisms of inorganic nitrogen both spatially and seasonally in a complex land use area in China. Based on land use and the level of socioeconomic development, the study area was divided into four zones: the rural area, developed urban area, developing urban area and industrial urban area. The redox condition and isotope analysis results indicated that the nitrification process dominated in the Han and Rong River, which were characterized by ammonium nitrogen (NH4+-N) and oxidizing conditions, while neither nitrification nor denitrification occurred in the Lian River. The inorganic nitrogen sources of the four areas were revealed from the results of a stable isotope analysis in R (SIAR) and a two-component mixing model after determining the transformation mechanisms. In the rural area, nitrate nitrogen (NO3−-N) was mainly sourced from the increased fertilization of nitrogen fertilizer (42–56%) to farmland during the wet season, and from soil nitrogen (33–62%) related to increased nitrification during the dry season. In the urban area, the contributions of soil nitrogen, manure and sewage and industrial wastewater to the total inorganic nitrogen exhibited large seasonal and spatial differences, which were distinguished by the environmental management supported by gross domestic production (GDP). In the developed and developing urban areas, soil nitrogen contributed 41% and 47% of the NO3−-N, respectively, during the wet season, and 47% and 54%, respectively, during the dry season. The second highest contribution was from manure and sewage (30–41%) with no seasonal differences. In the industrial urban area, the dominant contribution to the NH4+-N was from manure and sewage (81%) during the wet season, but industrial wastewater (84%) in the dry season. Our findings elucidate the multiplex sources and transformation mechanisms of inorganic nitrogen, and promote the management of nitrogen tracing to control nitrogen pollution in complex land use areas.

Evaluation of temperature, pH and nutrient conditions in bacterial growth and extracellular hydrolytic activities of two Alicyclobacillus spp. strains

Extremophile bacteria have developed the metabolic machinery for living in extreme temperatures, pH, and high-salt content. Two novel bacterium strains Alicyclobacillus sp. PA1 and Alicyclobacillus sp. PA2, were isolated from crater lake El Chichon in Chiapas, Mexico. Phylogenetic tree analysis based on the 16SrRNA gene sequence revealed that the strain Alicyclobacillus sp. PA1 and Alicyclobacillus sp. PA2 were closely related to Alicyclobacillus species (98% identity and 94.73% identity, respectively). Both strains were Gram variable, and colonies were circular, smooth and creamy. Electron microscopy showed than Alicyclobacillus sp. PA1 has a daisy-like form and Alicyclobacillus sp. PA2 is a regular rod. Both strains can use diverse carbohydrates and triglycerides as carbon source and they also can use organic and inorganic nitrogen source. But, the two strains can grow without any carbon or nitrogen sources in the culture medium. Temperature, pH and nutrition condition affect bacterial growth. Maximum growth was produced at 65°C for Alicyclobacillus sp. PA1 (0.732 DO600) at pH 3 and Alicyclobacillus sp. PA2 (0.725 DO600) at pH 5. Inducible extracellular extremozyme activities were determined for β-galactosidase (Alicyclobacillus sp. PA1: 88.07 ± 0.252 U/mg, Alicyclobacillus sp. PA2: 51.57 ± 0.308 U/mg), cellulose (Alicyclobacillus sp. PA1: 141.20 ± 0.585 U/mg, Alicyclobacillus sp. PA2: 51.57 ± 0.308 U/mg), lipase (Alicyclobacillus sp. PA1: 138.25 ± 0.600 U/mg, Alicyclobacillus sp. PA2: 175.75 ± 1.387 U/mg), xylanase (Alicyclobacillus sp. PA1: 174.72 ± 1.746 U/mg, Alicyclobacillus sp. PA2: 172.69 ± 0.855U/mg), and protease (Alicyclobacillus sp. PA1: 15.12 ± 0.121 U/mg, Alicyclobacillus sp. PA2: 15.33 ± 0.284 U/mg). These results provide new insights on extreme enzymatic production on Alicyclobacillus species.

Optimization of α‐amylase and Glucoamylase Production Using Cull Potatoes as Substrate

AbstractAmylases are required for the conversion of starchy substrate into sugars. Commercially available enzymes are quite costly which makes the process uneconomical. This study is conducted to standardize physico‐chemical parameters such as substrate concentration (1.0–5.0%), temperature (25–40 °C), pH (4.0–7.0), incubation time (18–24) h for α‐amylase and 3–6 days for glucoamylase production) for optimum production of α‐amylase from bacterial isolate (AM1) and glucoamylase from Aspergillus niger by using cull potatoes as a substrate. Various organic and inorganic nitrogen sources (urea, yeast extract and soybean meal, and ammonium sulphate) are tried for maximum enzyme production. Among the four nitrogen sources, yeast extract supported maximum α‐amylase and glucoamylase production. Among the different amylolytic isolates from fermented jalebi dough and AM1culture, maximum α‐amylase activity is shown by AM1 (90.46 U mL−1) as compared to J1 (71.02 U mL−1). After optimization, α‐amylase activity of AM1 increases by 41.73% from 198.20 to 280.92 U mL−1 at 5.0% substrate concentration, 30 °C temperature, 24 h of incubation and pH 5.0. Glucoamylase activity of A. niger increases by 38.78% from 228.72 to 317.44 U mL−1 after optimization at 5% substrate concentration, pH 5, incubation period of 4 days and temperature 30 °C.

Production and stability of pigments by Talaromyces purpurogenus LC128689 in an alternating air phase-liquid phase cultivation system.

Effects of carbon source, nitrogen source, and alternatingly submerging the cells and exposing to gaseous oxygen on pigment production by Talaromyces purpurogenus LC128689, as well as pH, temperature, and UV stability of the pigments were investigated. Although fructose supported higher cell growth, a mixture of glucose and glycerol resulted in higher pigment production. Out of the organic and inorganic nitrogen sources investigated, peptone gave the highest cell concentration (7.2 ± 1.1g/L) and pigment production (p≤0 .05). The cells were then immobilized in loofa sponge and cultivated under alternating liquid phase-air phase (ALAP) system whereby the cells were alternatingly submerged and exposed to gaseous oxygen. After 20 days of cultivation, the concentrations of the red, orange, and yellow pigments were 30.15 AU500 nm , 15 AU460nm , and 6.25 AU400 nm , respectively. In comparison with submerged culture in flasks, the red and orange pigments were 100% and 50% higher (p≤0.05) in ALAP system. On the other hand, the yellow pigment was 100% higher in flask cultures than in ALAP. The three pigments were stable within a pH range of 2-12, retained more than 80% of their color intensity after autoclaving at (121°C and 1.0 atm) for 15min and exposure to UV (3uW/cm2 ) for 24h.

Does Nitrate Enrichment Accelerate Organic Matter Turnover in Subterranean Estuaries?

Due to the widespread pollution of coastal groundwaters with fertilizers, submarine groundwater discharge (SGD) is often thought to be a large dissolved inorganic nitrogen (DIN) source to the ocean. Whether this N is autochthonous or allochthonous to the subterranean estuary (STE), the availability of large quantities of DIN can nevertheless interact with the cycling of other elements, such as carbon (C). In previous studies, we documented the discharge of large quantities of freshwater and NO3– from the mouth of an STE into the Ria Formosa lagoon (SW Iberian Peninsula). For the period covered in this study (2009–2011), the same STE site was dominated by recirculating seawater due to a prolonged fall in piezometric head in the coupled coastal aquifers. Total SGD rates remained similarly high, peaking at 144 cm day–1 at the lower intertidal during fall. We observed a progressive increase of NO3– availability within the STE associated with the recovery of piezometric head inland. Interestingly, during this period, the highest SGD-derived dissolved organic C and DIN fluxes (112 ± 53 and 10 ± 3 mmol m–2 day–1, respectively) originated in the lower intertidal. NO3– enrichment in the STE influences the benthic reactivity of fluorescent dissolved organic matter (FDOM): when seawater recirculation drives STE dynamics, only small changes in the benthic distribution of recalcitrant humic-like FDOM are observed (from −2.57 ± 1.14 to 1.24 ± 0.19 10–3 R.U. “bulk” sediment h–1) in the absence of DIN. However, when DIN is available, these recalcitrant fractions of FDOM are actively generated (from 1.32 ± 0.15 to 11.56 ± 3.39 10–3 R.U. “bulk” sediment h–1), accompanied by the production of labile protein-like FDOM. The results agree with previous studies conducted with flow-through reactor experiments at the same site and suggest that DIN enrichment in the STE enhances the metabolic turnover of sedimentary organic matter up to the point of discharge to surface waters. DIN pollution of coastal aquifers may therefore promote a contraction of the residence time of particulate organic C within the STE, driving carbon from continental storage into the sea.

Influence of Nitrogen Sources on D-Lactic Acid Biosynthesis by Sporolactobacillus laevolacticus DSM 442 Strain

The purpose of this study was to explore the possibility of replacing an expensive yeast extract contained in the fermentation medium for D-lactic acid (D-LA, R-lactic acid) biosynthesis with an alternative nitrogen source. The screening studies were conducted under stationary conditions and showed that pea seed hydrolysate was the most beneficial substrate in the process of D-LA biosynthesis by the strain Sporolactobacillus laevolacticus DSM 442 among the used inorganic and organic nitrogen sources, waste materials, food and agricultural products. After 96 h, 75.5 g/L D-LA was obtained in batch cultures in a medium containing pea seed hydrolysate, with an average productivity of 0.79 g/L/h, yield of 75.5%, and optical purity of 99.4%. In batch cultures fed once, in a medium with an analogous composition, 122.6 g/L D-LA was obtained after 120 h, and the average yield, productivity and optical purity were 87.6%, 1.021 g/L/h, and 99.6%, respectively. Moreover, the amount of D-LA obtained in the fermentation medium enriched with the above-mentioned cheap agricultural product was similar to the amounts obtained in the medium containing yeast extract in both stationary and bioreactor cultures. Our research shows that hydrolyzed pea seeds, which belong to the legume family, may be a promising nitrogen source for the production of D-LA on an industrial scale.

Keratinolytic protease from Pseudomonas aeruginosa for leather skin processing

BackgroundThe leather industry generates huge volume of waste each year. Keratin is the principal constituents of this waste that is resistant to degradation. Some bacteria have the ability to degrade keratin through synthesis of a protease called keratinase that can be used as sources of animal feed and industrial production of biodiesel, biofertilizer, and bioplastic. Majority of the studies focused on keratin degradation using gram-positive bacteria. Not much of studies are currently available on production of keratinase from gram-negative bacteria and selection of best parameters for the maximum production of enzyme. The aim of this study was to isolate and characterize both groups of bacteria from soil for keratinase and optimize the production parameters. ResultsA total of 50 isolates were used for initial screening of enzyme production in skim milk, casein, and feather meal agar. Out of 50, five isolates showed significantly higher enzyme production in preliminary screening assays. Morphological and biochemical characterization revealed 60% of the isolates as gram-negative bacteria including two highest enzyme-producing isolates. The isolates were identified as Pseudomonas aeruginosa through sequencing of 16S rRNA gene. Maximum production of enzyme from P. aeruginosa YK17 was achieved with 2% chicken feather, beef extract, and ammonium nitrate as organic and inorganic nitrogen sources and glucose as a carbon source. Further analysis revealed that 3% inoculum, 40 °C growth temperature and 72-h incubation, resulted in maximum production of keratinase. ConclusionThe overall results showed significant higher production of enzyme by the P. aeruginosa YK17 that can be used for the degradation of recalcitrant keratin waste and chemical dehairing in leather industries, thereby preventing environmental pollution.

Optimization of Crude Oil Biodegradation by Brevibacterium sp. Isolated from the Native Sponges of the Persian Gulf.

Background: The native sponges of Persian Gulf are unique species facing difficult climate conditions and environmental contamination. It is necessary to investigate these native sponges because global warming most probably destroyed many of these creatures. Therefore, the study of the microorganisms associated with sponges will introduce new bacterial strains with various industrial and environmental applications and, in this way, a part of the Persian Gulf biodiversity will be preserved for posterity.Objective: The aim of this study was the isolation and molecular identification of bacteria associated with the ability of biodegrading crude oil from the native sponges of the Persian Gulf. Also, optimization of crude oil biodegradation was done for one of the most efficient bacterial strains.Materials and Methods: Isolated species were compared in terms of E24 index and growth rate in a culture medium containing at least 2% of oil as the sole carbon source. Molecular identification was done for five bacterial strains. Using the Taguchi experimental design, the effects of 4 factors, namely, carbon source auxiliary, organic and inorganic nitrogen sources, salinity and pH, were evaluated at 3 levels. GC-Mass analysis was performed on the remaining oil in the culture medium.Results: In the initial screening of two native species of sponges, 22 bacterial strains were isolated which were capable of decomposing oil. Five bacterial strains showed the best results and were recorded in NCBI with access numbers KY283126, KY283128, KY285290, KY285289, and KY285288. Brevibacterium sp. (KY283128) showed the highest level of oil degradation (about 97%) and growth rate. The results showed that the optimal oil degradation occurs in the absence of carbon source auxiliary, at 0.5% of salinity, with NH4Cl as the nitrogen source and at a pH of 6.5.Conclusions: This bacterial strain can be used for biodegradation in oil-contaminated areas and oil refineries. By isolating the oil degrading gene in this bacterial strain and cloning it in other bacterial strains, the efficiency of eliminating oil contamination can be increased.

Simultaneous high nutritional single cell oil and lipase production by Candida viswanathii.

Omega fatty acids are a family of polyunsaturated fats associated with several health benefits. Lipases are enzymes with potential application in several food processes such as flavor and aroma, surfactants and formulations for the dairy and bakery industries. In this study, single cell oil and lipase production by Candida viswanathii CCR8137 were evaluated simultaneously from renewable carbon sources under nitrogen limitation. Enzyme and single cell oil were obtained in submerged cultivations supplemented with triolein, tributyrin, corn oil, sunflower oil, canola oil and olive oil. The effects of glucose on lipid accumulation, fatty acid profile, enzyme production and cell morphology were also evaluated. The highest lipid accumulation (44.5%, w/w) was obtained from triolein, whereas olive oil was the best inducer of lipase synthesis (26.8 U/mL). Nitrogen limiting cultivations were a key parameter for an organic source which showed higher lipid accumulation and enzyme production than the tested inorganic nitrogen source. Glucose was a poor inducer of lipase synthesis, though increased values of lipid accumulation were observed from this carbon source with a maximum of 63.1% (w/w). The fatty acid profile of lipids produced by C. viswanathii CCR8137 showed a high content of omega-9 fatty acid (C18:1 n-9). The addition of glucose to the culture media resulted in the synthesis of essential fatty acids: vaccenic, linolenic and eicosadienoic acids. Therefore, C. viswanathii CCR8137 strain can be considered as an oleaginous yeast able to accumulate high concentrations of intracellular lipids, which are potential additives for food industry applications as well as being able to simultaneously synthesize high yields of lipase.

DNA affinity purification sequencing and transcriptional profiling reveal new aspects of nitrogen regulation in a filamentous fungus

Sensing available nutrients and efficiently utilizing them is a challenge common to all organisms. The model filamentous fungus Neurospora crassa is capable of utilizing a variety of inorganic and organic nitrogen sources. Nitrogen utilization in N. crassa is regulated by a network of pathway-specific transcription factors that activate genes necessary to utilize specific nitrogen sources in combination with nitrogen catabolite repression regulatory proteins. We identified an uncharacterized pathway-specific transcription factor, amn-1, that is required for utilization of the nonpreferred nitrogen sources proline, branched-chain amino acids, and aromatic amino acids. AMN-1 also plays a role in regulating genes involved in responding to the simple sugar mannose, suggesting an integration of nitrogen and carbon metabolism. The utilization of nonpreferred nitrogen sources, which require metabolic processing before being used as a nitrogen source, is also regulated by the nitrogen catabolite regulator NIT-2. Using RNA sequencing combined with DNA affinity purification sequencing, we performed a survey of the role of NIT-2 and the pathway-specific transcription factors NIT-4 and AMN-1 in directly regulating genes involved in nitrogen utilization. Although previous studies suggested promoter binding by both a pathway-specific transcription factor and NIT-2 may be necessary for activation of nitrogen-responsive genes, our data show that pathway-specific transcription factors regulate genes involved in the catabolism of specific nitrogen sources, while NIT-2 regulates genes involved in utilization of all nonpreferred nitrogen sources, such as nitrogen transporters. Together, these transcription factors form a nutrient sensing network that allows N. crassa cells to regulate nitrogen utilization.