Carbon To Nitrogen Ratio Research Articles

Critical water quality parameters and certain non specific immune parameters of Clarias gariepinus juveniles raised in bioflocs system with cassava flour and rice bran as carbon sources

This study was conducted to examine effects of bioflocs culture on critical water parameters and certain non specific immune parameters in C. gariepinus juveniles. This experiment was conducted for 72 days, in 9 separate tanks with an aerated blower. Bioflocs culture had two different sources of carbon addition. This research consists of three treatments, carbon sources were added at CN ratio of 15:1. Results showed no significant difference in dissolved oxygen, pH, and temperature in all treatments. However, conductivity, Total dissolved solids and salinity showed significant difference across all treatment groups. Total ammonia nitrogen, nitrate and nitrite showed significant difference between control and bioflocs treatments. Blood parameters examined were serum lysozyme, myeloperoxidase activity, neutrophils, lymphocytes and monocytes percentage. Serum lysozyme and myeloperoxidase showed significant difference across treatments while neutrophils percentage showed significant difference between bioflocs culture and control experiment. Lymphocytes and monocytes showed no significant difference.

Features of sewage sludge degradation being involved in biomethanogenesis

Recycling waste into biogas not only provides energy source material, but also reduces the concentration of organic matter in the recycled raw material. The paper studies energy potential and rate of sewage sludge digestion, once combined at municipal plants with chicken manure and sugar beet pulp. A laboratory biogas plant with batch reactors was used for trials. A specific yield of biogas from activated sludge was 597.97±154.75 ml/g OM, specific yield of methane – 9.93±3.16 ml/g OM. The rate of organic matter digestion was 19.31%. Adding broiler chicken manure and sugar beet pulp into the bioreactor had a positive effect on fermentation. The specific yield of biogas increased to 978.39±166.32, bagasse – up to 1089.12±195.26 ml/g OM. The specific yield of methane increased, respectively, to 44.75±12.9 and 16.24±8.16 ml/g OM. The organic matter degradation rate increased to 30.61%, bagasse – to 33.94%. Thus, chicken manure and sugar beet pulp added into the bioreactor increases the efficiency of sludge treated into biogas, which is most likely due to increased mass fraction of organic matter and normalized carbon-nitrogen ratio in the bioreactor.

Different carbon sources influences the growth and digestive enzyme activity of grey mullet (Mugil cephalus) in biofloc based nursery rearing system

Aim: To assess the impact of different carbon sources on growth performance of grey mullet, Mugil cephalus fry in biofloc based culture system during nursery rearing phase. Methodology: The experimental trial was carried out for 60 days using three carbon sources, cassava, jaggery and barley in triplicate following a Completely Randomized Design. The carbon nitrogen ratio (C:N) in the systems were maintained at 15:1. Grey mullet fry (0.91g) were stocked @ of 1 fry 10 l-1 and were fed with pelleted feed (35% crude protein) @ 4% of fish body weight thrice daily. Results: Significantly higher (P<0.05) growth performance, in terms of Specfic Growth Rate (3.78 % day-1) with lower Feed Conversion Ratio (1.35) were found in barley based biofloc group. Similarly, enhanced digestive enzyme activity in terms of amylase (8.78 Unit mg protein-1 min-1), lipase (2.77 Unit mg protein-1 min-1) and protease (4.22 Unit mg protein-1 min-1) were found in barley based biofloc group. Non- specific immune parameters such as lysozyme, respiratory burst activity and myeloperoxidase activity were significantly higher in barley based treatment group followed by jaggery and cassava based treatment groups. Likewise, stress indicators in serum and antioxidant status in liver were found to be lower in barley based treatment compared to cassava and jaggery based treatment groups. Interpretation: Rearing of Mugil cephalus in biofloc culture system is practicable; however, the carbon source required for biofloc production could be barley, compared to cassava and jaggery, in order to achieve maximum growth and to reduce the stress.

Comparing Rooting Ability and Physiological Changes of Two Eucommia ulmoides Improved Varieties

Eucommia ulmoides (E. ulmoides) is a significant national strategic resource in China. It is a natural high quality rubber resource, with great development potential. We found large differences in rooting ability during adventitious root (AR) formation in two E. ulmoides improved varieties. Therefore, we used two improved varieties of E. ulmoides, ‘Huazhong 6’ (H6, with rooting rate 85.3%) and ‘Huazhong 8’ (H8, with rooting rate 22.5%) to explore the cutting rooting mechanism. In this study, we mainly determined the morphological development process of E. ulmoides cutting rooting, and compared the rooting-related indexes of the two improved varieties, and the changes in physiological indexes closely related to rooting, which include endogenous hormones, oxidases and nutrients in the phloem of the basal stem. The results showed that indole–3–acetic acid (IAA), zeatin riboside (ZR), IAA/ZR and indoleacetic acid oxidase (IAAO) were the key factors that caused big differences in rooting ability between the two E. ulmoides improved varieties. The increase in endogenous hormone IAA content and IAA/ZR value were necessary for the formation of AR. The increase in IAA content was beneficial to AR formation. The activity of IAAO was significantly negatively correlated with the rooting ability of the E. ulmoides cuttings. The high IAAO activity of the H8 cuttings led to the consumption of IAA. Although the content of IAA increased, the rooting conditions were not reached. The accumulation of nutrients before rooting also has an important effect on rooting; it is easy for cuttings to root when the carbon–nitrogen ratio (C/N) value is high. This research provides an improved understanding of the cellular and physiological underpinnings of the AR process in woody plants. In addition, it provides a theoretical basis and foundation for subsequent research on E. ulmoides cuttage technology.

Effect of light on growth and chlorophyll development in kiwifruit ex vitro and in vitro

Light is one of the most important environmental factors that strongly mediates plant physiological and morphological development. Few studies have investigated the effect of light on perennial fruit crops, which have long generation times and are large in size, that complicates the evaluation of plant responses to light in controlled environments. This study assessed the impact of light intensity on chlorophyll (Chl) variation in 41 kiwifruit cultivars during the growing season, and examined the physiological, morphological and gene expression changes of kiwifruit plantlets in vitro under different light qualities treatments, such as white light, red light (RL), blue light (BL) and a mixture of RL and BL with different ratios. The Chl content in 24.4% of kiwifruit varieties increased continuously with increasing sunlight intensity from April to August; but 34.15% of varieties remained unchanged and 41.5% of varieties decreased in July and August when kiwifruit plants were exposed to maximum solar radiation density and duration. The controlling experiment of light qualities showed that blue light was effective for the induction and accumulation of kiwifruit Chl contents and carbon nitrogen ratio (C/N ratio), as well as the numbers of guard cell plastids, whereas red light induced plant vegetative growth and increased starch and sucrose content in leaves. Furthermore, blue light induced higher expression of key genes for Chl biosynthesis than red light. These results indicate that kiwifruit plants exhibit strong morphological plasticity induced by light, and the development of kiwifruit can be induced by culturing the plants in vitro under a combination of BL and RL.

Composting of Olive Mill Pomace, Agro-Industrial Sewage Sludge and Other Residues: Process Monitoring and Agronomic Use of the Resulting Composts.

The viability of co-composting of olive mill pomace added to sewage sludge with other organic residues was evaluated and the agronomic use of the final composts was investigated. Two composting piles at different carbon-nitrogen ratios were performed, in which olive mill pomace (OMP), sewage sludge from vegetable processing (SS), fresh residues from artichoke processing residues (AR), and wheat straw (WS) were used. The two composting piles were placed inside a specially built greenhouse and a turning machine pulled by a tractor was used for turning and shredding the organic matrix (every 6 days) during the process. The humidity and temperature of organic matrices have been monitored and controlled during the entire composting process, which lasted 90 days. The process was also monitored to evaluate the microbiological safety of the final compost. The humidity of both piles was always kept just above 50% until the end of the thermophilic phase and the maximum temperature was about 50 °C during the thermophilic phase. The carbon-nitrogen ratio decreased from 21.4 and 28.2, respectively (initial value at day 1 in Pile A and B), to values ranging from 12.9 to 15.1, both composts that originated from the two different piles were microbiologically safe. During a two-year period, the effects of different types of compost on the main qualitative parameters of processing tomato and durum wheat was evaluated. Five fertilization treatments were evaluated for tomato and durum wheat crops: unfertilized control (TR1); compost A (TR2); compost B (TR3); ½ mineral and ½ compost A (TR4); and mineral fertilizer commonly used for the two crops (TR5). Concerning the processing tomato yield, TR5 and TR4 showed the best results (2.73 and 2.51 kg, respectively). The same trend was observed considering the marketable yield per plant. The only difference was related to the treatments that included the compost (2.32, 1.77, and 1.73 kg/plant for TR4, TR3, and TR2, respectively). As regards the qualitative parameters of tomato, the highest average weight of the fruits was found in the TR5, TR4, and TR3 treatments (respectively, 73.67 g, 70.34 g, and 68.10 g). For durum wheat, only the protein component was differentiated between treatments. Furthermore, wheat grain yield parameters generally increased by combined application of mineral fertilizer and compost.

Influence of Precipitation Change on Soil Respiration in Desert Grassland

Global climate change has significantly changed precipitation patterns. Soil respiration (SR), as an important pathway through which CO2 is released from the soil carbon pool into the atmosphere, may affect the carbon cycle process of terrestrial ecosystems and have a feedback effect on global climate change in response to precipitation change. However, at present there is limited understanding of how SR is affected by precipitation change. Field precipitation control experiments were conducted (with -40%, -20%, natural, 20%, and 40% precipitation) on desert grassland in the west of the Loess Plateau, to investigate the influence of precipitation change on SR dynamics and its relationship with soil water content, soil temperature, aboveground biomass, soil organic carbon, microbial biomass carbon, carbon-nitrogen ratio, and other factors. The results show that the diurnal variations of SR under different precipitation treatments were consistent in unimodal and bimodal models over three years. SR showed an increasing trend with added precipitation, relative to the control, and significant differences were observed between the second year (wetter) and the third year (drier) of the precipitation-manipulation experiment, indicating that precipitation changes had a legacy effect on SR. At the same time, SR was lowest under the -40% treatment and highest under the 40% treatment during the wetter year. The negative response of SR to precipitation exclusion treatments was stronger than the positive response to precipitation addition treatments. SR in drier years was significantly higher under precipitation addition treatments than the control, and the positive response of SR to increased precipitation treatment was significantly stronger than that under decreased precipitation treatment. In addition, soil water content, aboveground biomass, soil organic carbon, and carbon-nitrogen ratio were the environmental factors that obviously affected SR and increased with additional precipitation. SR increased with increases in soil water content, aboveground biomass, soil organic carbon, and carbon-nitrogen ratio, but decreased with increases in microbial biomass carbon. Among these factors, soil water content had the highest interpretation rate for SR, indicating that soil water content was the main environmental factor controlling SR in desert grassland. In both wetter and drier years, the amplitude of plant biomass input was lower than the amplitude of SR output under precipitation change, indicating that precipitation change may be unfavorable to soil carbon sequestration, especially in drier years, when precipitation change has a stronger influence on carbon pool output. Therefore, precipitation changes on SR in desert grassland in various dry and wet years may have different influences on the carbon cycle process of ecosystems, thus providing a reference for regional carbon budget assessment.

Photocatalytic Advanced Oxidation Processes for Neutralizing Free Cyanide in Gold Processing Effluents in Arequipa, Southern Peru

Cyanide (CN−) from gold processing effluents must be removed to protect human health and the environment. Reducing the use of chemical reagents is desirable for small centralized and decentralized facilities. In this work, we aimed to optimize the use of ultraviolet (UV) radiation coupled with hydrogen peroxide (H2O2) to enhance the rate and extent of CN− removal in synthetic and actual gold processing effluents, from one centralized and one decentralized facility in southern Peru. Bench-scale studies conducted using H2O2 and ambient UV showed no significant effects on CN− destruction; however, experiments with higher UV intensity and H2O2 accelerated free CN− degradation. When a 1:1 stoichiometric ratio of CN−:H2O2 was tested, the highly concentrated effluent (1 g CN−/L) had a slower pseudo first-order rate constant (k = 0.0066 min−1) and took ~5 h longer to reach 99% destruction, compared with the low concentration effluent (100 mg CN−/L; k = 0.0306 min−1). Lastly, a TiO2 photocatalyst with low stoichiometric CN−:H2O2 ratios (1:0.1 and 1:0.2), in a compound parabolic solar concentrator, was tested to investigate the degradation of a high concentration effluent (1.28 g CN−/L). These results show a significant improvement to degradation rate within a 20 min period, advancing treatment options for mineral processing facilities.

Comparison of pulp sludge compost effectivity of three different decomposers to the growth of geronggang (Cratoxylon arborescens) seedlings

Pulp residue from liquid waste processing is suitable for compost materials, except for its high CN ratio so it needs composting to reduce the CN ratio. Geronggang is a native peat swamp species suitable for peat rehabilitation. The study aims to test pulp sludge compost quality enriched with three different decomposers to the growth of geronggang ( Cratoxylum arborescens ) seedlings. The sludge composting was incubated for a month using three species of decomposers, i.e., Phanerochaete chrysosporium (C); Penicillium citrinum and Penicillium oxalicum (CO); P. chrysosporium, P. citrinum and P. oxalicum (CCO). The compost is weighed and placed around the seedling's roots area with varies dosages equal to 2, 4, 6, 8, 10, 12, 14, and 16 ton ha -1 . The height and diameter of the seedlings were recorded for six months. Data was examined using ANOVA followed with DMRT at a 5% significance. The sludge compost in this study has CN ratio, Total N (%), P 2 O 5 (%) and K 2 O (%) about 40.22-44.5; 1.04-1.11; 1.05-1.13; 1.05-1.13, respectively. Statistically, the height increment of seedlings after the sludge compost application enriched with the CO was different from the CCO. However, the seedling's height rise was not statistically different at the dosages variation treatment. The raise of seedlings diameter after CO treatment at a dosage equal to 6 and 12 ton ha -1 was significantly different to the CCO at a dosage equal to 12 ton ha -1 . However, the rise of seedling's diameter was not significantly different at decomposers' variation treatment. The future study can be aimed to gain compost that meets the national standard.

The Distribution and Migration of 137Cs in Oak (Quercus serrata) and Cedar (Cryptomeria japonica) Forest Organic Fractions

To analyse the 137Cs distribution and migration under various fractions of organic matter layers, this study investigated easily recognizable, originally shaped organic L-fractions, and not easily recognizable, early fermented and fragmented organic F-fractions, of both oak (Quercus serrata) and cedar (Cryptomeria japonica) sampled from Osawa watershed sites at Nihonmatsu City, Fukushima Prefecture, Japan. The organic materials were put on top of soil columns from Field Museum (FM) Tamakyuryo in Hachioji City, Tokyo. The 137Cs vertical distribution in forest soil profiles was analyzed using the relaxation mass depth, ho (kg m−2). Soil columns with both L and F- organic layer fractions of both oak and cedar, labelled as Oak-L, Oak-F, Cedar-L and Cedar-F with four replications (n = 16), were set up by the laboratory column-based method and kept under five months’ incubation period. Soil columns after incubation were sampled at depths of 0–1 cm, 1–2 cm, 2–5 cm and 5–10 cm. Results of 137Cs inventory in the organic fractions showed that 86% (oak and cedar) of the total organic layer fractions 137Cs inventory accumulated within the F-layer, indicating that the transformation of litter is a huge source for potentially mobile 137Cs, especially the oak F-layer (67% 137Cs inventory) and further continuous transfer into the forest soil mineral layers. A higher ho in L treated soils (Oak-L and Cedar-L) compared to the F treatments implied that the low 137Cs amounts penetrated faster and deeper due to their water-soluble nature. Furthermore, Cedar-F showed a higher ho of 24.3 kg m−2 than Oak-F of ho, 14.0 kg m−2, and a significant positive relationship between 137Cs retention and total carbon (TC) (p < 0.05) suggested the influence of soil organic matter on 137Cs penetration and retention. The C/N (carbon nitrogen ratio) results revealed that organic matter fractions of high C/N including 137Cs, as observed in Cedar-F, in which decomposition does not advance, penetrates soil depths while the organic matter fraction of low C/N, observed in Oak-F, showed that decomposition advanced to release 137Cs which was held by adsorption unto the RIP (radiocesium interception potential) of soil surface. In addition, infiltration by water as a transportation process was suggested to largely influence the downward migration and retention of 137Cs at lower depths of Cedar-F.

Experimental study on shortcut simultaneous nitrogen removal in treating domestic sewage

To treat domestic sewage with high efficacy and low cost, the technology of shortcut simultaneous nitrogen removal was used with a new biofilm reactor. The influences on nitrogen removal effect by start-up procedure, nitrogen transformation characteristics and main factors (hydraulic retention time, dissolved oxygen, carbon-nitrogen ratio) were analyzed. The results indicate that: The reactor finished start-up of shortcut simultaneous nitrogen removal in 14 days of cultivation time after the biofilm cultured in the carrier. The ammonia nitrogen removal rate, simultaneous nitrification-denitrification rate and cumulative nitrite nitrogen rate respectively reached 91.3%, 82.7% and 63.4% in the last phase of start-up procedure. To remove ammonia nitrogen with the technology of shortcut simultaneous nitrogen removal efficiently and steadily, hydraulic retention time, dissolved oxygen, carbon-nitrogen ratio should be controlled in 3.56 hours, 1.5 mg/L and 5~8.

English

The chemical properties in the rhizosphere of fruit tree species were investigated during different season at CCS HAU, Hisar. Results revels that pH value, OC, N, P, K, Zn contents increased significantly with all the fruit orchards over control (uncultivated land). However, maximum pH, EC, OC, CN ratio, available N, P, K, Zn and Fe (8.30, 0.33 dS/m, 0.54 %, 11.63, 126.26 kg/ha, 32.24 kg/ha, 284.93 kg/ha, 2.10 ppm and 3.34 ppm) was found in aonla, sweet orange, jamun, jamun, guava, sweet orange, guava, ber and sweet orange, respectively. Highest EC, CEC, OC and available K were found in winter season but pH, EC, available N, Zn, Mn and B contents were recorded maximum in summer season.CN ratio and available P were maximum in rainy season. Inter row spaces soil had highest pH, CEC, CN ratio and Zn contents while maximum OC, Available N, P, K, Fe, Mn and B contents was observed under the canopy of fruit trees.

Efficient Lignin Decomposing Microbial Consortium to Hasten Rice-Straw Composting with Moderate GHGs Fluxes

We hypothesized that lignin decomposition microbial consortium would make rice-straw decomposition faster as straw contain around 15–24% lignin. In this study, we isolated aerobic lignin degrading microbes from four natural sources and based on their ability towards lignin degradation four microbial strains and their combination (2 bacteria (LB 8, LB 18) and 2 fungi (LF 3, LF 9) were selected for rice straw decomposition. The greenhouse gases emission, enzymatic activities (β-glucosidase, cellulase, laccase), reduction in lignin content, weight loss and carbon nitrogen ratio (C:N) were quantified during the process of decomposition. The β-glucosidase, cellulase and laccase activities were higher in compost where LB 18 + LF 3 consortium was applied as compared to others. The lignin content was also decreased (8.9–9.5 to 6.6–7.9%) gradually from initial to 28th days of composting under LB 18 + LF 3. We found the microbial consortium LB 18 + LF 3 decomposed the rice straw relatively faster than other strains/consortium tested as indicated by lowering of C:N ratio and reduction of lignin, hemicellulose, and cellulose contents of 60, 19.2, 41.5 and 10.3%, respectively at 28th day of composting compared to initial values. However, higher, methane and carbon dioxide fluxes were also observed at 28th days of composting (1.36 and 200.7 mg m−2 h−1) with no significant trend in nitrous oxide fluxes. Further, the consortium identified could be tested for in-situ straw decomposition with proper moisture management to evaluate its potential in field condition. Therefore, we conclude that use of lignin decomposing microbial consortium has the potential to hasten the composting of rice straw in large scale.Graphic abstract

Production of Bio-Fertilizer through Composting of Tannery Wastes with Cow- Dung and Rice Bran

Tannery waste is made from nutrients and organic compounds that enhance soil fertility thereby improving plants and microbial growths. This study was designed to investigate the application of tannery wastes to form compost material in a mixture with cow-dung and rice brand. The treatments were prepared and tested for a period of sixty (60) days. The compost was characterized by electric conductivity (EC) of 10.11µs/cm, pH of 7.62 and Carbon-Nitrogen (C:N) ratio of 28.8. Total concentrations of Chromium, Lead, Cadmium, Copper, Zinc and Iron in mg/kg were 57.2, 0.92, 12.50, 60.50, 13.60 and 1101.00 respectively. However, total bacterial counts decreased from 8.2 x108cfu/g to 1.8 x106cfu/g after the 60days. The compost characteristics indicate about 80% germination index which may suggest the removal of most of the phototoxic compounds.

Response of exoelectrogens centered consortium to nitrate on collaborative metabolism, microbial community, and spatial structure

Exoelectrogens are widespread and participate in building up interspecies electron-sharing network between anaerobic microbes. However, the exoelectrogens-centered electron-sharing networks might be affected by over-released nitrate, which competes with solid minerals or electrodes as the electron acceptor. The knowledge on the mechanism on the response of exoelectrogens-centered community to nitrate disturbance is still limited. This study applied the microbial electrochemical system as a platform and provided insights into the response of electroactive biofilm to nitrate under a constant potential of + 0.2 V. Under a fixed carbon–nitrogen ratio of 6, the biofilm partially processed dissimilatory nitrate reduction to ammonium (DNRA) transitorily and gradually loses electron-output capability. After sufficient succession, the biofilm achieved complete denitrification without ammonia accumulation and started to acquire electrons from the electrode. With nitrate disturbance, the exoelectrogens-centered biofilm dominated by Geobacter sp. preferred to cooperate with highly enriched hydrogenotrophic denitrifiers for mutualistic growth with hydrogen as the electron mediator. Different scan rates of CVs also suggested the mediated electron transfer process. The extracellular polymer substrate (EPS) serving as a network contributed to aggregates formation. The enhanced humic acid and protein secretion in the EPS of nitrate-affected biofilm suggested frequent interactions between cells. Therefore, a mutualistic interaction was established between exoelectrogens and denitrifiers under nitrate stress.

Rhodotorula kratochvilovae CCY 20-2-26-The Source of Multifunctional Metabolites.

Multifunctional biomass is able to provide more than one valuable product, and thus, it is attractive in the field of microbial biotechnology due to its economic feasibility. Carotenogenic yeasts are effective microbial factories for the biosynthesis of a broad spectrum of biomolecules that can be used in the food and feed industry and the pharmaceutical industry, as well as a source of biofuels. In the study, we examined the effect of different nitrogen sources, carbon sources and CN ratios on the co-production of intracellular lipids, carotenoids, β–glucans and extracellular glycolipids. Yeast strain R. kratochvilovae CCY 20-2-26 was identified as the best co-producer of lipids (66.7 ± 1.5% of DCW), exoglycolipids (2.42 ± 0.08 g/L), β-glucan (11.33 ± 1.34% of DCW) and carotenoids (1.35 ± 0.11 mg/g), with a biomass content of 15.2 ± 0.8 g/L, by using the synthetic medium with potassium nitrate and mannose as a carbon source. It was shown that an increased C/N ratio positively affected the biomass yield and production of lipids and β-glucans.

Distribution characteristics and influencing factors of soil carbon and nitrogen under different vegetation types in Zibaishan National Nature Reserve

Objective The objective of this study is to explore the distribution characteristics of soil carbon and nitrogen under different vegetation types in Zibaishan National Nature Reserve, and analyze its main influencing factors. Method Soil samples were collected from different soil layers, including loam types (Q. aliena forest and P. armandii forest) and sandy types (Q. aliena var. acuteserrata forest, Q. variabilis forest, B. platyphylla forest). The content, density and storage of soil organic carbon (SOC), total nitrogen (TN), and carbon-nitrogen ratio (C∶N) under 5 different vegetation types were compared, and the relationship between SOC, TN, C∶N and soil physical and chemical properties was analyzed. Result (1)The content, density and storage of SOC and TN in the loam soil were significantly higher than those in the sandy soil (P＜0.05). As for loam soil, Q. aliena forest had the largest content, density and storage of SOC and TN, followed by P. armandii forest. For sandy soil, the order from large to small was B. platyphylla forest, Q. aliena var. acuteserrata forest, and Q. variabilis forest. (2)With the increase of soil depth, the content, density and storage of SOC and TN in 0−30 cm soil layer decreased significantly (P＜0.05). (3)Soil C∶N in different soil layers of different vegetation types showed little regularity or differences. The value of C∶N was 9.94−16.23, indicating strong mineralization ability of organic matter. (4)Soil water content (SWC) and bulk density (BD) were the main factors affecting soil SOC and TN content, while SWC and pH were the main factors affecting C∶N. Conclusion There are significant differences in content, density and storage of SOC and TN under different vegetation types, and SWC is a key factor affecting SOC, TN and C∶N. This study has a certain reference value for the protection and management of forest ecosystem in the reserve. [Ch, 4 fig. 5 tab. 36 ref.]

Carbon and Nitrogen Sourcing in High Elevation Landscapes of Mustang in Central Nepal

Mustang valley in the central Himalaya of Nepal is a unique landscape formed by massive soil mass during a glacial period, which is attributed to a mix of vegetations and long agricultural history. Soil nutrients and their sourcing is highly important to understand the vegetation assemblage and land productivity in this arid zone. Twenty soil samples (from 0 to 20 cm depth) were collected from three landscape positions in Mustang district: valley, ridge, and midslope. We explored nutrient sourcing using natural abundance carbon (δ13C) and nitrogen isotope (δ15N) employing isotope ratio mass spectrophotometry. The results showed that the total soil carbon (TC) and total nitrogen (TN) ranged from 0.3 to 10.5% and 0.3 to 0.7%, respectively. Similarly, the CN ratio ranged from 0.75 to 15.6, whereas soil pH ranged from 6.5 to 7.5. Valley soil showed higher values of TN, CN, and soil pH than the ridge and midslope soils. The valleys had more positive δ15N signatures than ridge and midslope, which indicates higher inorganic and organic N fertilizer inputs in the valley bottom than in the midslope and ridge. This suggests that a higher nutrient content in the valley bottom likely results from agro-inputs management and the transport of nutrients from the ridge and midslope. Soil pH and CN ratio were a non-limiting factor of nutrient availability in the study regions. These findings are crucial in understanding the nutrient dynamics and management in relation to vegetation and agricultural farming in this unique topography of the Trans-Himalayan zone of Mustang in central Nepal.

Effect of lactose standardization of milk using low-concentration factor ultrafiltration: Effect of reducing the lactose-to-casein ratio on the properties of milled-curd Cheddar cheese

The pH of cheese is determined by the amount of lactose fermented and the buffering capacity of the cheese. The buffering capacity of cheese is largely determined by the protein contents of milk and cheese and the amount of insoluble calcium phosphate in the curd, which is related to the rate of acidification. The objective of this study was to standardize both the lactose and casein contents of milk to better control final pH and prevent the development of excessive acidity in Cheddar cheese. This approach involved the use of low-concentration factor ultrafiltration of milk to increase the casein content (∼5%), followed by the addition of water, ultrafiltration permeate, or both to the retentate to adjust the lactose content. We evaluated milks with 4 different lactose-to-casein ratios (L:CN): 1.8 (control milk), 1.4, 1.1, and 0.9. All cheesemilks had similar total casein (2.3%) and fat (3.4%) contents. These milks were used to make milled-curd Cheddar cheese, and we evaluated cheese composition, texture, functionality, and sensory properties over 9 mo of ripening. Cheeses made from milks with varying levels of L:CN had similar moisture, protein, fat, and salt contents, due to slight modifications during manufacture (i.e., cutting the gel at a smaller size than control) as well as control of acid development at critical steps (i.e., cutting the gel, whey drainage, salting). As expected, decreasing the L:CN led to cheeses with lower lactic acid, residual lactose, and insoluble Ca contents, as well as a substantial pH increase during cheese ripening in cheeses. The L:CN ratio had no significant effect on the levels of primary and secondary proteolysis. Texture profile analysis showed no significant differences in hardness values during ripening. Maximum loss tangent, an index of cheese meltability, was lower until 45 d for the L:CN 1.4 and 0.9 treatments, but after 45 d, all reduced L:CN cheeses had higher maximum loss tangent values than the control cheese (L:CN 1.8). Sensory analyses showed that cheeses made from milks with reduced L:CN contents had lower acidity, sourness, sulfury notes, and chewdown cohesiveness. Standardization of milk to a specific L:CN ratio, while maintaining a constant casein level in the milk, would allow Cheddar cheese manufacturers to have tighter control of pH and acidity.

GAT1 Gene, the GATA Transcription Activator, Regulates the Production of Higher Alcohol during Wheat Beer Fermentation by Saccharomyces cerevisiae.

Uncoordinated carbon-nitrogen ratio in raw materials will lead to excessive contents of higher alcohols in alcoholic beverages. The effect of GAT1 gene, the GATA transcription activator, on higher alcohol biosynthesis was investigated to clarify the mechanism of Saccharomyces cerevisiae regulating higher alcohol metabolism under high concentrations of free amino nitrogen (FAN). The availability of FAN by strain SDT1K with a GAT1 double-copy deletion was 28.31% lower than that of parent strain S17, and the yield of higher alcohols was 33.91% lower. The transcript levels of the downstream target genes of GAT1 and higher alcohol production in the double-copy deletion mutant suggested that a part of the effect of GAT1 deletion on higher alcohol production was the downregulation of GAP1, ARO9, and ARO10. This study shows that GATA factors can effectively regulate the metabolism of higher alcohols in S. cerevisiae and provides valuable insights into higher alcohol biosynthesis, showing great significance for the wheat beer industry.