Continuous Culture System Research Articles

Interactive effects of CO2, temperature, and nitrate limitation on the growth and physiology of strain CCMP 1334 of the marine cyanobacterium Synechococcus (Cyanophyceae).

The marine cyanobacterium Synecococcus sp. (CCMP 1334) was grown in a continuous culture system on a 12:12 h light:dark cycle at all combinations of low and high pCO2 (400 and 1000 ppmv, respectively), nutrient availability (nitrate-limited and nutrient-replete conditions), and temperatures of 21, 24, 28, 32, and 35°C. The maximum nutrient-replete growth rate was ~1.15 day-1 at 32-35°C. Median nutrient-replete growth rates were higher at 1000 ppmv than at 400 ppmv pCO2 at all temperatures. Carbon:nitrogen ratios were independent of pCO2 at a fixed relative growth rate (i.e., growth rate ÷ nutrient-replete growth rate) but decreased with increasing temperature. Carbon:chlorophyll a ratios were decreased monotonically with increasing temperature and were higher under nitrate-limited than nutrient-replete conditions. Ratios of phycoerythrin to chlorophyll a were independent of growth conditions. Productivity indices were independent of temperature and nutrient limitation but were consistently higher at 1000 ppmv than 400 ppmv pCO2. Both growth rates and dark respiration rates were positively correlated with temperature, and the associated Q10 values were 2.2 and 2.3, respectively. A model of phytoplankton growth in which cellular carbon is allocated to structure, storage, or the light or dark reactions of photosynthesis accounted for the general patterns of cell composition and growth rate. This strain of Synechococcus appears well suited to changes in environmental conditions that are expected as the climate warms in response to anthropogenic emissions of CO2.

PSX-20 The inclusion of a tannin-based product evaluated in a typical feedlot diet under tropical conditions increases the molar proportion of propionate in a dual-flow continuous-culture system

Abstract The objective of the present study was to evaluate increasing levels of a tannin-based product and a monensin (positive control; unique dose) using a dual-flow continuous-culture system. Diets were randomly assigned to ten fermenters in a replicated 5 x 5 Latin square with three, 10-d experimental periods consisting of 7 d for adaptation and 3 d for sample collection. Four different levels were tested independently, resulting in 5 treatments: tannin at levels of 0 (negative control), 0.07, 0.14, and 0.21 (% of DM of the total diet) and monensin as positive control at 28 mg/kg DM. The tannin-based product was a specific blend of tannin and saponins, composed of quebracho and chestnut tannin extracts, SilvaFeed-BX). Diets were prepared as concentrate mixes that were combined with sugarcane bagasse, corn grain, dry distillers grain, citrus pulp, peanut meal, and urea. Liquid and solid flow rates were adjusted to 10 and 5.0%/h, respectively. Samples were collected for digestibility, ruminal fermentation, and microbial growth. The basal diet consisted of a typical finishing diet for beef cattle (16:84 roughage:concentrate ratio). All results were assessed for residual normality and variance homogeneity. All variables were fitted through generalized mixed models (GLIMMIX procedure) and compared by using Tukey test (multiple comparison) and polynomial regressions (tannin concentrations, which were analyzed for linear and quadratic responses. Partial data were presented in the table below. Total VFA concentration, molar proportion of butyrate, and total Branched-chain VFA were not affected by treatments (P > 0.05). Molar proportion of acetate of the tannin-based product at 0.07 % of DM tended to be decreased compared with all other treatments. Molar proportion of propionate increased quadratically (P = 0.05) reaching the peak at the level of 0.07 % of DM, which were greater than monensin treatment. In conclusion, our results indicate that a smaller dose of a tannin-based product (0.07 g/kg of DM) might manipulate ruminal fermentation by increasing molar proportion of propionate in typical feedlot diet fed under tropical conditions. This is important from an energetic standpoint for the animal host, since propionate is the precursor of glucose synthesis in ruminants.

90 Awardee Talk: Shedding light into the black box: The dual-flow continuous culture system and ruminal fermentation

Abstract Nutrients derived from ruminal fermentation supply a substantial amount of metabolizable nutrients for ruminants. These include amino acids, carbohydrates, fatty acids, vitamins, and fermentation end products, such as ammonia and volatile fatty acids. Furthermore, ruminal fermentation modifies dietary nutrients in such a way that nutrients reaching the small intestine for absorption may substantially differ from those being consumed in the diet. Therefore, understanding ruminal fermentation kinetics and quantification of nutrients flowing out of the rumen is an important aspect of ruminant nutrition. Accurate quantification of these nutrients, using in vivo experiments, is laborious, costly, and invasive, requiring surgical procedures such as ruminal, abomasal, and intestinal cannulas. To decrease the time and cost of experiments as well as the use of animals, in vitro methodologies are important tools in ruminant nutrition. Therefore, the objectives of this presentation are i) describe different in vitro methodologies, ii) discuss the advantages of in vitro methodologies, iii) discuss shortcomings of in vitro methodologies, and iv) describe potential developments that may improve in vitro methodologies. Having been used for decades, in vitro methodologies such as pure, batch, and continuous cultures have been well documented to investigate a wide array of aspects of nutrition, including the effects of different dietary compositions, individual fermentation end products, and impacts on the microbiome. However, both batch and pure cultures can result in a build-up of end products that may inhibit fermentation. Continuous culture, however, allows for the removal of end products but, similar to pure and batch cultures, is applicable only to ruminal fermentation and cannot provide information regarding intestinal digestion. The dual-flow continuous culture system (DFCC), developed in the 1970s and used by various laboratories in the USA and Europe consists of fermentation vessels of approximately 1.5 L that are capable of simulating ruminal fermentation for periods longer than 10 d. It has been extensively used and evaluated by meta-analyses. When compared with other in vitro methodologies, the DFCC has longer fermentation time, larger volume, and the possibility of sampling from the liquid and the solid flows. When compared with in vivo experiments the DFCC is faster, less costly, less invasive, allows for greater range of treatments, allows for more controlled condition, and isolates ruminal function. Limitations of the DFCC include it does not predict in vivo response, it assumes equal saliva flow and concentration, no effects of intake, no ruminal absorption, less retention of protozoa, possible differences in microbiome, and limited gas emission data. Therefore, while in vitro methodologies provide useful data into the field of ruminant nutrition, some in vitro methodologies are more robust than others. Furthermore, in vivo experiments are still the ideal approach for assessing nutrient utilization and necessary to evaluate animal responses.

In Vitro Resistance-Predicting Studies and In Vitro Resistance-Related Parameters-A Hit-to-Lead Perspective.

Despite the urgent need for new antibiotics, very few innovative antibiotics have recently entered clinics or clinical trials. To provide a constant supply of new drug candidates optimized in terms of their potential to select for resistance in natural settings, in vitro resistance-predicting studies need to be improved and scaled up. In this review, the following in vitro parameters are presented: frequency of spontaneous mutant selection (FSMS), mutant prevention concentration (MPC), dominant mutant prevention concentration (MPC-D), inferior-mutant prevention concentration (MPC-F), and minimal selective concentration (MSC). The utility of various adaptive laboratory evolution (ALE) approaches (serial transfer, continuous culture, and evolution in spatiotemporal microenvironments) for comparing hits in terms of the level and time required for multistep resistance to emerge is discussed. We also consider how the hit-to-lead stage can benefit from high-throughput ALE setups based on robotic workstations, do-it-yourself (DIY) continuous cultivation systems, microbial evolution and growth arena (MEGA) plates, soft agar gradient evolution (SAGE) plates, microfluidic chips, or microdroplet technology. Finally, approaches for evaluating the fitness of in vitro-generated resistant mutants are presented. This review aims to draw attention to newly emerged ideas on how to improve the in vitro forecasting of the potential of compounds to select for resistance in natural settings.

SF6 Tracer Technique to Estimate Methane Emission in a Dual-Flow Continuous Culture System: Test and Application

This study aimed to evaluate the sulfur hexafluoride (SF6) tracer technique for estimating methane (CH4) emissions in dual-flow continuous culture systems (DFCCS). In experiment 1 (Exp1), fermenters were filled with water, and known CH4 concentrations (0, 1.35, 2.93, or 4.43 g/d) were injected using permeation tubes with SF6 release rates (3.30 or 9.65 mg/d). Headspace gas was collected using canisters, and the SF6 technique estimated CH4 recovery. Experiment 2 (Exp2) involved a DFCCS fermentation trial with ruminal fluid from three Holstein cows, testing diets with soybean meal or its partial replacement (50%) by Chlorella or Spirulina. Headspace gas was collected at intervals post-feeding. Standard curves for SF6 and CH4 quantification were inadequate for DFCCS samples, with the CH4:SF6 ratio differing from standards, indicating the data needs further SF6 release rate evaluation. In Exp1, a high correlation (r = 0.97) was found between infused and calculated CH4, indicating good repeatability. Low and high SF6 rates performed similarly at low CH4 infusion, but high SF6 overestimated CH4 at high infusion. Exp2 showed CH4 emissions irrespective of SF6 rate and indicated reduced CH4 emissions and increased NDF degradation with algae-containing diets. Further evaluation of the SF6 tracer technique is warranted for DFCCS.

Estimating bacterial load in S. aureus and E. coli bacteremia using bacterial growth graph from the continuous monitoring blood culture system

BackgroundWe examined whether the time to positivity (TTP) and growth and detection plot graph (GDPG) created by the automated blood culture system can be used to determine the bacterial load in bacteremic patients and its potential association correlation with disease severity.MethodsKnown bacterial inocula were injected into the blood culture bottles. The GDPGs for the specific inocula were downloaded and plotted. A cohort of 30 consecutive clinical cultures positive for S. aureus and E. coli was identified. Bacterial load was determined by comparing the GDPG with the “standard” curves. Variables associated with disease severity were compared across 3 bacterial load categories (< 100, 100–1000, > 1000 CFU/mL).ResultsS. aureus growth was sensitive to the blood volume obtained whereas E. coli growth was less so. A 12-hour delay in sample transfer to the microbiology laboratory resulted in a decrease in TTP by 2–3 h. Mean TTP was 15 and 10 h for S. aureus and E. coli, respectively, which correlates with > 1000 CFU/mL and 500–1000 CFU/ml. For S. aureus, patients with a bacterial load > 100 CFU/mL had a higher mortality rate, (OR for death = 9.7, 95% CI 1.6–59, p = 0.01). Bacterial load > 1000 CFU/mL had an odds ratio of 6.4 (95% CI1.2-35, p = 0.03) to predict an endovascular source. For E. coli bacteremia, we did not find any correlations with disease severity.ConclusionGDPG retrieved from the automated blood culture system can be used to estimate bacterial load. S.aureus bacterial load, but not E.coli, was associated with clinical outcome.

Characteristics of soil physical and chemical properties on Arabica coffee land in Bener Meriah Regency

Bener Meriah Regency is one of the Arabica coffee producing areas in Aceh Province. This Arabica coffee has been cultivating for years by the Gayo people with a continuous cultivation system throughout the year. Continuous cultivation for years causes a decrease in soil fertility in both physical and chemical properties, resulting in a decrease in coffee production. This study aims to determine the physical and chemical characteristics of the soil on Arabica coffee land in Bener Meriah Regency. The study used a quantitative descriptive method through land surveys and analysis of data in the field and analysis of soil samples in the laboratory. Observations were made on 15 Land Units Type (LUT) obtained from the overlay of elevation maps, slope maps, soil type maps and existing coffee plantation maps of Bener Meriah Regency. Parameters observed included soil structure, soil permeability, soil aggregate stability, soil pH, total and available P. The results showed that the soil structure was classified as crumb, soil permeability was slow to fast, soil aggregate stability was classified as unstable to rather stable, soil pH was acid to rather acid, P total was very low to very high, and P available was very low.

Effects of Energy Feed Sources in Hanwoo Cattle Diets on Fermentation and Microbial Amino Acids Composition in a Rumen Simulation Continuous Culture System

Effects of Energy Feed Sources in Hanwoo Cattle Diets on Fermentation and Microbial Amino Acids Composition in a Rumen Simulation Continuous Culture System

Application of humic acid increases the economic value and yield of superior tobacco as well as improves the chemical and processing quality

AbstractThe overuse of nitrogen (N) fertilizer in the vegetable growing season leads to a high amount of soil residual N and a decrease of resistance to tobacco disease in the vegetable–tobacco continuous cultivation system, which will seriously threaten the sustainable development of tobacco production. Humic acid (HA) rich in bioactive substances and microelements may enhance leaf growth rate and improve the quality of tobacco. A two‐factor randomized block experiment was carried out over 2 years to evaluate the effects of additional applying HA (0 and 150 L ha−1) combined with three N rates (0, 60, and 90 kg N ha−1) on tobacco growth, economic value, chemical, and processing quality. Applying HA significantly increased the tobacco economic value by 5%–28%. The superior tobacco yields positively correlated with the economic value (R2 = 0.88), which was the key factor determining the increase of the economic value. The application of HA decreased the disease severity and increased the microelement uptake and the daily leaf growth rate in the prosperous growing stage which was positively correlated with the superior tobacco yield. Applying HA significantly improved the chemical quality and reduced the leaf midrib proportion. At the N rate of 60 kg N ha−1, HA showed the best effect of improving quality and increasing income. Our results demonstrated that the addition of HA can significantly improve the economic value and the chemical and processing quality of tobacco. The best effect can be achieved by adjusting the N rate appropriately according to the amount of soil residual N before transplanting tobacco seedlings.

Effects of monensin and cashew nut-shell extract on bacterial community composition in a dual-flow continuous culture system.

The objective of this study was to evaluate the effects of including monensin and two doses of CNSE in a high producing dairy cow diet on ruminal bacterial communities. A dual-flow continuous culture system was used in a replicated 4 × 4 Latin Square design. A basal diet was formulated to meet the requirements of a cow producing 45kg of milk per d (17% crude protein and 27% starch). There were four experimental treatments: the basal diet without any feed additive (CON), 2.5 μM monensin (MON), 100ppm CNSE granule (CNSE100), and 200ppm CNSE granule (CNSE200). Samples were collected from the fluid and solid effluents at 3, 6, and 9h after feeding; a composite of all time points was made for each fermenter within their respective fractions. Bacterial community composition was analyzed by sequencing the V4 region of the 16S rRNA gene using the Illumina MiSeq platform. Treatment responses for bacterial community structure were analyzed with the PERMANOVA test run with the R Vegan package. Treatment responses for correlations were analyzed with the CORR procedure of SAS. Orthogonal contrasts were used to test the effects of (1) ADD (CON vs. MON, CNSE100, and CNSE200); (2) MCN (MON vs. CNSE100 and CNSE200); and (3) DOSE (CNSE100 vs. CNSE200). Significance was declared at P ≤ 0.05. We observed that the relative abundance of Sharpea (P < 0.01), Mailhella (P = 0.05), Ruminococcus (P = 0.03), Eubacterium (P = 0.01), and Coprococcus (P < 0.01) from the liquid fraction and the relative abundance of Ruminococcus (P = 0.03) and Catonella (P = 0.02) from the solid fraction decreased, while the relative abundance of Syntrophococcus (P = 0.02) increased in response to MON when compared to CNSE treatments. Our results demonstrate that CNSE and monensin have similar effects on the major ruminal bacterial genera, while some differences were observed in some minor genera. Overall, the tested additives would affect the ruminal fermentation in a similar pattern.

Exclusive D-lactate-isomer production during a reactor-microbiome conversion of lactose-rich waste by controlling pH and temperature

Lactate is among the top-ten-biobased products. It occurs naturally as D- or L-isomer and as a racemic mixture (DL-lactate). Generally, lactate with a high optical purity is more valuable. In searching for suitable renewable feedstocks for lactate production, unutilized organic waste streams are increasingly coming into focus. Here, we investigated acid whey, which is a lactose-rich byproduct of yogurt production, that represents a considerable environmental footprint for the dairy industry. We investigated the steering of the lactate-isomer composition in a continuous and open culture system (HRT = 0.6 d) at different pH values (pH 5.0 vs. pH 6.5) and process temperatures (38°C to 50°C). The process startup was achieved by autoinoculation. At a pH of 5.0 and a temperature of 47°C-50°C, exclusive D-lactate production occurred because of the dominance of Lactobacillus spp. (> 95% of relative abundance). The highest volumetric D-lactate production rate of 722 ± 94.6 mmol C L−1 d−1 (0.90 ± 0.12 g L−1 h−1), yielding 0.93 ± 0.15 mmol C mmol C−1, was achieved at a pH of 5.0 and a temperature of 44°C (n = 18). At a pH of 6.5 and a temperature of 44°C, we found a mixture of DL-lactate (average D-to-L-lactate production rate ratio of 1.69 ± 0.90), which correlated with a high abundance of Streptococcus spp. and Enterococcus spp. However, exclusive L-lactate production could not be achieved. Our results show that for the continuous conversion of lactose-rich dairy waste streams, the pH was a critical process parameter to control the yield of lactate isomers by influencing the composition of the microbiota. In contrast, temperature adjustments allowed the improvement of bioprocess kinetics.

PSVI-30 Effects of Different Cobalt Sources on Ruminal Fermentation of Lactating Dairy Cow Diets in a Dual-Flow Continuous Culture System

Abstract The objective of this study was to evaluate the effects of different sources of cobalt in a lactating dairy cow diet on in vitro ruminal fermentation. All diets provided the same amount of supplemental Co (1 mg per kg of diet DM) included in a premix with a targeted inclusion level of 2.5% of diet DM. Treatments were cobalt carbonate (CON), and three alternative Co sources; alternative source 1 (AS1), alternative source 2 (AS2), and alternative source 3 (AS3). Eight dual-flow continuous culture fermenters were used in a replicated 4 × 4 Latin square. Experimental periods were 10 d (7 d adaptation and 3 d sample collection). Composite samples of daily effluents were collected and analyzed for NH3-N, lactate, and VFA concentration as well as for nutrient digestibility. Samples of ruminal content were collected from each fermenter at 0, 1, 2, 4, 6, and 8 h after feeding to determine lactate, NH3-N, and pH kinetics. All data were analyzed using PROC MIXED of SAS and the repeated variable of time was included for pH, lactate, and NH3-N. There were neither treatment effects nor interactions between treatment and time for pH, NH3-N, and lactate concentrations, indicating a similar Co kinetics across treatments. With regards to lactate pool, we did not observe treatment effects for L-lactate; however, we observed treatment effects for D-lactate and total-lactate as seen in Table 1. Analyses of total and individual VFA, N utilization, and nutrient degradation are still undergoing, hence, it is possible that Co sources have effects on ruminal fermentation.

The Optimization, Kinetics Model, and Lab-Scale Assessments of Phenol Biodegradation Using Batch and Continuous Culture Systems

Phenol was considered a severe hazard to all ecosystems even at low concentrations. The bioremediation process is an eco-friendly process for complete phenol degradation and bioelectricity generation. In the present study, a consortium of native isolates was used for phenol biodegradation and bioenergy generation using nano-graphite electrodes. The optimization of nutritional and environmental parameters using batch culture revealed that the optimum conditions for maximum phenol degradation and energy generation were inoculum concentration, 1%; incubation period, 48 h; phenol, 6 ppm; MgSO4, 70 mg/L; K2HPO4, 175 mg/L; and CaCl2, 1 mg/L. Phenol biodegradation reached 93.34% with a power density of 109.419 mW/cm3. A lab-scale bioreactor was used as a continuous culture with aeration rate, agitation speed, and dissolved oxygen of 0.5 v/v/m, 750 rpm, and 30%, respectively. On using the continuous culture, phenol biodegradation and bioenergy production reached 97.8% and 0.382 W/cm3, respectively. A kinetics study using Haldane’s kinetics model reported the best fit to achieve a significant correlation coefficient (R2) value (0.9865) reaching maximum specific growth rate with initial phenol concentration of approximately 9 mg L−1 where the specific growth rates (μ, h−1) varied with different initial phenol concentrations. In conclusion, the native isolated consortium could be considered as an economical and sustainable approach to phenol biodegradation in industrial wastewater as well as bioelectricity generation.

Effects of Microencapsulated Blend of Organic Acids and Pure Botanicals on the Ruminal Microbiota in an In Vitro Dual-Flow Continuous Culture System

The objective of the study was to evaluate the effects of dietary supplementation of a microencapsulated blend of organic acids and pure botanicals (mOAPBs) on the solid- and liquid-associated microenvironment (SAM and LAM, respectively) of the ruminal microbiome using an in vitro dual-flow continuous culture system. Ruminal content was incubated in eight fermenters and the basal diet was supplemented with increasing levels of mOAPBs (0; 0.12; 0.24; or 0.36% DM) which contained 55.6% hydrogenated and refined palm oil, 25% citric acid, 16.7% sorbic acid, 1.7% thymol, and 1% vanillin. All diets had a similar nutritional composition (16.1 CP, 30.9 NDF, and 32.0 starch, % DM basis). After 7 days of adaptation, a pooled sample across the days was collected in each period for identification of the microbiome of SAM and LAM. There was no effect of mOAPB on alpha-, beta-diversity, and microbial abundance. The SAM had a greater bacterial diversity and the principal component analysis demonstrated that it had a divergent bacterial profile from LAM. Additionally, SAM had an increased abundance of carbohydrate-degrading microorganisms. In summary, mOAPBs did not modulate the ruminal microbiome. The microenvironment microbiome of solid- and liquid-associated microenvironments were different, with SAM having a greater carbohydrate-degrading microorganism population.

Effect of mixtures of legume species on ruminal fermentation, methane, and microbial nitrogen production in batch and continuous culture (RUSITEC) systems

The effect of cicer milkvetch ( Astragalus cicer L.) and sainfoin ( Onobrychis viciifolia Scop.) on ruminal fermentation, methane production, and microbial nitrogen synthesis was assessed in two experiments. Experiment 1 analyzed two legumes, cicer milkvetch and sainfoin at two stages (vegetative and late flower) incubated with alfalfa ( Medicago sativa) at five inclusion rates 0:100; 25:75, 50:50, 75:25, and 100:0 (as DM) in batch culture. Experiment 2 analyzed vegetative cicer milkvetch and alfalfa incubated in ratios of 25:75, 50:50, 75:25, and 100:0 (as DM) in continuous culture systems (RUSITEC). In batch culture, increased dry matter disappearance (DMD), and propionate percentage (%total), and reduced methane (mg·g−1 DMD) occurred with vegetative cicer milkvetch inclusion. In RUSITEC, DMD linearly increased ( P &lt; 0.01), acetate:propionate ratio quadratically decreased, while ammonia (NH3-N) concentration ( P &lt; 0.01) and butyrate percentage (%total) linearly decreased ( P &lt; 0.05) with increasing inclusion of cicer milkvetch. No differences were observed for methane (CH4) production (mg·g−1 DMD), or short chain fatty acid (SCFA) production (mmol·day−1). Microbial nitrogen synthesis and efficiency of protein synthesis linearly increased ( P &lt; 0.05) with increased inclusion of cicer milkvetch. Results suggest cicer milkvetch may result in synchronicity of energy and nitrogen during rumen fermentation, which could enhance cattle production.

Dynamics of Ex Vivo Mesenchymal Stromal Cell Potency under Continuous Perfusion.

Mesenchymal stromal cells (MSCs) are a candidate for cell immunotherapy due to potent immunomodulatory activity found in their secretome. Though studies on their secreted substances have been reported, the time dynamics of MSC potency remain unclear. Herein, we report on the dynamics of MSC secretome potency in an ex vivo hollow fiber bioreactor using a continuous perfusion cell culture system that fractionated MSC-secreted factors over time. Time-resolved fractions of MSC-conditioned media were evaluated for potency by incubation with activated immune cells. Three studies were designed to characterize MSC potency under: (1) basal conditions, (2) in situ activation, and (3) pre-licensing. Results indicate that the MSC secretome is most potent in suppressing lymphocyte proliferation during the first 24 h and is further stabilized when MSCs are prelicensed with a cocktail of pro-inflammatory cytokines, IFNγ, TNFα, and IL-1β. The evaluation of temporal cell potency using this integrated bioreactor system can be useful in informing strategies to maximize MSC potency, minimize side effects, and allow greater control for the duration of ex vivo administration approaches.

Droop model identification via model-based design of experiments to describe microalgae nitrogen uptake in continuous photobioreactors

The comprehension of nutrients uptake and exploitation dynamics is a key aspect to increase the efficiency and the environmental sustainability of microalgal production at industrial scale. The Droop model is suitable for the description of the effect of nutrients on microalgal growth, but presents challenges in parameter identification due to the high correlation between parameters and the significant experimental effort required.Model-based design of experiments is employed to plan information-rich experiments for precise parameters estimation, based on dynamic variations of dilution rate and nitrogen concentration in a continuous photobioreactor growing microalga Tetradesmus obliquus. It is shown that only two optimal experiments of 8 days each are sufficient to attain a statistically satisfactory estimation of all model parameters, thus minimising time and resources. Validation experiments show that the model can capture nitrogen uptake dynamics effectively, and demonstrate that the design of optimal dynamic experiments allows calibrating the Droop model rapidly, making it a valuable tool for the study of nutrients dynamics in continuous microalgal cultivation systems.

Isolated Bacterial Resistance to Antibiotics and Common Pathogens that Cause Neonatal Sepsis

Objective: to record the frequency of isolating organisms causing early-onset neonatal sepsis resistant to common antibiotics, Methodology: This research was a cross-sectional study that was conducted in 2017 and 2018 at the Neonatal Intensive Care Unit of the Benazir Bhutto Hospital in Rawalpindi on 180 children who satisfied the following criteria and were delivered between 34 and 40 weeks of gestation either Spontaneous Vertex Delivery or Cesarean Section. The study was conducted on infants who were born between 34 and 40 weeks of gestation. Those newborns who had congenital defects, had had surgical intervention, had hypoxic ischemic encephalopathy, or had been treated with antibiotics were not included in the research. Every infant had three millilitres of its blood collected and stored in a sterile environment. The blood was placed into the Bactec 9240 blood culture bottles in a direct inoculation. After being transported to the BBH children's hospital pathology lab, the injection bottles were placed in a Bactee 9240 continuous monitoring blood culture system. The temperature inside the incubator was 37 degrees Celsius. The use of catalase, coagulase, and Dnase in the examination of Gram-positive bacteria was carried out. Using the Kirby-Bauer method, the isolated organism was put through a battery of tests to determine whether or not it was resistant to ampicillin, amikacin, tobramycin, cefotaxime, ceftazidime, ceftriaxone, meropenem, sulbactam, and vancomycin. Meuller Hinton Agar was the medium that was employed. Results: In our study, out of 140 cases, 65.71%(n=92) were between 1-48 hours and 34.29%(n=48) were between 49-72 hours, mean+sd was calculated as 35.96+16.65 hours, 47.86%(n=67) were male and 52.14%(n=73) were females. Frequency of isolated organisms shows that 27.86%(n=39) had S.Aureus, 22.14%(n=31) had E.Coli, 15%(n=21) had Staphylococcus epidermidis, 12.86%(n=18) had Klebseila and 22.14%(n=31) had others. Practical Implication: determination of the isolated bacterial resistance to antibiotics and common pathogens that cause neonatal sepsis would help in the appropriate and effective management of neonatal sepsis in our population Conclusion: Our results reveal that S.Aureus and E.Coli were the common showing 27.86% S.Aureus, 22.14% E.Coli, 15%, Staphylococcus epidermidis, 12.86% Klebseila and 22.14% had others isolates. organisms in EOS cases followed by Staphylococcus epidermidis and Klebseila whereas Ampicillin, Cefotaxime, Ceftriaxon, and Ceftazidime are also resistant in these cases. Keywords: Early onset neonatal sepsis, common pathogens, antimicrobial resistance of isolated organism

Location-specific cultivation techniques for Arabica coffee in Bener Meriah Regency

Gayo coffee is one of the leading commodities originating from the Gayo Highlands, one of which is Bener Meriah Regency. The Gayo coffee commodity cultivated by farmers is Arabica coffee, consisting of Gayo 1, Gayo 2, and Gayo 3 clones. Arabica coffee has been developed by the Gayo community for many years with a continuous cultivation system throughout the year. This coffee farming business is relatively advanced, various introductions have been made, which are based on experience gained from generation to generation (location specific) so that it can affect the performance of the coffee farming business being cultivated. The use of cultivated land for years with a coffee cultivation system causes a decrease in land fertility, resulting in a decrease in coffee production. This study aims to determine the location-specific cultivation techniques for Arabica coffee in Bener Meriah Regency that have been carried out by farmers from generation to generation. The method used is descriptive quantitative analysis using survey methods. The survey method was conducted by conducting direct interviews with respondents, namely farmers who cultivate Arabica coffee. Respondents were determined through Stratified Random Sampling. The results showed were generally farmers using mixed varieties in one garden (59.34%), the spacing varied generally 2.5 meters x 2.5 meters (59.34 %), 82.42% used organic and inorganic fertilizers, only 5.49% used organic fertilizers and 12.09% used inorganic fertilizers. Organic fertilizers are sourced from composted coffee husks. Soil and water conservation measures carried out in coffee plantations are only vegetative methods, the type of shade is generally Lamtoro (Leucaena leucocephala) plants. Generally, herbicides were used for weed control (83.52%) and only 12.09% famers used pesticides to control plant pest organisms.

Differential Diet and pH Effects on Ruminal Microbiota, Fermentation Pattern and Fatty Acid Hydrogenation in RUSITEC Continuous Cultures

The aim of this study was to distinguish effects due to diet composition from those triggered by ruminal pH on fermentation patterns and microbial profiles in a continuous culture system (RUSITEC). The study followed a 2 × 2 factorial design, with two diets varying in the proportions of forage and concentrate and two pH levels in the culture medium. RUSITEC fermenters were used to simulate rumen fermentation and feed digestibility, fermentation end-products, microbial protein synthesis, microbial community, and long-chain fatty acid profiles in the digesta were determined. Multivariate analyses were applied to summarize the overall results. High concentrate (34% cereal grain, 32% hay) diets were more digestible (p &lt; 0.05) than high forage (10% cereal grain, 78% hay) diets, resulting in a greater (p &lt; 0.05) formation of most fermentation end-products and microbial protein in the rumen. However, there were no significant (p &gt; 0.05) differences between diets in methane production. Ciliate protozoa, anaerobic fungi, some fibrolytic bacteria, hydrogenation of oleic acid, and relative proportion of conjugated linoleic acid were increased (p &lt; 0.05) with high forage diets. A decline in rumen pH from 6.8 to 6.4 decreased (p &lt; 0.05) feed digestibility, protein degradability, and the daily outputs of some fermentation end-products (gas, VFA, acetate, ammonia) but had no effect (p &gt; 0.05) on the synthesis of microbial protein, and on the output of methane, propionate, butyrate or lactate. Minor changes in microbial community profile or the fatty acid relative proportions were observed within this pH range. The overall multivariate analysis revealed a clear discrimination between high-concentrate and high-forage diets, with subtler and less-defined pH effects on ruminal fermentation and microbial communities.