Moisture content and aeration control mineral nutrient solubility in poultry litter.

Poultry litter waste is typically land-applied as a soil amendment but repeated application in the vicinity of poultry houses has led to phosphorus accumulation in soil. Such application can also lead to runoff that causes eutrophication. Most farmers store litter under dry conditions or compost the litter prior to land application, but it is not clear if these approaches are best from a nutrient management-perspective. The objective of this study was to investigate the effects of moisture content and active aeration on soluble mineral forms of nitrogen and phosphorus in poultry litter incubated for roughly one month. Mineral forms of nutrients are immediately plant-available upon field application and also most conducive to low-cost stripping and recovery methods. Litters were incubated at 50% and 70% moisture content with and without active aeration. Litter aeration led to significant ammonia losses and a consequent decline in litter pH but it had no effect on phosphate solubility. Moisture content during litter incubation governed the levels of plant-available phosphate and nitrification. High (70%) moisture led to 41%-78% higher plant-available phosphate (4.2-4.8 mg/g litter) compared to litters with 50% moisture content (2.7-3.0 mg/g litter). In contrast, the 50% moisture litters experienced 5-6 fold higher levels of nitrification (0.11-0.12 mg NO3-N/g litter) than litters with 70% moisture content (0.02 mg NO3-N/g litter), regardless of aeration. The implication is that lower-moisture litter storage is likely best for field application because phosphate is less soluble under neutral-alkaline conditions and therefore less likely to end up in runoff. In contrast, higher-moisture litter storage may be amenable to low-cost processes to leach and recover phosphate from litter.

Azospirillum brasilense reduces oxidative stress in the green microalgae Chlorella sorokiniana under different stressors.

In this study, we investigated oxidative stress in the green microalgae, Chlorella sorokiniana, in co-culture with the plant growth promoting bacteria (PGPB), Azospirillum brasilense. This relationship was studied in the absence of an exogenous stressor, under copper stress, and under nitrogen limitation stress. We confirmed that copper and nitrogen limitation induced algal oxidative stress and reductions in chlorophyll content. In all cases, the presence of A. brasilense lowered the accumulation of intracellular reactive oxygen species (ROS) while promoting chlorophyll content. This effect was driven, in part, by A. brasilense's secretion of the auxin hormone, indole-3-acetic acid, which is known to mitigate stress in higher plants. The findings of the present study show that stress mitigation by A. brasilense resulted in suppressed starch accumulation under nitrogen limitation stress and neutral lipid accumulation under copper stress. In fact, A. brasilense could almost completely mitigate oxidative stress in C. sorokiniana resulting from nitrogen limitation, with ROS accumulation rates comparable to the axenic control cultures. The biotechnological implication of these findings is that co-culture strategies with A. brasilense (and similar PGPB) are most effective for high growth applications. A second growth stage may be needed to induce accumulation of desired products.

Algal photosynthetic aeration increases the capacity of bacteria to degrade organics in wastewater.

Wastewater treatment is an energy-intensive process and a net emitter of greenhouse gas emissions. A large fraction of these emissions is due to intensive aeration of aerobic bacteria to facilitate break-down of organic compounds. Algae can generate dissolved oxygen at levels in excess of saturation, and therefore hold the potential to partially displace or complement mechanical aeration in wastewater treatment processes. The objective of this study was to develop an internally consistent experimental and modeling approach to test the hypothesis that algal photosynthetic aeration can speed the removal of organic constituents by bacteria. This framework was developed using a simplified wastewater treatment process consisting of a model bacteria (Escherichia coli), a model algae (Auxenochlorella protothecoides), and a single carbon source that was consumable by bacteria only. This system was then tested both with and without the presence of algae. A MATLAB model that considered mass transfer and biological kinetics was used to estimate the production and consumption of O2 and CO2 by algae and bacteria. The results indicated that the presence of algae led to 18-66% faster removal of COD by bacteria, and that roughly one-third of biochemical oxygen demand was offset by algal photosynthetic aeration.

Anaerobic microbial communities can influence algal growth and nutrient removal from anaerobic digestate.

The objective of this work was to test the impact of anaerobic digester microorganisms on algal growth, composition, and nutrient removal from digestate. Culture studies were carried out to determine the impacts of the microbial community on treatment of poultry litter anaerobic digestate by two strains of green algae: Auxenochlorella protothecoides and Chlorella sorokiniana. The results showed that the community doubled the growth of A. protothecoides but had no impact on C. sorokiniana growth. A similar result was observed for nutrient removal where the microbial community increased the capacity of A. protothecoides to remove ammonium and phosphate. The impact of the microbial community on biomass composition was minimal for both algae types.

Aerobic bacterial pretreatment to overcome algal growth inhibition on high-strength anaerobic digestates.

Coupling anaerobic digestion and algae cultivation has attracted attention as a sustainable means of treating high-strength wastewaters. In such a scenario, nutrients from the liquid anaerobic digestate are used by algae to produce biomass. However, use of full-strength digestate results in poor algal growth and nutrient removal. Most researchers have overcome this challenge by diluting digestate 10-30 fold prior to algae growth but such dilution rates demand large amounts of fresh water, posing challenges for scale-up. The objectives of this study were to 1) assess whether ammonium, turbidity, and heavy metals in digestate were the primary sources of inhibition for a highly-nutrient tolerant strain of Chlorella sorokiniana, and, 2) develop a biological pretreatment strategy to overcome algal growth inhibition on full strength digestate. Ammonia toxicity, turbidity, and heavy metals have been commonly hypothesized as the source of algal growth inhibition, but our results showed that these factors were not critical inhibitors of C. sorokiniana. Dose response studies showed that C. sorokiniana could grow robustly on 3,500 mg/L ammonium. Regardless, full strength digestates of wastewater sludge and food waste were very inhibitory to C. sorokiniana. We utilized a pretreatment approach using activated sludge which led to robust algal growth on full-strength digestate. High growth rates of 250-500 mg/L/d were achievable on pretreated digestates despite very high ammonium levels of ∼2,000 mg/L. Pretreating digestate also led to significantly faster algal nutrient uptake compared to untreated digestate (p < 0.001).

Cultivation of Green Microalgae in Bubble Column Photobioreactors and an Assay for Neutral Lipids.

There is significant interest in the study of microalgae for engineering applications such as the production of biofuels, high value products, and for the treatment of wastes. As most new research efforts begin at laboratory scale, there is a need for cost-effective methods for culturing microalgae in a reproducible manner. Here, we communicate an effective approach to culture microalgae in laboratory-scale photobioreactors, and to measure the growth and neutral lipid content of that algae. Instructions are also included on how to set up the photobioreactor system. Although the example organisms are species of Chlorella and Auxenochlorella, this system can be adapted to cultivate a wide range of microalgae, including co-cultures of algae with non-algae species. Stock cultures are first grown in bottles to produce inoculum for the photobioreactor system. Algae inoculum is concentrated and transferred to photobioreactors for cultivation in batch mode. Samples are collected daily for the optical density readings. At the end of the batch culture, cells are harvested by centrifuge, washed, and freeze dried to obtain a final dry weight concentration. The final dry weight concentration is used to create a correlation between the optical density and the dry weight concentration. A modified Folch method is subsequently used to extract total lipids from the freeze-dried biomass and the extract is assayed for its neutral lipid content using a microplate assay. This assay has been published previously but protocol steps were included here to highlight critical steps in the procedure where errors frequently occur. The bioreactor system described here fills a niche between simple flask cultivation and fully-controlled commercial bioreactors. Even with only 3-4 biological replicates per treatment, our approach to culturing algae leads to tight standard deviations in the growth and lipid assays.

Leaching and anaerobic digestion of poultry litter for biogas production and nutrient transformation.

Anaerobic digestion of poultry litter is a potentially sustainable means of stabilizing this waste while generating biogas. However, technical challenges remain including seasonality of litter production, low C/N ratios, limited digestibility of bedding, and questions about transformation of nutrients during digestion. This study investigated biogas production and nutrient transformations during anaerobic digestion of poultry litter leachate and whole litter. Use of fresh litter collected from within the house was also compared to waste litter cake that was stored outdoors on the farm. The results showed that litter leachates had higher biomethane potential (0.24-0.30 L/gVS) than whole litter (0.15-0.16 L/gVS) and the insoluble bedding material left after leaching (0.08-0.13 L/gVS). Leachates prepared from waste litter cake had lower uric acid and higher acetic acid concentrations than fresh litter indicating that decomposition had occurred during storage. Consequently, waste litter cake had faster initial biogas production but lower final biogas yields compared to fresh litter. In all reactors, uric and acetic acids were completely consumed during digestion, phosphate levels decreased but ammonium levels increased. The results demonstrate that poultry litter leachate is amenable to digestion despite a low C/N ratio and that the remaining insoluble bedding material has been partially stripped of its nutrients. Moreover, litter can be stored prior to digestion but some losses in biomethane potential should be expected due to decomposition of organics during storage.

Cost Effectiveness of Operative Versus Non-Operative Treatment of Geriatric Type-II Odontoid Fracture.

STUDY DESIGN: Cost-effectiveness analysis. OBJECTIVE: To examine the cost-effectiveness of operative versus non-operative treatment of type-II odontoid fractures in patients older than 64 years old. SUMMARY OF BACKGROUND DATA: Significant controversy exists regarding the optimum treatment of geriatric patients with type-II odontoid fractures. Operative treatment leads to lower rates of non-union but carries surgical risks. Non-operative treatment does not carry surgical risks but has higher non-union rates. METHODS: A decision-analytic model was created to compare operative and non-operative treatment of type-II odontoid fractures among three age cohorts (65-74, 75-84, >84) based on expected costs, quality-adjusted life years (QALYs) and incremental cost-effectiveness ratios (ICERs; cost per QALY gained). Age-specific mortality rates for both treatments, costs for treatment, and complication rates were taken from the literature, and data from 2010 US life tables were used for age-specific life expectancy. Costs of complications were estimated using data obtained at a level-I trauma center using micro-costing. Sensitivity analyses of all model parameters were conducted. RESULTS: Among the 65- to 74-year-old cohort, operative treatment was more costly ($53,407 vs. $30,553) and more effective (12.00 vs. 10.11 QALY), with an ICER of $12,078/QALY. Among the 75- to 84-year-old cohort, operative treatment was more costly ($51,308 vs. $29,789) and more effective (6.85 vs. 6.31 QALY), with an ICER of $40,467/QALY. Among the over-84 cohort, operative treatment was dominated by non-operative treatment as it was both more costly ($45,978 vs. $28,872) and less effective (2.48 vs. 3.73 QALY). The model was robust to sensitivity analysis across reasonable ranges for utility of union, disutility of complications and delayed surgery, and probabilities of non-union and complications. CONCLUSION: Operative treatment is cost-effective in patients age 65 to 84 when using $100,000/QALY as a benchmark but less effective and more costly than non-operative treatment in patients older than 84 years. LEVEL OF EVIDENCE: 2.

Co-culturing Chlorella minutissima with Escherichia coli can increase neutral lipid production and improve biodiesel quality.

Lipid productivity and fatty acid composition are important metrics for the production of high quality biodiesel from algae. Our previous results showed that co-culturing the green alga Chlorella minutissima with Escherichia coli under high-substrate mixotrophic conditions enhanced both culture growth and crude lipid content. To investigate further, we analyzed neutral lipid content and fatty acid content and composition of axenic cultures and co-cultures produced under autotrophic and mixotrophic conditions. We found that co-culturing C. minutissima with E. coli under high substrate conditions (10 g/L) increased neutral lipid content 1.9- to 3.1-fold and fatty acid content 1.5- to 2.6-fold compared to equivalent axenic C. minutissima cultures. These same co-cultures also exhibited a significant fatty acid shift away from trienoic and toward monoenoic fatty acids thereby improving the quality of the synthesized fatty acids for biodiesel production. Further investigation suggested that E. coli facilitates substrate uptake by the algae and that the resulting growth enhancement induces a nitrogen-limited condition. Enhanced carbon uptake coupled with nitrogen limitation is the likely cause of the observed neutral lipid accumulation and fatty acid profile changes.

Anterior vs. posterior approach for total hip arthroplasty, a systematic review and meta-analysis.

The objective of this study is to compare the clinical, radiographic and surgical outcomes among patients undergoing primary THA performed via the anterior versus posterior approach. We searched numerous sources and eventually included 17 studies, totaling 2302 participants. In terms of post-operative pain and function, the anterior approach was significantly favored in 4 studies at short-term follow-up. Pooled estimates showed a significant difference in favor of the anterior approach in terms of length of stay and dislocations. Current evidence comparing outcomes following anterior versus posterior THA does not demonstrate clear superiority of either approach. Until more rigorous, randomized evidence is available, we recommend choice of surgical approach for THA be based on patient characteristics, surgeon experience and surgeon and patient preference.

Microplate assay for quantitation of neutral lipids in extracts from microalgae.

Lipid quantitation is widespread in the algae literature, but popular methods such as gravimetry, gas chromatography and mass spectrometry (GC-MS), and Nile red cell staining suffer drawbacks, including poor quantitation of neutral lipids, expensive equipment, and variable results among algae species, respectively. A high-throughput microplate assay was developed that uses Nile red dye to quantify neutral lipids that have been extracted from algae cells. Because the algal extracts contained pigments that quenched Nile red fluorescence, a mild bleach solution was used to destroy pigments, resulting in a nearly linear response for lipid quantities in the range of 0.75 to 40 µg. Corn oil was used as a standard for quantitation, although other vegetable oils displayed a similar response. The assay was tested on lipids extracted from three species of Chlorella and resulted in close agreement with triacylglycerol (TAG) levels determined by thin layer chromatography. The assay was found to more accurately measure algal lipids conducive to biodiesel production and nutrition applications than the widely used gravimetric assay. Assay response was also consistent among different species, in contrast to Nile red cell staining procedures.

Effects of Escherichia coli on mixotrophic growth of Chlorella minutissima and production of biofuel precursors.

Chlorella minutissima was co-cultured with Escherichia coli in airlift reactors under mixotrophic conditions (glucose, glycerol, and acetate substrates) to determine possible effects of bacterial contamination on algal biofuel production. It was hypothesized that E. coli would compete with C. minutissima for nutrients, displacing algal biomass. However, C. minutissima grew more rapidly and to higher densities in the presence of E. coli, suggesting a symbiotic relationship between the organisms. At an initial 1% substrate concentration, the co-culture produced 200-587% more algal biomass than the axenic C. minutissima cultures. Co-cultures grown on 1% substrate consumed 23-737% more of the available carbon substrate than the sum of substrate consumed by E. coli and C. minutissima alone. At 1% substrate, total lipid and starch productivity were elevated in co-cultures compared to axenic cultures indicating that bacterial contamination was not detrimental to the production of biofuel precursors in this specific case. Bio-fouling of the reactors observed in co-cultures and acid formation in all mixotrophic cultures, however, could present challenges for scale-up.

Proximal biceps tendon tear in an adolescent tennis player.

The diagnosis of a torn biceps tendon in athletes who use overhead throwing or swinging motions can be difficult to make because there is no one physical examination finding that will confirm the diagnosis, and because magnetic resonance imaging, although sometimes helpful, does not image the length of the biceps tendon adequately. We report a case of an isolated partial biceps tendon tear in an adolescent female athlete who was diagnosed during arthroscopy after the tendon was pulled into the joint. The tendon was cut and a tenodesis was performed. Two years after the surgical procedure, the patient was without pain and returned to playing tennis at her previous level.

Fly Fishing-related lesser tuberosity avulsion in an adolescent.

Stress lesions of the shoulder in athletic and active adolescents are most commonly associated with overhead sports. One of the most uncommon stress lesions of the shoulder in adolescents is an avulsion of the lesser tuberosity of the proximal humerus. To our knowledge, only 2 other cases of lesser tuberosity avulsions from repetitive motion have been reported, both of which were secondary to baseball pitching.This article describes a case of an isolated partial avulsion of the lesser tuberosity of the humerus in an adolescent as a result of repetitive stress from fly fishing. The patient had no symptoms in his shoulder until after casting for approximately 10 hours a day for 3 days. He presented with anterior shoulder pain that worsened with abduction and external rotation. On examination, he had tenderness over the lesser tuberosity and pain with subscapularis muscle testing, such as the lift-off test. He had a negative apprehension sign but no signs of a superior labrum tear. Conventional radiography with an axillary view confirmed the diagnosis. He recovered with rest and gradual return to activities. Two years after injury, the patient had no limitations functionally, and his shoulder examination was normal.This case highlights the importance of being aware that (1) this lesion can occur in activities other than baseball, (2) characteristic physical findings exist with this lesion, (3) obtaining an axillary radiograph can confirm diagnosis, and (4) these avulsions can be treated successfully with nonoperative interventions.

Subscapularis strain from swinging a baseball bat in an adolescent with closed physis.

A healthy 16-year-old female baseball player was referred by her pediatrician for evaluation of pain in her right, dominant shoulder. The pain had begun insidiously 4 weeks previously after several sessions of batting practice and had worsened until she could not participate in baseball, even with low doses of ibuprofen. She was not participating in any other sports or weight lifting and had had no previous incidents of shoulder pain, but she did have a history of being able to voluntarily subluxate the right shoulder since she was a child. Her voluntary shoulder subluxation and reduction did not reproduce or worsen her pain. Results from her physical examination and radiographs were normal. Magnetic resonance imaging showed edema in the subscapularis muscle consistent with acute muscle strain. She was treated with 6 weeks of rest, ice, and anti-inflammatory medication as needed. She returned to baseball and hitting during the following 6 weeks with no limitations.