A transdisciplinary approach to the initial validation of a single cell protein as an alternative protein source for use in aquafeeds.

The human population is growing and, globally, we must meet the challenge of increased protein needs required to feed this population. Single cell proteins (SCP), when coupled to aquaculture production, offer a means to ensure future protein needs can be met without direct competition with food for people. To demonstrate a given type of SCP has potential as a protein source for use in aquaculture feed, a number of steps need to be validated including demonstrating that the SCP is accepted by the species in question, leads to equivalent survival and growth, does not result in illness or other maladies, is palatable to the consumer, is cost effective to produce and can easily be incorporated into diets using existing technology. Here we examine white shrimp (Litopenaeus vannamei) growth and consumer taste preference, smallmouth grunt (Haemulon chrysargyreum) growth, survival, health and gut microbiota, and Atlantic salmon (Salmo salar) digestibility when fed diets that substitute the bacterium Methylobacterium extorquens at a level of 30% (grunts), 100% (shrimp), or 55% (salmon) of the fishmeal in a compound feed. In each of these tests, animals performed equivalently when fed diets containing M. extorquens as when fed a standard aquaculture diet. This transdisciplinary approach is a first validation of this bacterium as a potential SCP protein substitute in aquafeeds. Given the ease to produce this SCP through an aerobic fermentation process, the broad applicability for use in aquaculture indicates the promise of M. extorquens in leading toward greater food security in the future.

Appropriate use of screening and diagnostic tests to foster high-value, cost-conscious care.

Unsustainable rising health care costs in the United States have made reducing costs while maintaining high-quality health care a national priority. The overuse of some screening and diagnostic tests is an important component of unnecessary health care costs. More judicious use of such tests will improve quality and reflect responsible awareness of costs. Efforts to control expenditures should focus not only on benefits, harms, and costs but on the value of diagnostic tests-meaning an assessment of whether a test provides health benefits that are worth its costs or harms. To begin to identify ways that practicing clinicians can contribute to the delivery of high-value, cost-conscious health care, the American College of Physicians convened a workgroup of physicians to identify, using a consensus-based process, common clinical situations in which screening and diagnostic tests are used in ways that do not reflect high-value care. The intent of this exercise is to promote thoughtful discussions about these tests and other health care interventions to promote high-value, cost-conscious care.

High ethanol titers from cellulose by using metabolically engineered thermophilic, anaerobic microbes.

This work describes novel genetic tools for use in Clostridium thermocellum that allow creation of unmarked mutations while using a replicating plasmid. The strategy employed counter-selections developed from the native C. thermocellum hpt gene and the Thermoanaerobacterium saccharolyticum tdk gene and was used to delete the genes for both lactate dehydrogenase (Ldh) and phosphotransacetylase (Pta). The Δldh Δpta mutant was evolved for 2,000 h, resulting in a stable strain with 40:1 ethanol selectivity and a 4.2-fold increase in ethanol yield over the wild-type strain. Ethanol production from cellulose was investigated with an engineered coculture of organic acid-deficient engineered strains of both C. thermocellum and T. saccharolyticum. Fermentation of 92 g/liter Avicel by this coculture resulted in 38 g/liter ethanol, with acetic and lactic acids below detection limits, in 146 h. These results demonstrate that ethanol production by thermophilic, cellulolytic microbes is amenable to substantial improvement by metabolic engineering.

Complete genome sequence of the cellulolytic thermophile Clostridium thermocellum DSM1313.

Clostridium thermocellum DSM1313 is a thermophilic, anaerobic bacterium with some of the highest rates of cellulose hydrolysis reported. The complete genome sequence reveals a suite of carbohydrate-active enzymes and demonstrates a level of diversity at the species level distinguishing it from the type strain ATCC 27405.

Constraints on anaerobic respiration in the hyperthermophilic Archaea Pyrobaculum islandicum and Pyrobaculum aerophilum.

Pyrobaculum islandicum uses iron, thiosulfate, and elemental sulfur for anaerobic respiration, while Pyrobaculum aerophilum uses iron and nitrate; however, the constraints on these processes and their physiological mechanisms for iron and sulfur reduction are not well understood. Growth rates on sulfur compounds are highest at pH 5 to 6 and highly reduced (<-420-mV) conditions, while growth rates on nitrate and iron are highest at pH 7 to 9 and more-oxidized (>-210-mV) conditions. Growth on iron expands the known pH range of growth for both organisms. P. islandicum differs from P. aerophilum in that it requires direct contact with insoluble iron oxide for growth, it did not produce any extracellular compounds when grown on insoluble iron, and it lacked 2,6-anthrahydroquinone disulfonate oxidase activity. Furthermore, iron reduction in P. islandicum appears to be completely independent of c-type cytochromes. Like that in P. aerophilum, NADH-dependent ferric reductase activity in P. islandicum increased significantly in iron-grown cultures relative to that in non-iron-grown cultures. Proteomic analyses showed that there were significant increases in the amounts of a putative membrane-bound thiosulfate reductase in P. islandicum cultures grown on thiosulfate relative to those in cultures grown on iron and elemental sulfur. This is the first evidence of this enzyme being used in either a hyperthermophile or an archaeon. Pyrobaculum arsenaticum and Pyrobaculum calidifontis also grew on Fe(III) citrate and insoluble iron oxide, but only P. arsenaticum could grow on insoluble iron without direct contact.

Laboratory screening at preventive health exams: trend of testing, 1978-2004.

BACKGROUND: Routine laboratory screening at preventive health exams continues to be a common practice despite expert opinion dating back to 1979 that supports only a few screening tests for apparently healthy adults. This report describes trends in such testing over a 27-year period. METHODS: Primary care physicians were surveyed five times between 1978 and 2004 at a yearly educational meeting in Colorado. Based on case vignettes describing two apparently healthy adults, physicians indicated which laboratory tests they would routinely order. RESULTS: Of a total of 2364 surveys collected during years 1978, 1983, 1988, 1999, and 2004, the corresponding percentage of physicians respondents who state they would order the following tests for a healthy man aged 35 years were: complete blood count (CBC) (87, 75, 73, 49, 46); urinalysis (UA) (93, 86, 79, 52, 44); chemistry panel (CHEM) (57, 48, 36, 43, 55); and electrocardiogram (ECG) (37, 27, 24, 9, 6). For a healthy woman aged 55 years, the corresponding percentages for each test were: CBC (89, 89, 86, 64, 67); UA (96, 93, 88, 62, 55); CHEM (70, 70, 66, 57, 76); ECG (63, 51, 51, 33, 29); and thyroid stimulating hormone (14, 20, 28, 42, 57). CONCLUSIONS: Although currently practicing physicians continue to report that they order screening tests for apparently healthy people, this practice appears to have decreased over the past 27 years. This trend may reflect expert guidelines and emphasis on medical cost containment.

Effect of a mailed brochure on appointment-keeping for screening colonoscopy: a randomized trial.

BACKGROUND: Even when primary care physicians have face-to-face discussions with patients before referring them for screening colonoscopy, patient nonadherence can be substantial. Often, primary care physicians lack sufficient time to educate patients and address their potential misconceptions and fears about this procedure. OBJECTIVE: To test whether an informational brochure sent to patients' home addresses after referral for screening colonoscopy would increase patient completion of the procedure. DESIGN: Randomized, controlled trial. SETTING: 2 general internal medicine practices affiliated with the University of Colorado Health Sciences Center. PATIENTS: 781 consecutive patients 50 years of age or older referred by their primary care physicians for screening colonoscopy. INTERVENTION: Patients were randomly assigned to receive usual care (control group) versus usual care plus an informational brochure (intervention group). The brochure was mailed within 10 days of referral for screening colonoscopy; it mentioned the name of the patient's primary care physician and encouraged patients to schedule a procedure. It also described colorectal cancer and polyps and the similar lifetime risks for colorectal cancer for men and women, colonoscopy and risk for perforation, the nature of bowel preparation for the procedure, and alternative screening tests. MEASUREMENTS: Rates of adherence to screening colonoscopy in the 2 study groups. RESULTS: The overall adherence rate was 11.7 percentage points (95% CI, 5.1 to 18.4 percentage points) greater in the intervention group than in the control group (70.7% vs. 59.0%). Older patients were more adherent than younger patients. Patients with low-income insurance plans, such as Medicaid, were less adherent despite being sent a brochure. LIMITATIONS: The small number of clinical practices and minority patients may limit generalizability. In addition, it was not possible to determine the degree to which adherence was influenced by a reminder to schedule a procedure versus detailed information about colonoscopy. CONCLUSIONS: An inexpensive mailed brochure is an effective way to increase patient adherence to primary care physician referral for screening colonoscopy.

Characterization of dissimilatory Fe(III) versus NO3- reduction in the hyperthermophilic archaeon Pyrobaculum aerophilum.

The hyperthermophilic archaeon Pyrobaculum aerophilum used 20 mM Fe(III) citrate, 100 mM poorly crystalline Fe(III) oxide, and 10 mM KNO3 as terminal electron acceptors. The two forms of iron were reduced at different rates but with equal growth yields. The insoluble iron was reduced when segregated spatially by dialysis tubing, indicating that direct contact with the iron was not necessary for growth. When partitioned, there was no detectable Fe(III) or Fe(II) outside of the tubing after growth, suggesting that an electron shuttle, not a chelator, may be used as an extracellular mediator of iron reduction. The addition of 25 and 50% (vol vol(-1)) cell-free spent insoluble iron media to fresh media led to growth without a lag phase. Liquid chromatography analysis of spent media showed that cultures grown in iron, especially insoluble iron, produced soluble extracellular compounds that were absent or less abundant in spent nitrate medium. NADH-dependent ferric reductase activity increased approximately 100-fold, while nitrate reductase activity decreased 10-fold in whole-cell extracts from iron-grown cells relative to those from nitrate-grown cells, suggesting that dissimilatory iron reduction was regulated. A novel 2,6-anthrahydroquinone disulfonate oxidase activity was more than 580-fold higher in iron-grown cells than in nitrate-grown cells. The activity was primarily (>95%) associated with the membrane cellular fraction, but its physiological function is unknown. Nitrate-grown cultures produced two membrane-bound, c-type cytochromes that are predicted to be monoheme and part of nitrite reductase and a bc1 complex using genome analyses. Only one cytochrome was present in cells grown on Fe(III) citrate whose relative abundance was unchanged.