Amino acid uptake profiling of wild type and recombinant Streptomyces lividans TK24 batch fermentations

Streptomyces lividans is considered an interesting host for the secretory production of heterologous proteins. To obtain a good secretion yield of heterologous proteins, the availability of suitable nitrogen sources in the medium is required. Often, undefined mixtures of amino acids are used to improve protein yields. However, the understanding of amino acid utilization as well as their contribution to the heterologous protein synthesis is poor.In this paper, amino acid utilization by wild type and recombinant S. lividans TK24 growing on a minimal medium supplemented with casamino acids is profiled by intensive analysis of the exometabolome (metabolic footprint) as a function of time. Dynamics of biomass, substrates, by-products and heterologous protein are characterized, analyzed and compared. As an exemplary protein mouse Tumor Necrosis Factor Alpha (mTNF-α) is considered.Results unveil preferential glutamate and aspartate assimilation, together with glucose and ammonium, but the associated high biomass growth rate is unfavorable for protein production. Excretion of organic acids as well as alanine is observed. Pyruvate and alanine overflow point at an imbalance between carbon and nitrogen catabolism and biosynthetic fluxes. Lactate secretion is probably related to clump formation. Heterologous protein production induces a slowdown in growth, denser clump formation and a shift in metabolism, as reflected in the altered substrate requirements and overflow pattern. Besides glutamate and aspartate, most amino acids are catabolized, however, their exact contribution in heterologous protein production could not be seized from macroscopic quantities.The metabolic footprints presented in this paper provide a first insight into the impact and relevance of amino acids on biomass growth and protein production. Type and availability of substrates together with biomass growth rate and morphology affect the protein secretion efficiency and should be optimally controlled, e.g., by appropriate medium formulation and substrate dosing. Overflow metabolism as well as high biomass growth rates must be avoided because they reduce protein yields. Further investigation of the intracellular metabolic fluxes should be conducted to fully unravel and identify ways to relieve the metabolic burden of plasmid maintenance and heterologous protein production and to prevent overflow.     

Scaling Up Paediatric HIV Care with an Integrated,Family-Centred Approach: An Observational Case Study from Uganda

Family-centred HIV care models have emerged as an approach to better target children and their caregivers for HIV testing and care, and further provide integrated health services for the family unit’s range of care needs. While there is significant international interest in family-centred approaches, there is a dearth of research on operational experiences in implementation and scale-up. Our retrospective case study examined best practices and enabling factors during scale-up of family-centred care in ten health facilities and ten community clinics supported by a non-governmental organization, Mildmay, in Central Uganda. Methods included key informant interviews with programme management and families, and a desk review of hospital management information systems (HMIS) uptake data. In the 84 months following the scale-up of the family-centred approach in HIV care, Mildmay experienced a 50-fold increase of family units registered in HIV care, a 40-fold increase of children enrolled in HIV care, and nearly universal coverage of paediatric cotrimoxazole prophylaxis. The Mildmay experience emphasizes the importance of streamlining care to maximize paediatric capture. This includes integrated service provision, incentivizing care-seeking as a family, creating child-friendly service environments, and minimizing missed paediatric testing opportunities by institutionalizing early infant diagnosis and provider-initiated testing and counselling. Task-shifting towards nurse-led clinics with community outreach support enabled rapid scale-up, as did an active management structure that allowed for real-time review and corrective action. The Mildmay experience suggests that family-centred approaches are operationally feasible, produce strong coverage outcomes, and can be well-managed during rapid scale-up.     

Assessment of sorghum genetic resources of Ethiopia for anthracnose (Colletotrichum sublineolum Henn.) resistance and agronomic traits

Sorghum anthracnose caused by Colletotrichum sublineolum Henn. is one of the key diseases limiting sorghum production and productivity. Development of anthracnose‐resistant sorghum genotypes possessing yield‐promoting agronomic traits is an important breeding goal in sorghum improvement programs. The objective of this study was to determine the responses of diverse sorghum genetic resources for anthracnose resistance and agronomic traits to identify desirable lines for breeding. A total of 366 sorghum collections and three standard checks were field evaluated during the 2016 and 2017 cropping seasons. Lines were artificially inoculated with a virulent pure isolate of the pathogen. Anthracnose disease severity was assessed to calculate the area under disease progress curve (AUDPC). Agronomic traits such as panicle length (PL), panicle width (PW), head weight (HW) and thousand grain weight (TGW) were measured. Lines showed highly significant differences (p < .001) for anthracnose severity, AUDPC and agronomic traits. Among the collections 32 lines developed levels of disease severity between 15% and 30% in both seasons. The following sorghum landraces were selected: 71708, 210903, 74222, 73955, 74685, 74670, 74656, 74183, 234112, 69412, 226057, 214852, 71420, 71484, 200126, 71557, 75120, 71547, 220014, 228179, 16212, 16173, 16133, 69088, 238388, 16168 and 71570. These landraces had a relatively low anthracnose severity possessing farmer‐preferred agronomic traits. The selected genotypes are useful genetic resources to develop anthracnose‐resistant sorghum cultivars.     

Rates of anti-tuberculosis drug resistance in Kampala-Uganda are low and not associated with HIV infection

Background

Drug resistance among tuberculosis patients in sub-Saharan Africa is increasing, possibly due to association with HIV infection. We studied drug resistance and HIV infection in a representative sample of 533 smear-positive tuberculosis patients diagnosed in Kampala, Uganda.

Methods/Principal Findings

Among 473 new patients, multidrug resistance was found in 5 (1.1%, 95% CI 0.3–2.5) and resistance to any drug in 57 (12.1%, 9.3–15.3). Among 60 previously treated patients this was 7 (11.7%, 4.8–22.6) and 17 (28.3%; 17.5–41.4), respectively. Of 517 patients with HIV results, 165 (31.9%, 27.9–36.1) tested positive. Neither multidrug (adjusted odds ratio (OR^adj) 0.7; 95% CI 0.19–2.6) nor any resistance (OR^adj 0.7; 0.43–1.3) was associated with HIV status. Primary resistance to any drug was more common among patients who had worked in health care (OR^adj 3.5; 1.0–12.0).

Conclusion/Significance

Anti-tuberculosis drug resistance rates in Kampala are low and not associated with HIV infection, but may be associated with exposure during health care.