Penicillin-binding proteins of protoplast and sporoplast membranes of Streptomyces griseus strains

Membrane-bound penicillin-binding proteins (PBPs) of two Streptomyces griseus strains that sporulate well in liquid and solid medium have been investigated during the course of their life-cycle. The PBP patterns were analyzed by sodium dodecylsulphate polyacrylamide-gel electrophoresis and fluorography. One strain (No. 45 H) has only a single band (mol wt: 27,000) in early log phase, and two additional PBPs of higher mol wt (69,000 and 80,000) in the late log phase. The other strain (No. 2682) possessed two bands with mol wts 27,000 and 38,000 which did not change during its vegetative phase. In strain No. 2682, a new PBP with a mol wt of 58,000 appeared in spore membranes while one of those (mol wt 38,000) present in mycelial membranes disappeared. Our results suggest that appearance of the new PBP in the spore may be associated with the sporulation process. The major PBP band (mol wt: 27,000) present in all stages of the life cycle of these strains, may be characteristic of S. griseus while the other PBPs reflect certain stages of the life cycle. A new method was developed for the production of spore protoplasts by consecutive enzymatic treatments.

Street-connectedness and education in Kenya: Experiences of formal schooling as rationale for inclusive pedagogies of practice

This paper contributes to the literature on street-connectedness and inclusive education, presenting original research findings from two Kenyan studies aiming to understand street-connected young people’s experiences of education. The first focused on transitioning from the street into education or training to explore the challenges of making that transition. The second, on young people who had lived on the street for extended periods of time and were still there at the time of data generation. From these studies, significant understandings emerged concerning: a) education as motivating initial migrations to the street; b) the role of fear, embarrassment and shame in preventing young people going (back) into formal education; and c) how acceptance and support are key to overcoming feelings of not belonging and challenges faced when transitioning from the street into schools. The paper provides empirical evidence that should be considered when planning inclusive education provision for street-connected young people globally

The penicillin receptor in Streptomyces

Kinetics and optical studies of Streptomyces DD-carboxypeptidases-transpeptidases led to the conclusion that the donor, acceptor, and penicillin sites on these enzymes are different but not independent and that penicillin acts as a modifier of the conformation of the protein. In the presence of penicillin, the penicillin-sensitive enzymes would be frozen in a conformation that prevents catalytic activity

Rapport II.11. Une conséquence des épandages de lisier de porcs sur les sols bretons : l'enrichissement en nitrates et en calcium des solutions du sol

Animal productions (pigs, poultry, cattle) have strongly increased for a few years in Brittany. Animal manures are land-spread and henceforth play an important role on the fertilisation of the ground. When badly managed, these spreadings set up pollution, especially by accumulation nitrates in the waters. The extraction, by porous ceramic cups, of the waters of soil receiving pig slurry spreadings, seems to be an interesting way for appreciating the respective part played by the morphological features of the soil, and by the amounts of spreading, on the chemical composition of those waters and consequently on the risks of pollution of the landscapes. Those waters are more often rich in calcium and nitrates. The exportations of mineral elements by leaching take place, to a great extent, within a short period, in December and January.Les productions animales (porcins, volailles, bovins) se sont fortement développées en Bretagne depuis 1960. Les déjections animales sont épandues sur les sols et jouent désormais un rôle important sur la fertilisation des terres. Lorsqu'ils sont mal conduits, ces épandages créent une pollution, notamment par accumulation de nitrates dans les eaux. L'extraction, par un système de bougies poreuses en céramique, des eaux de sols soumis à des épandages de lisier de porc, se révèle un moyen intéressant d'apprécier le rôle des caractéristiques morphologiques du sol, des doses d'épandage, sur la composition chimique de ces eaux et sur les risques de pollution des paysages. Ces eaux sont le plus souvent de faciès nitraté-calcique. Les exportations d'éléments minéraux par lixiviation prennent place, pour une bonne part, dans un délai de temps très court, en Décembre-Janvier.Cheverry Claude, Bouille S., Bedier J. Rapport II.11. Une conséquence des épandages de lisier de porcs sur les sols bretons : l'enrichissement en nitrates et en calcium des solutions du sol. In: L'assainissement de demain. L'hydraulique des eaux pluviales et usées. Compte-rendu des XVIIes journées de l'hydraulique. Nantes,14-16 septembre 1982. Tome 1, 1982

Streptomyces K15 DD-peptidase-catalysed reactions with ester and amide carbonyl donors.

In water, the purified 26 000-Mr membrane-bound DD-peptidase of Streptomyces K15 hydrolyses the ester carbonyl donor Ac2-L-Lys-D-Ala-D-lactate (release of D-lactate) and the amide carbonyl donor Ac2-L-Lys-D-Ala-D-Ala (release of D-alanine) with accumulation of acyl- (Ac2-L-Lys-D-alanyl-)enzyme. Whereas hydrolysis of the ester substrate proceeds to completion, hydrolysis of the amide substrate is negligible because of the capacity of the K15 DD-peptidase for utilizing the released D-alanine in a transfer reaction (Ac2-L-Lys-D-Ala-D-Ala + D-Ala----Ac2-L-Lys-D-Ala-D-Ala + D-Ala) that maintains the concentration of the amide substrate at a constant level. In the presence of an amino acceptor X-NH2 (Gly-Gly or Gly-L-Ala) related to the Streptomyces peptidoglycan, both amide and ester carbonyl donors are processed without detectable accumulation of acyl-enzyme. Under proper conditions, the acceptor activity of water and, in the case of the amide substrate, the acceptor activity of the released D-alanine can be totally overcome so that the two substrates are quantitatively converted into transpeptidated product Ac2-L-Lys-D-Ala-NH-X (and hydrolysis is prevented). Experimental evidence suggests that the amino acceptor modifies both the binding of the carbonyl donor to the enzyme and the ensuing rate of enzyme acylation

Biofouling potential indicators to assess pretreatment and mitigate biofouling in SWRO membranes: A short review

Many desalination plants still struggle to control biological fouling in seawater reverse osmosis (SWRO) systems as there are no standard methods to monitor this type of fouling. Strategies to control biofouling in SWRO systems have been proposed such as antifouling coating and lowering biofouling potential in SWRO feedwater through pretreatment processes. Measuring biofouling potential in the pretreatment and SWRO feedwater has gained increased interest due to its direct link to biofouling. Moreover, this approach can be used as an early warning system allowing for taking corrective actions in the pretreatment processes to meet the required SWRO feedwater quality. This article presents the biofouling potential methods/tools developed for seawater, their applications to monitor and assess raw seawater, SWRO pretreatment and SWRO feedwater, and how these methods are employed to control SWRO biofouling membrane systems. The reported removal efficiency of biofouling potential during SWRO pretreatment processes was found to be low to moderate. Threshold values for biofouling limitation were then proposed based on several lab and plant studies. Research on biofouling potential has provided insight into SWRO pretreatment performance optimisation and biofouling control. Future research is anticipated to determine better pretreatment processes and to identify robust threshold values for mitigating biofouling in SWRO membranes