scholarly journals Streptomyces sp. 1S1 isolated from Southern coast of the Red Sea as a renewable natural resource of several bioactive compounds

Author(s):  
Azal A. Mothana ◽  
Hassan A. Al-Shamahy ◽  
Ramzi A. Mothana ◽  
Jamal M. Khaled ◽  
Adnan J. Al-Rehaily ◽  
...  
2015 ◽  
Vol 12 ◽  
pp. 296-301 ◽  
Author(s):  
Diaa T.A. Youssef ◽  
Jihan M. Badr ◽  
Lamiaa A. Shaala ◽  
Gamal A. Mohamed ◽  
Faida H. Bamanie
Keyword(s):  

Author(s):  
Ivica Kisić

Soil is a thin (up to 50cm) loose top layer of the Earth's surface, located between the lithosphere and atmosphere. Total available land area on Earth is limited, and the soil is extremely important, and in one generation it is a non-renewable natural resource. Unfortunately, nowadays the soil is, next to water, one of the most endangered natural resources. Among the many processes of soil damage, which is not being addressed at this point, is the growing importance placed on soil contamination. Contaminated soil is the soil in which human or natural activity has increased the content of harmful substances whose concentrations may be harmful to human activity, that is, for the production of plants or animals.


Mathematics ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 2053
Author(s):  
M’hamed Gaïgi ◽  
Idris Kharroubi ◽  
Thomas Lim

In this work, we study an optimization problem arising in the management of a natural resource over an infinite time horizon. The resource is assumed to evolve according to a logistic stochastic differential equation. The manager is allowed to harvest the resource and sell it at a stochastic market price modeled by a geometric Brownian process. We assume that there are delay constraints imposed on the decisions of the manager. More precisely, starting harvesting order and selling order are executed after a delay. By using the dynamic programming approach, we characterize the value function as the unique solution to an original partial differential equation. We complete our study with some numerical illustrations.


2019 ◽  
Vol 15 (4) ◽  
pp. 737-772 ◽  
Author(s):  
Alfonso Cruz ◽  
Tomas Reyes ◽  
Roberto Vassolo

ABSTRACTSize is an important antecedent of firm survival, and several studies theoretically sustain and empirically support a ‘liability of middleness’. Indeed, it is widely believed that companies should act strategically to either become large or remain small and occupy a niche position, because mid-sized firms face the strongest market selection pressures. This study challenges that logic in renewable natural resource industries. Measuring size as product-line scale and firm-level portfolio breadth, we argue that in industries characterized by cost competition, the lack of product differentiation, large capital investments, and sharp price oscillation, scale and breadth have a curvilinear effect on survival that favors mid-sized firms rather than penalizing them. An empirical analysis of the US pulp and paper (P&P) industry over the period 1970–2000 strongly supports our arguments. This study is particularly relevant for emerging economies, in which natural resource industries represent an important portion of the total economic activity.


2008 ◽  
Vol 10 (01) ◽  
pp. 73-100 ◽  
Author(s):  
FRANCISCO CABO ◽  
GUIOMAR MARTÍN-HERRÁN ◽  
MARÍA PILAR MARTÍNEZ-GARCÍA

This paper develops a trade model for a technologically leading country and a developing country that exploits a renewable natural resource. Technology diffuses from the technological leader to the developing country through foreign direct investment (FDI). Alternatively, innovative activities can also be carried out in the developing economy. We prove the existence and uniqueness of an equilibrium path along which both countries grow at the same rate, maintaining the natural-resource stock at a constant level. The saddle-point property for this equilibrium is proved and a sensitivity analysis is carried out. The steady-state growth rate and consumption under both scenarios are compared and the effect of resource abundance analyzed.


Author(s):  
Alka Rani ◽  
Khem Chand Saini ◽  
Felix Bast ◽  
Sunita Varjani ◽  
Sanjeet Mehariya ◽  
...  

Microorganisms including actinomycetes, archaea, bacteria, fungi, yeast, and micro algae are the auspicious source of vital bioactive compounds. In this review, the existing state of the art re-garding antimicrobial molecules from microorganisms has been summarized. The potential an-timicrobial compounds from actinomycetes, particularly Streptomyces sp.; archaea; fungi including endophytic and marine-derived fungi, mushroom; yeast, and microalgae were briefly described. Furthermore, this review briefly summarized the activity and mode of action of bacteriocins, a ribosomally synthesized antimicrobial peptides product of Eurotium sp., Streptomyces parvulus, S. thermophiles, Lactococcus lactis, etc. Bacteriocins have inherent properties such as targeting multi-ple-drug resistant pathogens, which allows them to be considered next-generation antibiotics. Similarly, Glarea lozoyensis derived antifungal lipohexpeptides i.e., pneumocandins, inhibits 1,3-β-glucan synthase of the fungal cell wall and acts as a precursor for the synthesis of caspo-fungin, is also elaborated. In conclusion, this review highlights the possibility of using microor-ganisms as an antimicrobial resource for biotechnological, nutraceutical, and pharmaceutical ap-plications. However, more investigations are still required to separate, purify, and characterize these bioactive compounds and transfer these primary drugs into clinically approved antibiotics.


Author(s):  
Loh Teng-Hern Tan ◽  
Learn-Han Lee ◽  
Bey-Hing Goh

A single Streptomyces strain often have the potential to produce more than one bioactive compound. Fermentation parameters include media compositions, temperature and pH, have great impact on the secondary metabolism of Streptomyces and subsequently on production of different microbial products. This review aims to consolidate the studies on the cultivation parameters used to enhance the production of secondary metabolite with anti-Vibrio activity from a single Streptomyces strain. In turn, this review sheds light on the possible alterations of the cultivation parameters to obtain desired anti-Vibrio compounds from Streptomyces sp. Furthermore, the bioactive compounds with anti-Vibrio activity identified from Streptomyces sp. were demonstrated to exhibit immense values for future antibacterial agent developments.


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