Production of cyclic adenosine monophosphate by Arthrobacter sp. A302 using fed-batch fermentation with pH-shift control

Characterization and optimization of abamectin-a powerful antiparasitic from a local Streptomyces avermitilis isolate

Abamectin (ABA) constitutes a big commodity for pharmaceutical companies because it generates about one billion dollar annual sale. Avermectins (AVMs) and their naturally occurring analogues, milbemycins (MILs), meilingmycins (MEIs), ivermectin (IVE), abamectin (ABA), and nemadectin (NEM), represent one of the most developed antiparasitic agents. Abamectin is a mixture of avermectin B1a and avermectin B1b. The production of abamectin by Streptomyces avermitilis is a complicated process and separation of two fractions is quite difficult; commercial product contains more than 80% of Bla and less than 20% of B1b components. The main goal of the study was the identification and optimization of fermentation conditions to raise the production of abamectin from Egyptian S. avermitilis. The qualitative and quantitative analysis of avermectins was carried out by thin layer chromatography (TLC) and 6538 Q-TOF with Agilent 1290 UHPLC. The process of identification was carried out by using production medium containing 30 g/L corn starch, and 0.725 g/L CaCO3, pH 7, 8% inoculum size and incubated at 32.5 °C. The enhancement of the production of abamectin is a big challenge with commercial and industrial importance, as its output is insufficient for human consumption.

Comparative transcriptomic and proteomic analysis of Arthrobacter sp. CGMCC 3584 responding to dissolved oxygen for cAMP production

Arthrobacter sp. CGMCC 3584 is able to produce high yields of extracellular cyclic adenosine monophosphate (cAMP), which plays a vital role in the field of treatment of disease and animal food, during aerobic fermentation. However, the molecular basis of cAMP production in Arthrobacter species is rarely explored. Here, for the first time, we report the comparative transcriptomic and proteomic study of Arthrobacter cells to elucidate the higher productivity of cAMP under high oxygen supply. We finally obtained 14.1% and 19.3% of the Arthrobacter genome genes which were up-regulated and down-regulated notably, respectively, with high oxygen supply, and identified 54 differently expressed proteins. Our results revealed that high oxygen supply had two major effects on metabolism: inhibition of glycolysis, pyruvate metabolism, nitrogen metabolism, and amino acid metabolism (histidine, branched-chain amino acids and glutamate metabolism); enhancement of the tricarboxylic acid cycle and purine metabolism. We also found that regulation of adenylate cyclase and phosphodiesterase was not significant under high oxygen supply, suggesting efficient cAMP export might be important in cAMP production. These findings may contribute to further understanding of capacities of Arthrobacter species and would be highly useful in genetic regulation for desirable production.