First, the effect of different levels of nitrogen source on clavulanic acid (CA) production was evaluated in batch cultivations utilizing complex culture medium containing glycerol and three different levels of soy protein isolate (SPI). Cellular growth, evaluated in terms of the rheological parameter K, was highest with a SPI concentration of 30 g.L(-1) (4.42 g.L(-1) N total). However, the highest production of CA (380 mg.L(-1)) was obtained when an intermediate concentration of 20 g.L(-1) of SPI (2.95 g.L(-1) total N) was used. To address this, the influences of volumetric flow rate (F) and glycerol concentration in the complex feed medium (Cs(F)) in fed-batch cultivations were investigated. The best experimental condition for CA production was F=0.01 L.h(-1) and Cs(F)=120 g.L(-1), and under these conditions maximum CA production was practically twice that obtained in the batch cultivation. A single empirical equation was proposed to relate maximum CA production with F and Cs(F) in fed-batch experiments.

Clavulanic acid (CA) is a powerful inhibitor of the beta-lactamases, enzymes produced by bacteria resistants to penicillin and cefalosporin. This molecule is produced industrially by strains of Streptomyces clavuligerus in complex media which carbon and nitrogen resources are supplied by inexpensive compounds still providing high productivity. The genetic production improvement using physical and chemical mutagenic agents is an important strategy in programs of industrial production development of bioactive metabolites. However, parental strains are susceptible to loss of their original productivity due genetic instability phenomenona. In this work, some S. clavuligerus mutant strains obtained by treatment with UV light and with MMS are compared with the wild type (Streptomyces clavuligerus ATCC 27064). The results indicated that the random mutations originated some strains with different phenotypes, most divergent demonstrated by the mutants strains named AC116, MMS 150 and MMS 54, that exhibited lack of pigmentation in their mature spores. Also, the strain MMS 150 presented a larger production of CA when cultivated in semi-synthetics media. Using other media, the wild type strain obtained a larger CA production. Besides, using the modifed complex media the MMS 150 strain showed changes in its lipolitic activity and a larger production of CA. The studies also allowed finding the best conditions for a lipase activity exhibited by wild type S. clavuligerus and the MMS150 mutant.

Lipases constitute an important group of biocatalysts for biotechnological applications. This enzyme can be produced by plants, animals, and microorganisms. However, microbial lipases are the most studied and occupy the center attraction because of their stability, selectivity, and broad substrate specificity. Streptomyces are filamentous Gram-positive bacteria found generally in the soil. This microorganism is known mainly for their capacity to synthesize of numerous antibiotics and other secondary metabolites. They also produce a large number of enzymes such as lipases, which makes Streptomyces a genus with significant biotechnological potential.

Streptomyces clavuligerus, initially described as a Cephamycin C producer, has been currently utilized to produce clavulanic acid (CA) which shows low antibiotic activity, being, however, a strong β-lactamase inhibitor, enzymes responsible for bacterial resistance to β-lactam antibiotics. Genetic improvement by physical and chemical agents is mandatory since, due to its genetic instability, industrial strains lose production capability making necessary a steady and frequent strain improvement and a screening procedure. The objective of this work was to obtain an increase in CA production in submerged cultures by utilizing mutants obtained by UV radiation of Original Research Articlewith this mutant, although a lower specific growth rate had been observed.

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