Journal of Microbiology

Journal Article

Improved Production of Live Cells of Lactobacillus rhamnosus by Continuous Cultivation using Glucose-yeast Extract Medium: Liew Siew Ling , Rosfarizan Mohamad , Raha Abdul Rahim , Ho Yin Wan , Arbakariya Bin Ariff; J. Microbiol. 2006;44(4):439-446.; DOI: https://doi.org/2408 [pii]

Abstract: In this study, the growth kinetics of Lactobacillus rhamnosus and lactic acid production in continuous culture were assessed at a range of dilution rates (0.05 h?1 to 0.40 h?1) using a 2 L stirred tank fermenter with a working volume of 600 ml. Unstructured models, predicated on the Monod and Luedeking-Piret equations, were employed to simulate the growth of the bacterium, glucose consumption, and lactic acid production at different dilution rates in continuous cultures. The maximum specific growth rate of L. rhamnosus, ┢max, was estimated at 0.40 h?1, and the Monod cell growth saturation constant, Ks, at approximately 0.25 g/L. Maximum cell viability (1.3 ≠ 1010 CFU/ml) was achieved in the dilution rate range of D = 0.28 h?1 to 0.35 h?1. Both maximum viable cell yield and productivity were achieved at D = 0.35 h?1. The continuous cultivation of L. rhamnosus at D = 0.35 h?1 resulted in substantial improvements in cell productivity, of 267% (viable cell count) that achieved via batch cultivation.

Reduction of Hexavalent Chromium by Escherichia coli ATCC 33456 in Batch and Continuous Cultures: Woo Chul Bae , Tae Gu Kang , In Kyong Kang , You Jung Won , Byeong Chul Jeong; J. Microbiol. 2000;38(1):36-39.

Abstract: Toxic hexavalent chromium, Cr(VI), was reduced to a less toxic trivalent chromium form by E. coli ATCC 33456. The suitable electron donor for Cr(VI) reduction was glucose. E. coli ATCC 33456 was more resistant to metal cations than other reported Cr(VI) reducing microorganisms. Cell growth was inhibited by the presence of Cr(VI) in a liquid medium and Cr(VI) reduction accompanied cell growth. With a hydraulic retention time of 20 h, Cr(VI) reducing efficiency was 100% to 84% when Cr(VI) concentration in the influent was in the range of 10 to 40 mg L^-1. Specific rate of Cr(VI) concentration in the influent was 2.41 mg Cr(VI) g DCW^-1 h^-1 when 40 mg :^-1 of Cr(VI) influent was used. This result suggested the potential application of E. coli ATCC 33456 for the detoxification of Cr(VI) in Cr(VI) contaminated wastewater.

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