Journal of Microbiology

Journal Articles

Genome information of the cellulolytic soil actinobacterium Isoptericola dokdonensis DS-3 and comparative genomic analysis of the genus Isoptericola: Yurim Bae , Sujin Lee , Kitae Kim , Hyun-Kwon Lee , Soon-Kyeong Kwon , Jihyun F. Kim; J. Microbiol. 2021;59(11):1010-1018. Published online November 1, 2021; DOI: https://doi.org/10.1007/s12275-021-1452-6

Abstract: The actinobacterial group is regarded as a reservoir of biologically active natural products and hydrolytic enzymes with the potential for biomedical and industrial applications. Here, we present the complete genome sequence of Isoptericola dokdonensis DS-3 isolated from soil in Dokdo, small islets in the East Sea of Korea. This actinomycete harbors a large number of genes encoding carbohydrate-degrading enzymes, and its activity to degrade carboxymethyl cellulose into glucose was experimentally evaluated. Since the genus Isoptericola was proposed after reclassification based on phylogenetic analysis, strains of Isoptericola have been continuously isolated from diverse environments and the importance of this genus in the ecosystem has been suggested by recent culturomic or metagenomic studies. The phylogenic relationships of the genus tended to be closer among strains that had been isolated from similar habitats. By analyzing the properties of published genome sequences of seven defined species in the genus, a large number of genes for carbohydrate hydrolysis and utilization, as well as several biosynthetic gene clusters for secondary metabolites, were identified. Genomic information of I. dokdonensis DS-3 together with comparative analysis of the genomes of Isoptericola provides insights into understanding this actinobacterial group with a potential for industrial applications.

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.

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