Screening of lysine production by Escherichia coli and Klebsiella isolates at different carbon sources

Lysine is an essential amino acid that is not biologically manufactured in the body. Different chemical methods for lysine production are expensive and give low yields. The present study was conducted with the purpose to evaluate the biochemical production of lysine by different carbon sources using bacterial isolates. Three carbon sources namely glucose, sucrose, and fructose were used to evaluate the biochemical production of lysine by Escherichia coli and Klebsiella spp. isolates. Optimum incubation periods were between 48-96 hours. An extensive amount of lysine was produced by all of these isolates in L6 fermentation medium. Maximum lysine was produced by Klebsiella isolate K1 6.48 g/L after 96 hours of incubation by using glucose as carbon source followed by 6.0 g/L by Klebsiella isolates K3 after 72 hours of incubation when sucrose was used as a carbon source at 37 °C. Highest amount of lysine was produced at 96 hours by Klebsiella isolates in addition to E. coli. From all three carbon sources using Klebsiella isolates and E. coli, glucose showed better lysine production.

Antibacterial and antibiofilm properties of traditional medicinal plant from Sheikh Buddin range.

During current project, antibacterial and antibiofilm properties of traditional medicinal plant Ziziphus nummularia leaf extract and various fractions was investigated. The plant leaves were dried and extracted using 90% methanol followed by sequential fractionation using liquid-liquid fractionation. The fractions of a diverse polarity including chloroform, n-hexane, methanol and ethyl acetate and aqueous extracts were obtained that was further analysed by using HPLC. The phytochemical screening indicated presence of saponins, triterpenes and flavonoids. During DPPH assay, the methanolic fraction presented highest activity (IC50 193.1µg/mL), followed by ethyl acetate (IC50 220µg/mL) and chloroform (IC50 263µg/mL) fractions respectively. During FRAP assay, FRAP value for Z. nummularia extract 20.43µM. Among fractions, ethyl acetate fraction presented highest FRAP value (370.2µM), followed by chloroform (204µM) and methanolic (249µM) fractions. The antimicrobial activity of chloroform fraction was significantly high against P. aureginosa (6mm), L. monocytogenes, S. aureus (5mm), K. pneumoniae, B. Subtillus and E. coli (4mm). The ethyl acetate part presented significant activity (MIC 4mg/mL) against S. aureus, B. Subtillus and L. monocytogenes. The total extract and fractions were further tested for MBC and the MBC for ethyl acetate fractions was 4mg/mL, whereas all other fractions exhibited MBC >10mg/mL. No activity was recorded against Aspergillus niger. During antibiofilm assay, n-hexane fraction presented highest inhibition (88%) followed by ethyl acetate (69%) chloroform (65%) fractions. It was concluded that Z. nummularia possess moderate antimicrobial and antibiofilm activities. Further a synergistic effect is suggested in formulation having Z. nummularia.