Yue-Horng Yen

Bioconversion of squid pen by Lactobacillus paracasei subsp paracasei TKU010 for the production of proteases and lettuce growth enhancing biofertilizers

A protease-producing bacterium, strain TKU010, was isolated from infant vomited milk and identified as Lactobacillus paracasei subsp. paracasei. A surfactant-stable protease, purified 64-fold from the third day culture supernatant to homogeneity in an overall yield of 11%, has a molecular weight of about 49,000. The enzyme degraded casein and gelatin, but did not degrade albumin, fibrin, and elastin. The enzyme activity was increased about 1.5-fold by the addition of 5mM Ba(2+). However, Fe(2+) and Cu(2+) ions strongly inhibited the enzyme. The enzyme was maximally active at pH 10 and 60 degrees C and retained 94% and 71% activity in the presence of Tween 20 (2% w/v) and SDS (2mM), respectively. The result of identification of TKU010 protease showed that nine tryptic peptides were identical to Serratia protease (serralysin) (GenBank accession number gi999638) with 35% sequence coverage. In comparison with the tryptic peptides of L. paracasei subsp. paracasei TKU012 protease, TKU010 protease possessed two additional peptides with sequences of AATTGYDAVDDLLHYHER and QTFTHEIGHALGLSHPGDYNAGEGNPTYR. The fourth day culture supernatant of TKU010 showed maximal activity of about 5-fold growth enhancing effect on lettuce weight, which was not shown with L. paracasei subsp paracasei TKU012.

Utilisation of chitinous materials in pigment adsorption

The effect of adding the cells of four lactobacilli to a squid pen powder (SPP)-containing medium on prodigiosin (PG) production by Serratia marcescens TKU011 is examined. The best increase in PG productivity was shown by strain TKU012. Among the samples of strain TKU012 and the chitinous materials of cicada casting powder (CCP), shrimp shell powder (SSP), squid pen powder (SPP), α-chitin, and β-chitin, TKU012 cells displayed the best adsorption rate (84%) for PG, followed by CCP, SSP, SPP, α-chitin, and β-chitin. As for the water-soluble food colourants, Allura Red AC (R40) and Tartrazne (Y4), SPP and SSP had better adsorptive powers than pure chitin preparations, strain TKU012, and CCP. Treatment with organic solvents, hot alkali, or proteases (papain, bromelain) diminished the adsorption rates of the biosorbents.

Enhancement of prodigiosin production by Serratia marcescens TKU011 and its insecticidal activity relative to food colorants.

Prodigiosin (PG) has been reported to have various biological activities. With the aim of increasing Serratia marcescens TKU011 PG production on squid pen powder (SPP)-containing medium, the effects of phosphate and ferrous ion supplementation, autoclave treatment, and aeration were studied. Autoclave treatment showed positive results for PG productivity (2.48 mg/mL), which increased 2.5-fold when the organism was incubated in 50 mL of 40-min autoclaved medium in a baffle-based flask (250 mL) containing 1.5% SPP at 30 °C for 1 day and then at 25 °C for 2 additional days. Furthermore, the use of pigments including PG and the food colorants Allura Red AC (R40) and Tartrazine (Y4) as insecticides was also investigated. The lethal concentrations causing 50% Drosophila larval mortality (LC50) of PG, Y4, and R40 using a 5-d exposure period were 230, 449, and 30000 ppm, respectively. The results indicated that the biopigment PG and the food colorant Y4 were potentially toxic to Drosophila larvae.