Authors: Modesto Millán, Daniel Gutierrez, Lourdes Rodriguez-Fragoso, Jorge Reyes-Esparza
Lactobacillus spp. are lactic acid bacteria (LAB) commonly found in the mammalian gut microbiota and Lactobacillus plantarum is a Gram-positive bacterium commonly found in fermented food and is classified as probiotic [1]. This probiotic-bacterium is wide applications in the medical field because present antioxidant, anticancer, anti-inflammatory, antiproliferative, anti-obesity and antidiabetic properties [2]. Probiotics are live microorganisms that when are administered in adequate amounts, confer a health benefit on the host [3]. Probiotics are wide used in applications of the pharma industry because contributing significantly to human medicine without contributing to any side effects.
However, there are not studies were the culture conditions in bioreactors have been evaluated and particularly, as the temperature, the pH and the stirring speed affected the growth of this probiotic-bacterium. This is an important field that needs to be investigated and by this reason the objective of this study was evaluated the effect of the temperature, the pH and the stirring speed on the viable biomass production in cultures of L. plantarum. The effect of temperature on biomass production of L. plantarum, was evaluated in 250 mL Erlenmeyer flasks cultures with 100 mL of MRS medium at 34, 37 and 40ºC. The maximum biomass concentration was of 3.72 ± 0.03 g L-1 in the temperature condition of 37°C. In bioreactor cultures, the maximum biomass concentration obtained was of 4.0 ± 0.1 g L-1 in the conditions evaluated of 100 and 300 rpm when the pH was kept constant at 5.0, meanwhile the cell viability was higher (2.73 ± 0.37 x 1010 CFU mL-1) compared with the cell viability obtained in conditions in which the pH was increased at 6.0 or 7.0 (8.0 ± 1.0 x 109
CFU mL-1). On the contrary, when the pH and stirring speed conditions were 7.0 and 300 rpm, the specific growth rate (μ) obtained was maximum (0.99 ± 0.01 h-1). In summary, the low pH conditions favored the biomass production and the cell viability in the cultures of probiotic-bacterium L. plantarum. However, the μ was favored in conditions of high of pH and stirring speed (7.0 and 300 rpm). With
these findings, is possible establishing adequate conditions for the production of L. plantarum viable biomass in bioreactor cultures for use as probiotic.