Comparison of Rhizopus Sp. and Lactobacillus Spp. Performance in Lactic Acid Fermentation of Sugar Palm (Arenga pinnata) Solid Waste

Abstract

Lactic acid is an important component of the manufacturing polylactic acid (PLA), which can produce by using high-lignocellulosic biomass (such as rice husk), The sugar palm (Arenga pinnata) industry produces an abundant amount of lignocellulosic solid waste. The poor utilization of sugar palm solid waste (SPSW) leads to its potential as a fermentation medium due to its reducing sugar content. Lactic acid fermentation is often conducted using lactic acid bacteria (LAB). However, filamentous fungi such as Rhizopus sp. also have the potential to produce lactic acid in fermentation. In the study, SPSW was pretreated using the acid-organosolv method. First, it was ground and screened up to 100-120 mesh. The output sample of the screener was pretreated chemically using dilute acid (H2SO4) with a solid-to-liquid ratio of 1:5 w/w for 40 minutes at 120°C and organosolv (ethanol 30%) with a solid: liquid ratio of 1:7 w/w for 33 minutes in 107°C. Enzymatic hydrolysis was performed using the cellulase enzyme. The fermentation was conducted using microorganisms of Rhizopus sp. (R. oryzae and R. arrhizus) and Lactobacillus spp. (L. casei and L. rhamnosus) at various fermentation temperatures. The fermentation results were analyzed, with the results showing that the lactic acid concentration produced using Lactobacillus sp. was higher (4.396 g/L for L. casei and 4.089 g/L L. rhamnosus) than that using Rhizopussp. (2.248 g/L for R. oryzae and 2.742g/L for R. arrhizus).