Estudo de caso: Análise de microrganismos produtores de ácido lácteo na produção de etanol

Abstract

Ethanol production from sugarcane faces significant challenges due to contamination by lactic acid bacteria (LAB), which compete with Saccharomyces cerevisiae yeast for substrates and produce lactic acid, reducing yields by up to 30%. This study analyzed microbial dynamics in a Brazilian Northeast ethanol plant, quantifying lactic acid and contaminating bacilli during fermentation. Microscopic counting methods revealed lactic acid concentrations between 2.04 and 4.32 g/L, linked to bacterial populations of 10⁶–10⁷ CFU/mL. Data showed that homofermentative strains were predominant, responsible for medium acidification and losses of R$ 2.7 million in 30 days. Strategies such as bacteriocide treatment, real-time pH sensor monitoring, and inoculation of acid-resistant yeast reduced contamination by 92%, recovering 87% of theoretical yield. Thus, combining robust microbiological controls with innovative technologies like DNA probe-equipped diagnostic sticks for rapid detection is crucial for industrial sustainability.