Screening for gum‐producing Lactic acid bacteria in Oil palm (Elaeis guineensis) and raphia palm (Raphia regalis) sap from South‐West Nigeria

Abstract

Lactic acid bacteria have wide applications in food processing. Lactic acid bacteria produced exopolysaccharides (EPS) which could be used as possible replacer for commercial stabilizer and thickeners produced by nonfood grade bacteria. Seventy‐two samples of Oil and Raphia palm sap were collected in eighteen locations across South‐Western Nigeria and screened for exopolysaccharide production in 6% sucrose agar using streaked plate method. Four hundred EPS‐producing bacteria (EPB) isolated were clustered based on morphological characteristics into two broad groups and preliminary screened for EPS‐producing capacity. Twenty representative of EPB were selected from the broad groups for tentative identification by API 50CHL and 10 high yielding EPB were selected for large‐scale EPS production. Each strain was inoculated into 6% sucrose broth with 3% (v/v) preculture grown overnight in a 1.5 ml flask and incubated at 37°C for 72 hr. The EPSs were purified and freeze‐dried prior to quantification of yields. EPS‐producing bacteria were identified as Leuconostoc lactis, Lactobacillus fermentum, Lactobacillus delbrueckii ssp. lactis, L. delbrueckii ssp. delbrueckii, Lactobacillus acidophilus, Lactobacillus plantarum, Lactobacillus crispatus, and Leuconostoc mesenteroides ssp. mesenteroides/dextranicum. EPS yield ranged from 132–810.75 mg/L and EPS‐producing potential of lactic acid bacteria (LAB) strains ranged; 36% (132–245 mg/L), 36% (250–460 mg/L), and 28% (461–820 mg/L). L. plantarum had the highest EPS yield of 810.75 mg/L whereas L. crispatus had the least yield 242.5 mg/L. These results suggest that majority of LAB in palm wine saps are gum‐producing bacteria. Leuconostoc and Lactobacillus were the most abundant LAB found in this study while L. plantarum could have applications as potential starter cultures for the production of exopolysaccharides (EPS) at industrial level.

Microbial Diversity and Metabolite Profiles of Palm Wine Produced From Three Different Palm Tree Species in Côte d’Ivoire

“…Our results support the earlier findings of different dominant lactic acid bacteria (LAB) species according to the palm tree species studied 4,6,41 . www.nature.com/scientificreports www.nature.com/scientificreports/ Lactic acid bacteria are responsible for the pH reduction through production of organic acids, which give a sour taste to the palm wine, and are also, associated with the aroma, consistency and colour of palm wine by the production of polysaccharides 16,42 . Indeed, one of the broadly recognized advantages of LAB along with acetic acid bacteria (AAB) in food fermentation is the inhibitory effect on foodborne pathogens particularly on the www.nature.com/scientificreports www.nature.com/scientificreports/ members of Enterobacteriaceae 43 , which could explain the very low relative occurrence (<1%) of the potential pathogenic members of Enterobacteriaceae in the palm wine samples studied, despite the poor hygienic production environment.…”

Dominance of Bacillus species in the wheat (Triticum aestivum L.) rhizosphere and their plant growth promoting potential under salt stress conditions

“…Bacterial colonies displaying different morphology were selected and subcultured until culture purity is confirmed. Bacterial cultures were streaked on LB agar plates and incubated for 24 h at 28 °C, and mucoid colonies were identified as gum production ( Adamu-Governor et al, 2018 ). Bacterial cell suspension was prepared in saline and observed for size and shape of bacteria under a light microscope.…”

Comparative Study of Commercial Starter and Gum-producing Lactic Acid Bacteria Isolated from Palm-sap on Yoghurt

“…delbrueckii ssp. and S. thermophilus in different quantities based on their biosynthesis capacity [11]. EPSs from LAB share the status of generally regarded as safe (GRAS) with LAB being the source.…”

“…The aim of this research was to comparatively determine the physicochemical, rheological, microbiological and sensory properties of fermented cow milk by using EPSproducing starter cultures and EPS, separately and in composite using a conventional starter, xanthan gum and commercial yoghurt as control. [11] were obtained from collections of the Molecular Biology laboratory unit, CCRL.…”