Natural populations of lactic acid bacteria isolated from vegetable residues and silage fermentation

Abstract

Natural populations of lactic acid bacteria (LAB) and silage fermentation of vegetable residues were studied. Fifty-two strains of LAB isolated from cabbage, Chinese cabbage, and lettuce residues were identified and characterized. The LAB strains were gram-positive and catalase-negative bacteria, which were divided into 6 groups (A to F) according to morphological and biochemical characteristics. The strains in group A were rods that did not produce gas from glucose and formed the d and l isomers of lactate. Groups B and C were homofermentative cocci that formed l-lactic acid. Groups D, E, and F were heterofermentative cocci that formed d-lactic acid. Based on 16S rDNA gene sequence analysis, group A to F strains were identified as Lactobacillus plantarum, Lactococcus piscium, Lactococcus lactis, Leuconostoc citreum, Weissella soli and Leuconostoc gelidum, respectively. The prevalent LAB, predominantly homofermentative lactobacilli, consisted of Lactobacillus plantarum (34.6%), Weissella soli (19.2%), Leuconostoc gelidum (15.4%), Leuconostoc citreum (13.5%), Lactococcus lactis (9.6%), and Lactococcus piscium (7.7%). Lactobacillus plantarum was the dominant member of the LAB population in 3 types of vegetable residues. These vegetable residues contained a high level of crude protein (20.2 to 28.4% of dry matter). These silages prepared by using a small-scale fermentation system were well preserved, with low pH and a relatively high content of lactate. This study suggests that the vegetable residues contain abundant LAB species and nutrients, and that they could be well preserved by making silage, which is a potentially good vegetable protein source for livestock diets.

Identification of Lactic Acid Bacteria in Fruit Pulp Processing Byproducts and Potential Probiotic Properties of Selected Lactobacillus Strains

“…In addition to the known potential use of tropical fruit pulps and their byproducts for the isolation of phytochemicals for application in nutraceutical supplements (Ayala-Zavala et al, 2011), these byproducts also exhibit a wide variety of microorganisms of interest to the food industry (Yang et al, 2010), especially lactic acid bacteria (LAB). Each particular type of fruit provides a unique environment in terms of chemical composition, buffering capacity, competitive microbiota, and natural antagonist compounds (Naeem et al, 2012).…”

Classification of Lytic Bacteriophages Attacking Dairy Leuconostoc Starter Strains

“…In nature, leuconostocs preferably grow on vegetables (e.g., cabbage), pasture, and silage and are also part of the microflora of raw milk (2)(3)(4)(5). Milk, however, is not an optimal growth medium for leuconostocs, since they do not possess efficient proteolytic systems (1,6).…”

Quantifying Variability in Growth and Thermal Inactivation Kinetics of Lactobacillus plantarum

“…Eight pH values, namely, 7.0, 6.0, 5.0, 4.0, 3.6, 3.5, 3.4, and 3.3, were selected to test the effect of pH on the maximum specific growth rate ( max ) of L. plantarum. For each experiment, the MRS broth was buffered using 100 mM sodium phosphate buffer (1 M Na 2 HPO 4 and 1 M NaH 2 PO 4 [both from Merck KGaA, Darmstadt, Germany]). Because only the effect of pH was considered, 1 M sulfuric acid (Riedel-de Haën, Seelze, Germany) (8) was used to adjust the pH of the medium.…”