Longterm storage of post-packaged bread by controlling spoilage pathogens using Lactobacillus fermentum C14 isolated from homemade curd

Abstract

One potent lactic acid bacterial strain C14 with strong antifungal activity was isolated from homemade curd. Based on morphological as well as biochemical characters and 16S rDNA sequence homology the strain was identified as Lactobacillus fermentum. It displayed a wide antimicrobial spectrum against both Gram-positive and Gram-negative pathogenic bacteria, and also against number of food spoilage, plant and human pathogenic fungi. The cell free supernatant (CFS) of the strain C14 was also effective against the fungi tested. Inhibition of radial growth of Penicillium digitatum, Trichophyton rubrum and Mucor sp. was noticed in the presence of CFS of C14 even at low concentration (1%). More than 94.3 ± 1.6% and 91.5 ± 2.2% inhibition of conidial germination of P. digitatum and Mucor sp. were noticed in the presence of 10-fold-concentrated CFS of C14. Massive deformation of the fungal mycelia was observed by SEM studies, and losses of cellular proteins and DNA are also evident upon its treatment with C14. HPLC analysis revealed the presence of phenyl lactic acid, lactic acid along with some unidentified compounds in the antifungal extract. Challenge experiment showed immense potential of the strain C14 in preventing the spoilage of bread samples caused by Mucor sp. and Bacillus subtilis. The bread samples remained fresh upto 25 days even after inoculation with Mucor sp. (3.7 × 104 spores /ml) and B. subtilis (4.6 × 104 CFU /ml). Along with the antifungal properties, the isolated lactic acid bacterial strain also showed very good antioxidant activities. Unchanged level of liver enzymes serum glutamic pyruvic transaminase and serum glutamic oxaloacetic transaminase in albino mice upon feeding with C14 also suggested non-toxic nature of the bacterial isolate.

Isolation and Characterization of Lactic Acid Bacteria and Yeasts from Typical Bulgarian Sourdoughs

“…Sourdoughs are usually prepared by hand and there is a high risk of dough contamination with microorganisms from the environment and the personnel. B. subtilis is a typical contamination issue for the bread industry, especially during the warm seasons, since it decreases bread shelf life by causing the so-called “rope” of bread (stringy strands of mucilage, stickiness, unpleasant flavor and taste) [ 81 ], while Staphylococcus aureus (Gr+) and Salmonella enterica (Gr−) are common pathogens which may be transferred from the personnel during raw materials handling [ 82 ].…”

Probiotic cells support alginate‐based edible film properties: study of optical, water barrier and antifungal characteristics

“…4b). The antifungal action of lactic acid bacteria, including L. plantarum , Levilactobacillus brevis , Limosilactobacillus reuteri , Limosilactobacillus fermentum and L. buchneri strains, has been documented previously and corresponded to the production of acetic, lactic and phenyllactic acids (Gerez et al ., 2009; Barman et al ., 2017; Guimarães et al ., 2020; Abouloifa et al ., 2021). These organic compounds have been explained as having potential antifungal biopreservative activity in another investigation against Aspergillus fumigatus and Rhizopus stolonifer (Prema et al ., 2010).…”

A natural strategy to improve the shelf life of the loaf bread against toxigenic fungi: The employment of fermented whey powder

“…In particular, it is possible to show in the results that the strain of L. plantarum that produced the lowest amount of phenolic acids was strain CECT 220, considering that just four antimicrobial compounds were identified. Considering the compounds detected, we have to underline the importance from a microbiological point of view of hydroxybenzoic acid and dl ‐3‐phenyllactic acid (Barman et al ; Taofiq et al ).…”

“…In particular, Barman et al () studied growth reduction of Mucor sp., Penicillium digitatum and Trichophyton rubrum by using the CFS of L. plantarum at a concentration of 10 mg/mL. In addition, they evidenced the presence of lactic acid, phenyllactic acid and other compounds unidentified in CFS.…”