A total of 32 lactic acid bacteria (LAB) were isolated from 13 honey samples commercially marketed in Malaysia, 6 strains identified as Lactobacillus acidophilus by API CHL50. The isolates had antibacterial activities against multiple antibiotic resistant's Staphylococcus aureus (25 to 32 mm), Staphylococcus epidermis (14 to 22 mm) and Bacillus subtilis (12 to 19 mm) in the agar overlay method after 24 h incubation at 30 °C. The crude supernatant was heat stable at 90 °C and 121 °C for 1 h. Treatment with proteinase K and RNase II maintained the antimicrobial activity of all the supernatants except sample H006-A and H010-G. All the supernatants showed antimicrobial activities against target bacteria at pH 3 and pH 5 but not at pH 6 within 72 h incubation at 30 °C. S. aureus was not inhibited by sample H006-A isolated from Libyan honey and sample H008-D isolated from Malaysian honey at pH 5, compared to supernatants from other L. acidophilus isolates. The presence of different strains of L. acidophilus in honey obtained from different sources may contribute to the differences in the antimicrobial properties of honey.

Aspergillus flavus is a toxigenic fungus well known for the synthesis of aflatoxins that contaminate crops and food products. Antifungal peptides generated by lactic acid bacteria have a high potential for applications as bio-control agent to prolong the shelf life of crops. In this study, antifungal activity of peptides generated by Lactobacillus plantarum TE10 was tested against the spoilage fungi Aspergillus flavus MD3. L. plantarum TE10 was inoculated in MRS broth and incubated at 37 �C for 48 h and the antifungal activity was determined using dual agar overlay method. The cell free supernatant was fractionated using size exclusion chromatography, and the peptides were identified using LC-MS/MS. Scanning electron microscope was performed to determine the effects of the active fraction on the morphology of target fungi. The antifungal activity of the active fraction was further confirmed against selected fungi in fresh maize seeds. A total of 37 peptides were identified in fraction 7 that showed the highest antifungal activity. The peptides mixture in fraction 7 caused damage at the tip of the mycelia as observed by scanning electron microscope. Growth of A. flavus was observed after 7 days on the samples treated with distilled water and MRS broth, while slight growth was observed on the sample treated with fraction 7. Fraction 7 reduced the spore formation of A. flavus by 4 folds compared to the control. The results demonstrated promising application of the peptides mixture as bio-control agent to prevent the growth of A. flavus in maize. � 2019 Elsevier Ltd

Aspergillus flavus is a toxigenic fungus well known for the synthesis of aflatoxins that contaminate crops and food products. Antifungal peptides generated by lactic acid bacteria have a high potential for applications as bio-control agent to prolong the shelf life of crops. In this study, antifungal activity of peptides generated by Lactobacillus plantarum TE10 was tested against the spoilage fungi Aspergillus flavus MD3. L. plantarum TE10 was inoculated in MRS broth and incubated at 37 �C for 48 h and the antifungal activity was determined using dual agar overlay method. The cell free supernatant was fractionated using size exclusion chromatography, and the peptides were identified using LC-MS/MS. Scanning electron microscope was performed to determine the effects of the active fraction on the morphology of target fungi. The antifungal activity of the active fraction was further confirmed against selected fungi in fresh maize seeds. A total of 37 peptides were identified in fraction 7 that showed the highest antifungal activity. The peptides mixture in fraction 7 caused damage at the tip of the mycelia as observed by scanning electron microscope. Growth of A. flavus was observed after 7 days on the samples treated with distilled water and MRS broth, while slight growth was observed on the sample treated with fraction 7. Fraction 7 reduced the spore formation of A. flavus by 4 folds compared to the control. The results demonstrated promising application of the peptides mixture as bio-control agent to prevent the growth of A. flavus in maize. � 2019 Elsevier Ltd

In the search for new preservatives from natural resources to replace or to reduce the use of chemical preservatives 4 strains of lactic acid bacteria (LAB) were selected to be evaluated for their antifungal activity on selected foods. The supernatants of the selected strains delayed the growth of fungi for 23 to 40 d at 4 °C and 5 to 6 d at 20 and 30 °C in tomato puree, 19 to 29 d at 4 °C and 6 to 12 d at 20 and 30 °C in processed cheese, and 27 to 30 d at 4 °C and 12 to 24 d at 20 and 30 °C in commercial bread. The shelf life of bread with added LAB cells or their supernatants were longer than normal bread. This study demonstrates thatLactobacillus fermentumTe007,Pediococcus pentosaceusTe010,L. pentosusG004, andL. paracasiD5 either the cells or their supernatants could be used as biopreservative in bakery products and other processed foods. Practical Application: The heat stability nature of the antifungal compounds produced by the LAB isolates offers a promising application ofL. fermentumTe007,P. pentosaceusTe010,L. pentosusG004, andL. paracasiD5 as biopreservative in bakery products or other processed foods to replace or reduce the use of chemical preservatives.

Background: Despite the extensive research carried out to develop natural antifungal preservatives for food applications, there are very limited antifungal agents available to inhibit the growth of spoilage fungi in processed foods. Scope and Approach: Therefore, this review summarizes the discovery and development of antifungal peptides using lactic acid bacteria fermentation to prevent food spoilage by fungi. The focus of this review will be on the identification of antifungal peptides, potential sources, the possible modes of action and properties of peptides considered to inhibit the growth of spoilage fungi. Key Findings and Conclusions: Antifungal peptides generated by certain lactic acid bacteria strains have a high potential for applications in a broad range of foods. The mechanism of peptides antifungal activity is related to their properties such as low molecular weight, concentration and secondary structure. The antifungal peptides were proposed to be used as bio-preservatives to reduce and/or replace chemical preservatives. � 2020 Bentham Science Publishers.

Problem statement: This study reports the isolation of lactic acid bacteria from 13 honey samples produced in Malaysia, Libya and Saudi Arabia and their antibacterial activity against three Gram negative pathogenic bacteria. Approach: A modified MRS agar with 0.8% CaCO3 and MRS with 1% glucose was found to facilitate isolation of LAB compared to MRS, tomato juice agar and modified tomato juice agar. 32 isolates were confirmed LAB by catalase test and Gram staining. Six isolates were screened for antibacterial activity and identified as strains of Lactobacillus acidophilus 1 by API CH50. Results: All the isolates showed very good inhibitory activity against target Gram negative bacteria as indicated by the diameter of inhibition zone: Salmonella Typhimurium (23-30 mm), Escherichia coli (7-18 mm) and Enterobacter aerogenes (10-18 mm) after 24 h incubation at 30�C. Supernatants of L. acidophilus 1 strains showed good antibacterial activity against all target bacteria. Heating the supernatants at 90 and 121�C for 1 h enhanced the antibacterial activity against all target bacteria except supernatants H006-A and H010-G against S. Typhimurium. Antibacterial activity of supernatants were maintained after pH adjustment to 3, but at pH5 supernatants H006-A, H008-D and H010-G lost the activity against S. Typhimurium and E. coli within 48 h of incubation while at pH 6 all supernatants lost activity except against E. aerogenes. Enzymes treatments of supernatants with RNase II and Proteinase K for 1 h inhibited all target bacteria except supernatants H008-D, H008-E and H006-A which were relatively sensitive to both enzymes against S. Typhimurium and E. coli. Conclusion/Recommendations: In conclusion, honey from different sources contains strains of L. acidophilus 1 that produced compounds with good antibacterial activity which may be responsible for the antibacterial properties of honey. � 2012 Science Publications.

The use of secondary metabolites of lactic acid bacteria for preservation of foods is increasingly gaining interest to the food industry to replace synthetic preservatives. In this study, the cell free supernatant containing peptides obtained from Lactobacillus plantarum IS10 was fractionated by size exclusion chromatography using sephadex G-25, and tested against Aspergillus flavus MD3, Penicillium roqueforti MD4 and Eurotium rubrum MD5. Among the fractions, fraction number 10 showed 60% antifungal activity at a concentration of 0.02 mg peptide/mL. Four novel peptides out of twenty peptides obtained from fraction 10 were identified and determined by de novo sequencing. Peptide FPSHTGMSVPPP with a net charge +1, hydrophobicity ratio 58% and molecular weight of 1253 was further studied. The selected peptide showed a good activity at a concentration of 5 mg/mL against selected fungi and poor activity at low concentrations. This work indicates that L. plantarum IS10 has the capability of producing peptides which are affective against spoilage fungi. � 2015.

Bio-preservation, a promising preservation method that involves the use of “friendly” microorganisms such as lactic acid bacteria, has recently become a topic of considerable interest. In the present study, 16 lactic acid bacteria isolates were evaluated for antifungal activity against six fungi commonly associated with bread spoilage. The antifungal compounds were heat stable at 121 °C, and only four isolates, DU15, IT10, TE10, and IS10, showed partial loss of activity when supernatants were treated with proteolytic enzymes. The four isolates showed high inhibition activity at pH 3 and were identified using 16S rDNA sequencing as belonging to Leuconostoc mesenteroides DU15, Lactobacillus plantarum TE10, Lactobacillus plantarum IT10, and Lactobacillus plantarum IS10. The minimum germination inhibitions were 30 mg, 50 mg, 40 mg, and 50 mg for TE10, IT10, DU15, and IS10 respectively. The optimum conditions for the strains to produce antifungal compounds were 37 °C for 48 h for IT10, IS10, and TE10, and 30 °C for 24 h for DU15. Antifungal activity was increased threefold when supernatants were filtered using 10 KDa membranes. These findings demonstrate the potential of using lactic acid bacteria antifungal peptides as natural preservatives in bakery products to control the growth of spoilage fungi.

The ability of Leuconostoc mesenteroides DU15 to produce antifungal peptides that inhibit growth of Aspergillus niger was evaluated under optimum growth conditions of 30 °C for 48 h. The cell-free supernatant showed inhibitory activity against A. niger. Five novel peptides were isolated with the sequences GPFPL, YVPLF, LLHGVPLP, GPFPLEMTLGPT, and TVYPFPGPL as identified by de novo sequencing using PEAKS 6 software. Peptide LLHGVPLP was the only positively charged (cationic peptides) and peptide GPFPLEMTLGPT negatively charged (anionic), whereas the rest are neutral. The identified peptides had high hydrophobicity ratio and low molecular weights with amino acids sequences ranging from 5 to 12 residues. The mode of action of these peptides is observed under the scanning electron microscope and is due to cell lysis of fungi. This work reveals the potential of peptides from L. mesenteroides DU15 as natural antifungal preservatives in inhibiting the growth of A. niger that is implicated to the spoilage during storage.

Honey is rich with complex natural components which could be useful as antibacterial agents or as preservative. Honey contains high concentration of sugars, low amount of water, high osmolality and often dark colour which influence its antibacterial activity. Disc diffusion, well method, micro dilution assay are methods commonly used to determine the antibacterial activity of honey. In this study, microtiter and microbial plate count were included to ascertain the potency of honey as antibacterial agent against multiple antibiotic resistant pathogenic bacteria (Staphylococcus aureus, Salmonella Typhimurium, Escherichia coli, Bacillus subtilis and Pseudomonas aeruginosa) with concentration of 0.2 g mL-1. Results found that well diffusion method tends to give higher inhibitory zone than disc diffusion method but there was no correlation among the bacteria was observed except for S. Typhimurium, E. coli (R = 0.310, 0.505 and 0.316, respectively). Nan photometer assay and microtiter plates assay showed comparable results with moderately strong correlation (R2 = 0.681 and 0.767, respectively) for S. aureus and S. typhimurium, but poor correlation was found for E. coli, B. subtilis and P. aeruginosa (R2 = 0.441, 0.308 and 0.383, respectively). Determining the number of survivors by plating on agar after nanophotometer assay or microtiter plate assay had confirmed the effectiveness of honey as antimicrobial agent against target bacteria; which confirmed that honey has the potency to inhibit pathogens even at low concentration. � 2014 M.M. Aween et al.

Problem statement: The growth of spoilage fungi have been a global concern because of the economy loses and the health hazard of the mycotoxins produced by the spoilage fungi. Approach: A total of 137 lactic acid bacteria isolated from Malaysian fruits and fermented foods were screened for antifungal activity using dual agar overlay method and well method against A. oryzae. Results: 23 isolates showed inhibition activity after 72 h incubation at 30�C. Supernatant of three isolates with strong antifungal activity was evaluated by well method and they inhibited the growth of the fungi at 30�C for 72 h. LAB supernatant reduced the mass growth of Aspergillus oryzae when incubated for 7 days at 30�C. The isolates were identified using API 50CH as Lactobacillus brevis G004, Lactobacillus fermentum Te007 and Pediococcus pentosaceus Te010. Conclusion: The three isolates studied inhibited the growth of the mycelia and conidia germination of the fungi which indicate the possibility of using LAB isolates as biopreservative. � 2010 Science Publications.