Identification of Lactobacillus Strains Capable of Fermenting Fructo-Oligosaccharides and Inulin

Novel probiotic strains that can ferment prebiotics are important for functional foods. The utilization of prebiotics is strain specific, so we screened 86 Lactobacillus strains and compared them to Bifidobacterium breve 2141 for the ability to grow and produce SCFA when 1% inulin or fructo-oligosaccharides (FOS) were provided as the carbon source in batch fermentations. When grown anaerobically at 32 °C, ten Lactobacillus strains grew on both prebiotic substrates (OD600 ≥ 1.2); while Lactobacillus coryniformis subsp. torquens B4390 grew only in the presence of inulin. When the growth temperature was increased to 37 °C to simulate the human body temperature, four of these strains were no longer able to grow on either prebiotic. Additionally, L. casei strains 4646 and B441, and L. helveticus strains B1842 and B1929 did not require anaerobic conditions for growth on both prebiotics. Short-chain fatty acid analysis was performed on cell-free supernatants. The concentration of lactic acid produced by the ten Lactobacillus strains in the presence of prebiotics ranged from 73–205 mM. L. helveticus B1929 produced the highest concentration of acetic acid ~19 mM, while L. paraplantarum B23115 and L. paracasei ssp. paracasei B4564 produced the highest concentrations of propionic (1.8–4.0 mM) and butyric (0.9 and 1.1 mM) acids from prebiotic fermentation. L. mali B4563, L. paraplantarum B23115 and L. paracasei ssp. paracasei B4564 were identified as butyrate producers for the first time. These strains hold potential as synbiotics with FOS or inulin in the development of functional foods, including infant formula.

Penghasilan Asid Laktik D daripada Hidrolisat Sabut Kelapa Tua dan Muda

Penghasilan asid laktik D semakin mendapat perhatian kerana sifat polimernya, poli asid laktik D, yang termostabil. Kajian ini dijalankan untuk menghasilkan asid laktik D daripada sisa pertanian yang tidak bernilai tinggi seperti sabut kelapa tua (SKT) dan sabut kelapa muda (SKM) melalui teknologi fermentasi. Peringkat pertama kajian, SKTdan SKM dikenakan pra-rawatan beralkali menggunakan 5% larutan natrium hidroksida pada suhu 121 °C selama 15 minit untuk menyingkirkan komponen lignin dan hemiselulosa. Kemudian, dua kaedah hidrolisis dikaji, iaitu hidrolisis berenzim dengan menggunakan enzim Acellerase 1500 (1, 5 dan 10%, i/i) dan hidrolisis berasid dengan menggunakan asid sulfurik (1, 3 dan 5%, i/i). Keputusan menunjukkan hidrolisis berenzim dengan kepekatan 10% enzim Accellerase 1500 (11.09 mg/mL) lebih cekap menukarkan selulosa kepada gula penurun berbanding hidrolisis berasid (0.87 mg/mL) dalam hidrolisat SKT. Manakala, bagi hidrolisat SKM, 5% enzim Accellerase menghasilkan kepekatan gula penu-run yang lebih tinggi berbanding hidrolisis berasid dengan 15.00 dan 1.02 mg/mL. Kadar penukaran gula penurun yang maksimum didapati daripada hidrolisis berenzim SKT dan SKM dengan 55% dan 60%. Pada peringkat kedua, hidrolisat yang mengandungi gula penurun yang tinggi digunakan sebagai sumber karbon untuk penghasilan asid lak-tik D oleh Lactobacillus coryniformis subsp. torquen melalui proses fermentasi (48 jam, 37 ºC, 150 rpm). Pada akhir proses fermentasi, sebanyak 4.93 g/L penghasilan asid laktik D direkodkan dalam kaldu hidrolisat SKT dan 3.98 g/L asid laktik D terhasil dalam kaldu hidrolisat SKM dengan pH kaldu fermentasi tidak dikawal. Kesimpulannya, selulosa dalam kedua-dua sampel SKT dan SKM boleh diuraikan kepada gula penurun melalui hidrolisis berenzim dan seterus-nya berpotensi untuk digunakan sebagai substrat bagi menghasilkan asid laktik D melalui proses fermentasi.

Probiotic potential of lactic acid bacteria obtained from fermented curly kale juice

The aim of the paper was to analyse changes in lactic acid bacteria (LAB) populations during spontaneous fermentation of green curly kale juice (Brasicca oleracea L. var. acephala L.) and to determine the probiotic potential of LAB isolates. The analyses revealed that changes in LAB populations were specific for spontaneously fermented vegetable juices. The initial microbiota, composed mostly of Leuconostoc mesenteroides bacteria, was gradually replaced by Lactobacillus species, mainly Lactobacillus plantarum, Lactobacillus sakei, and Lactobacillus coryniformis. Screening tests for the antimicrobial properties and antibiotic susceptibility of isolates allowed for the selection of 12 strains with desirable characteristics. L. plantarum isolates were characterized by the widest spectrum of antimicrobial interactions, both towards Gram-positive and Gram-negative bacteria. Also, L. plantarum strains exhibited the best growth abilities under low pH conditions, and at different NaCl and bile salt concentrations. All strains showed different levels of antibiotic sensitivity, although they were resistant to vancomycin and kanamycin. The present study has shown that bacterial isolates obtained from spontaneously fermented kale juice could constitute valuable probiotic starter cultures, which may be used in fermentation industry.

In Vitro Antimicrobial and Antioxidant Activities of Lactobacillus coryniformis BCH-4 Bioactive Compounds and Determination of their Bioprotective Effects on Nutritional Components of Maize (Zea mays L.)

Lactic acid bacteria (LAB) can synthesize antimicrobial compounds (AMCs) with nutritional and bioprotective properties in crops and food products. In the current study, AMCs of Lactobacillus coryniformis BCH-4 were evaluated to control fungal spoilage in maize grains. On maize grains treated with 75%–100% (v/v) concentrated AMCs, no fungal growth was observed even after 72 h of Aspergillus flavus inoculation. Proximate analysis of treatments A1 (raw grains), A2 (A. flavus inoculated grains) and A3 (A. flavus + AMCs inoculated grains) revealed that moisture was significantly (p ≤ 0.05) high in A2 than A3 and A1. Meanwhile, protein, fat, fiber and ash contents were significantly decreased in A2 compared to A1 and A3. Moreover, β-carotene contents were not statistically different between A1 and A3, while in A2 it was significantly decreased. HPLC analysis revealed the presence of 2-oxopropanoic acid, 2-hydroxypropane-1,2,3-tricarboxylic acid, 2-hydroxybutanedioic acid, 2-hydroxypropanoic acid, propanedioic acid and butanedioic acid, which also showed antifungal activity against Aspergillus flavus. FTIR spectroscopy revealed the presence of hydroxyl, carbonyl and ester-groups along with organic and fatty acids, thereby indicating their participation in inhibitory action. Furthermore, the AMCs were found to be a good alternative to chemical preservatives, thereby not only preserving the nutritive qualities but increasing the shelf life as well.