An Improved Test to Study the Changes in Membrane Permeability During Rehydration of Freeze-Dried Weissella paramesenteroides LC11

peer reviewedThe objective of this study was to assess changes in membrane permeability during rehydration of freeze-dried Weissella paramesenteroides LC11. Viability was assessed using the electrical conductivity measurement (ms cm-1 g-1 dry weight) and the plate count method (cfu g-1 dry weight). The symptoms of injury included an increase in the electrolyte leakage during the first 4 h of rehydration in Milli Q water and a decrease in the survival rate (about 64%), suggesting an increase in membrane permeability during dehydration. During rehydration of the freeze-dried strain, an increase in the temperature, NaCl or monosodium glutamate concentration and a decrease in H+ concentration resulted in an increase in the electrolyte leakage and a decrease in the survival rate (from about 5% to 97%, with respect to the treatment made). However, a decrease in the electrolyte leakage was observed with increasing glycerol, sucrose or maltodextrin and resulted in the maintenance of cell viability. Change in membrane permeability might lead to electrolyte leakage during rehydration and, ultimately, cell death. The electrolyte leakage assay associated with the plate count method, a quick and inexpensive method, could be used to evaluate dried bacteria resistance to dehydration

Send Orders for Reprints to [email protected] The Use of MALDI-TOF Mass Spectrometry, Ribotyping and Phenotypic Tests to Identify Lactic Acid Bacteria from Fermented Cereal Foods in Abidjan (Côte d'Ivoire)

Abstract: Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) protein analysis, automated ribotyping, and phenotypic tests (e.g., cell morphology, gas production from glucose, growth and acid production on homofermemtative-heterofermentative differential (HHD) agar medium, sugar fermentation patterns) were used to identify 23 lactic acid bacteria (LAB) isolated from fermented cereal foods available in Abidjan, Côte d'Ivoire. Pediococcus acidilactici (56.5%), Lactobacillus fermentum (30.4%), L. salivarius (4.3%), P. pentosaceus (4.3%) and L. plantarum subsp. plantarum (4.3%) were the species and subspecies identified. Protein based identification was confirmed by automated ribotyping for selected isolates and was similar to that provided by the phenotypic characterization. MALDI-TOF MS protein analysis provided a high level of discrimination among the isolates and could be used for the rapid screening of LAB starter cultures

Production of freeze-dried lactic acid bacteria starter culture for cassava fermentation into gari.

peer reviewedSixteen lactic acid bacteria, eight Lactobacillus plantarum, three L. pentosus, 2 Weissella paramesenteroides, two L. fermemtum and one Leuconostoc mesenteroides ssp. mesenteroides were previously isolated from cassava fermentation and selected on the basis of their biochemical properties with a view to selecting appropriate starter cultures during cassava fermentation for gari production. In this study, the potential of these pre-selected strains as suitable freeze-dried cultures was evaluated. Their ability to tolerate the freeze-drying process was assessed by dehydration in a glycerol solution of increasing concentration, followed by staining with two fluorescent markers: rhodamine 123 and propydium iodide. Twelve strains that recovered more than 50% of their population value after visualisation on an epi-fluorescent microscope were produced in a bioreactor and freeze-dried. The technological characteristics identified after the freeze-drying process, were a high cell concentration or high survival rate. The ability of the freeze-dried strains to recover their acidification activity was evaluated through the determination of the pH, titratable acidity (% lactic acid/g Dry Weight) and cell count over 24 h on MRS broth. Ultimately, the strains L. plantarum VE36, G2/25, L. fermentum G2/10 and W. paramesenteroides LC11 were selected to be developed as freeze-dried starter cultures for gari production

Continuously Dynamic Mixing (CDM) Method and Greenhouse Salt Tunnel (GST) TECHNOLOGY for Sea Salt Production Throughout the Year [Metode Continuously Dynamic Mixing (CDM) Dan Teknologi Greenhouse Salt Tunnel (GST) Untuk Produksi Garam Sepanjang Tahun]

Salah satu tantangan terbesar dalam produksi garam adalah kondisi cuaca yang tidak menentu ataupun tidak mendukung proses pengkristalan garam. Proses pembuatan garam yang sangat tergantung pada laju evaporasi membuat produksi garam akan berhenti pada musim hujan. Strategi pengoptimalan laju evaporasi dengan menggunakan rumah kristalisasi garam berkembang menjadi salah satu alternatif metode untuk mengatasi permasalahan tersebut. Studi ini bertujuan untuk mengembangkan teknologi produksi garam di musim hujan dengan menerapkan metode Continuously Dynamic Mixing (CDM) pada rumah kristalisasi berbentuk Greenhouse Salt Tunnel (GST). Penerapan metode CDM dalam teknologi GST merupakan inovasi teknologi yang dikembangkan khusus oleh peneliti dalam studi ini. Parameter lingkungan yang diteliti terdiri dari suhu harian (air dan udara), kecepatan angin, laju penguapan, kelembaban udara dan nilai skala Baumé dari air bahan baku garam. Kualitas produksi garam dievaluasi berdasarkan kandungan air dan kandungan NaCl. Hasil penelitian ini mengindikasikan kalau penerapan metode CDM pada GST membuat produksi garam yang dimulai dari air muda (± 2° Be) dapat dilakukan pada musim hujan. Garam yang dihasilkan berwarna putih dengan kandungan NaCl dan kadar air, secara berturut-turut, adalah 98.05 % dan 7 %. Hasil produksi garam per siklus produksi dalam musim hujan (15 hari) sebesar 300 kg/GST-Kristalisasi (luasan 44 m2). Berdasarkan hasil penelitian, metode CDM pada teknologi GST membuat produksi garam pada musim hujan sehingga produksi garam dapat dilakukan sepanjang tahun

Survival of Freeze-dried Leuconostoc mesenteroides and Lactobacillus plantarum Related to Their Cellular Fatty Acids Composition during Storage

Lactic acid bacteria strains Lactobacillus plantarum CWBI-B534 and Leuconostoc ssp. mesenteroïdes (L. mesenteroïdes) Kenya MRog2 were produced in bioreactor, concentrated, with or without cryoprotectants. In general, viable population did not change significantly after freeze-drying (p>0.05). In most cases, viable population for cells added with cryoprotectants was significantly lower than those without (p<0.05). Cellular fatty acids (CFAs) from the two strains in this study were analyzed before and after freeze-drying. Six CFAs were identified, namely, palmitic (C16:0), palmitoleic (C16:1), stearic (C18:0), oleic (C18:1), linoleic (C18:2), and linolenic (C18:3) acids were identified. Four of them, C16:0, C16:1, C18:0, and C18:1, make up more than 94% or 93% of the fatty acids in L. mesenteroides and L. plantarum, respectively, with another one, namely, C18:3, making a smaller (on average 5–6%, respectively) contribution. The C18:2 contributed very small percentages (on average≤1%) to the total in each strain. C16:0 had the highest proportion at most points relative to other fatty acids. Moisture content and water activity (a w) increased significantly during the storage period. It was observed that C16:1/C16:0, C18:0/C16:0 and C18:1/C16:0 ratios for freeze-dried L. mesenteroides or L. plantarum, with or without cryoprotectants, did not change significantly during the storage period. According to the packaging mode and storage temperatures, C18:2/C16:0 and C18:3/C16:0 ratios for freeze-dried L. mesenteroides and L. plantarum with or without cryoprotectants decreased as the storage time increased. However, a higher C18:2/C16:0 or C18:3/C16:0 ratio for L. mesenteroides and L. plantarum was noted in the freeze-dried powder held at 4 °C or under vacuum and in dark than at 20 °C or in the presence of oxygen and ligh