Isolation, Preparation and Characterization of Polylactic Acid Film Reinforced with Nano silica

Lactic acid was isolated by using microbial fermentation in whey media which was carried out by local strain Lactobacillus paraplantarum then polymerized using the acidic medium’s polycondensation method. FTIR and H-NMR were used to characterize the isolated lactic acid monomer and polyalctic acid (PLA), and the results confirmed the chemical structures of the isolated lactic acid and PLA. GPC techniques were used to determine the molecular weight and molecular weight distribution of the prepared PLA; the result showed that the Polydispersity index (PDI) was 2.51. The Biodegradable composite films of poly lactic acid (PLA)/Nano silica powder were prepared by the composite film casting method using dichloromethane as solvent. In contrast, Nano silica was synthesis from hydrolysis of tetra ethoxysilane and was loaded in PLA in 1 to5 wt. %. The films were subjected to a tensile strength study. Thermogravimetric analysis (TGA) and differential thermal analysis (DSC) were used to evaluate PLA. Also, water absorption of the prepared composites was studied, and the result showed that the thermal stability and water absorption of these prepared films were increased with an increasing percentage of Nano silica, while the percentage of crystallinity of the PLA evaluated from DSC was 28 %.

A comparative account of biogenic synthesis of silver nanoparticles using in-house potential probiotics and their antimicrobial activity against challenging antibiotic resistant pathogens

The present work focusses on development of a safe, inexpensive, and more accessible source for biosynthesis of silver nanoparticles. Four different in-house probiotic isolates i.e., Lactobacillus pentosus S6, Lactobacillus plantarum F22, Lactobacillus crustorum F11 and Lactobacillus paraplantarum KM1 isolated from different food sources, were used in the current study to check their ability to synthesize silver nanoparticles. All the probiotics synthesized silver nanoparticles shows maximum Surface Plasmon Resonance (SPR) at a peak of 450 nm, which confirms the formation of silver nanoparticles. Scanning Electron Microscopy (SEM) analysis identified the shape and distribution of silver nanoparticles. Transmission Electron Microscopy (TEM) revealed the average size of synthesized nanoparticles in the range of 10-50 nm, with smallest size of 5 nm for silver nanoparticles synthesized by L. crustorum F11. Further, Fourier-transform infrared spectroscopy (FTIR) detected the presence of different functional groups responsible for reduction of silver ion to form silver nanoparticles. The antimicrobial activity of these AgNP was also found to be effective against different bacterial and fungal pathogens viz. antibiotic resistant Staphylococcus aureus, Bacillus cereus, Listeria monocytogenes , Pythium aphanidermatum , Fusarium oxysporum and Phytopthora parasitica . However, L.crustorum F11 synthesized AgNP showed maximum inhibition against all the bacterial and fungal pathogens, with highest against S. aureus (20 0.61mm) and F. oxysporum (23 ). Findings from this study provide a durable and ecofriendly method for the biosynthesis of silver nanoparticles, having strong antimicrobial activity against different multidrug resistant microorganisms.

Microbiota “Fingerprint” of Greek Feta Cheese through Ripening

Feta is a Greek protected designation of origin (PDO) brined curd white cheese made from small ruminants’ milk. In the present research, Greek Feta cheese bacterial diversity was evaluated via matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS). Analysis of 23 cheese samples, produced in different regions of the country, was performed in two ripening times (three or six months post-production). The identified microbiota were primarily constituted of lactic acid bacteria. A total of 13 different genera were obtained. The dominant species in both ripening times were Lactobacillus plantarum (100.0% and 87.0%, at three or six months post-production, respectively), Lactobacillus brevis (56.5% and 73.9%), Lactobacillus paracasei (56.5% and 39.1%), Lactobacillus rhamnosus (13.0% and 17.4%), Lactobacillus paraplantarum (4.3% and 26.1%), Lactobacillus curvatus (8.7% and 8.7%). Other species included Enterococcus faecalis (47.8% and 43.5%), Enterococcus faecium (34.8% and 17.4%), Enterococcus durans (13.0% and 17.4%), Enterococcus malodoratus (4.3% and 4.3%), and Streptococcus salivarius subsp. thermophilus (21.7% and 30.4%). The increased ripening time was found to be correlated to decreased total solids (r = 0.616; p = 0.002), protein (r = 0.683; p < 0.001), and PH (r = 0.780; p < 0.001). The results of this study contribute to a better understanding of the core microbiota of Feta cheese.

Metabolic Profiles of Lactobacillus paraplantarum in Biofilm and Planktonic States and Investigation of its Intestinal Modulation and Immunoregulation in Dogs

The use of probiotics has recently become a considerably promising research area. The most advanced fourth-generation probiotics involve beneficial bacteria enclosed in biofilms. However, differences in the effects of probiotics...

Purification and characterization of novel exopolysaccharides produced from Lactobacillus paraplantarum KM1 isolated from human milk and its cytotoxicity

Background Microbial origin polysaccharides have gained popularity due to lesser toxicity, better degradability and selectivity as compared to their synthetic counterparts and can be used as emulsifier, stabilizer, thickener, texturizer, flocculating and gelling agent. Here main emphasis on exopolysaccharide production from potential lactic acid bacteria that has GRAS status. Results This work was aimed at isolating, purifying and characterizing an extracellular polysaccharide (EPS) produced by a foodgrade lactic acid bacteria Lactobacillus paraplantarum KM1. L. paraplantarum KM1 was isolated from human milk and identified by conventional and molecular techniques. The 16S rRNA sequence of the isolate was registered in National Centre for Biotechnology Information (NCBI) under accession number KX671558. L. paraplantarum KM1 was found to produce EPSs in lactose containing MRS medium, and the maximum yield (47.4 mg/ml) was achieved after 32-h incubation. As evident from TLC and HPLC analyses, the polysaccharide was found to be a heteropolymer-containing glucose, galactose and mannose as main sugars. Different oligosaccharides namely hexoses were obtained after partial hydrolysis of the polymer using MALDI-ToF-MS. The total molecular weight of all polysaccharides present was 348.7 kDa with 100 °C thermal stability as well as water soluble in nature. Cell cytotoxicity revealed that the purified EPS was safe for consumption; thus, it can be used in various food industries as emulsifying and texture agent. Conclusions The present study highlighted that exopolysaccharides could be harnessed to improve food products in terms of texture, emulsifying agents, pharmaceutical industry (antioxidants, antitumour, anti-inflammatory and antiviral agents) and as safety purposes.

Evaluation and Application of Different Cholesterol-Lowering Lactic Acid Bacteria as Potential Meat Starters

ABSTRACT A total of 115 isolates of lactic acid bacteria were screened from traditional fermented foods in Guizhou Province, People's Republic of China. The cholesterol removal rates of 86 isolates ranged from 7.29 to 25.66%, and 18 isolates showed a cholesterol removal rate of more than 15%. According to the results of physiological and biological tests, 13 isolates were selected to determine the fermentation performance; 9 isolates—MT-4, MT-2, PJ-15, SR2-2, SQ-4, SQ-7, ST2-2, ST2-6, and NR1-7—had high tolerance of bile salt and acid and had a survival rate of more than 96% under pH 3.0 and 0.3% bile salt. ST2-2, SR2-2, NR1-7, SQ-4, and MT-4 had high survival rate in different concentrations of NaCl and NaNO2 under different temperatures. According to BLAST comparison results of the 16S rRNA sequence in the GenBank database and the genetic distance of the 16S rRNA sequence with an ortho-connected algorithm, SR2-2, NR1-7, and ST2-2 were identified as Lactobacillus plantarum, MT-4 was identified as Lactobacillus pentosus, and SQ-4 was identified as Lactobacillus paraplantarum. Moreover, strains SQ-4 and MT-4 were added to fermented beef. Results showed that the fermented beef had delicious taste and was popular to consumers because of its proper pH, pleasant colors, high viable cell count, and suitable content of bound and immobilized water. These results provide a basis for the development of new starter formulation for the production of high-quality fermented meat products. HIGHLIGHTS

Lactobacillus garii sp. nov., isolated from a fermented cassava product

A novel Gram-positive, catalase negative, rod-shaped strain, FI11369T, was isolated from gari, a traditional West African fermented food derived from cassava. Based on 16S rRNA gene sequence similarity, the closest type strains were Lactobacillus xiangfangensis LMG 26013T (99.4 % similarity), Lactobacillus plajomi NBRC 107333T (99.1 %), Lactobacillus paraplantarum DSM 10667T (99.1 %), Lactobacillus pentosus DSM 20314T (99.0 %), Lactobacillus plantarum subsp. plantarum ATCC 14917T (99.0 %), Lactobacillus modestisalitolerans NBRC 107235T (98.9 %), Lactobacillus plantarum subsp. argentoratensis DSM 16365T (98.9 %) and Lactobacillus daowaiensis NCIMB 15183T (98.8 %). The genome of strain FI11369T was sequenced and the average nucleotide identity (ANI) was compared with its closest relatives. ANI analysis showed that the closest relative, L. xiangfangensis DSM 27103T, had only a 82.4 % similarity. The main fatty acids of FI11369T were saturated C16 : 0 (18.2 %), unsaturated C18 : 1 ω9c (43.8 %) and cyclopropane C19 : 0 cyclo (ω10c and/or ω6; 22.5 %). Based on the genotypic and phenotypic data obtained in this study, a novel Lactobacillus species, Lactobacillus garii sp. nov., with the type strain FI11369T (=NCIMB 15148=DSM 108249), is proposed.