Usage of ectoine as a cryoprotectant for cryopreservation of lactic acid bacteria.

Streptococcus thermophilus, the only Streptococcus species considered "Generally Recognized Safe", has been used widely in the food industry. This bacterium is one of the most valuable industrial lactic acid bacterial species. Due to the importance of this bacterium in industrial applications, it should be stored for a long time without losing its metabolic properties. The present study aimed to investigate the cryoprotectant effect of three compatible solutes (ectoine, trehalose, and sucrose) on bacterial cells stored at different temperatures (frozen at -80 °C or freeze-dried and subsequently stored at +4, -20, and -80 °C) for three months. The bacterial cells were tested for cell viability, bile salt tolerance, and lactic acid production before and after processing. The highest cell viability, bile salt tolerance, and lactic acid production were obtained with ectoine and under frozen (storage at -80 °C) conditions. In freeze-dried and subsequently stored at various temperatures, the best preservation was obtained at -80 °C, followed by -20 °C and +4 °C. Moreover, when ectoine's preservation potential was compared to other cryoprotectants, ectoine showed the highest preservation, followed by trehalose and sucrose. Although ectoine has a variety of qualities that have been proven, in the current work, we have shown for the first time that ectoine has cryoprotectant potential in yogurt starter cultures (S. thermophilus).

First determination of some phenolic compounds and antimicrobial activities of Geranium ibericum subsp. jubatum: A plant endemic to Turkey.

This paper includes the results of the first study about the phenolic characteristics and antimicrobial analyses of Geranium ibericum subsp. jubatum species found in Turkey . In the present work, the phenolic contents of different parts of the G. ibericum (flower, root, leaf) were determined with high-performance liquid chromatography (HPLC)-DAD (diode-array detector) and liquid chromatography (LC)-MS/MS (mass spectrometry). The following phenolic compounds were investigated: catechin, protocatechuic acid, gallic acid, ellagic acid, chlorogenic acid, 4-hydroxybenzaldehyde, p -coumaric acid, rutin, naringenin, kaempferol . Based on the results obtained, the roots and flowers of the plant are found to be very rich in ellagic acid (3473.57 µg g-1 dry plant) and catechin (2228.76 µg g-1 dry plant). The amount of chlorogenic acid (54.570 µg g-1 dry plant) is also high in the roots. The amounts of protocatechuic acid (122.5 µg g-1 dry plant) and gallic acid (725.34 µg g-1 dry plant) are high in the leaves. In addition, the total extract of G. ibericum obtained from leaf, flower, and root was tested against 6 gram-negative bacteria and Candida albicans . The G. ibericum extract was nearly as effective as commercial antibiotics at some concentrations (500-750 µg µL-1) for Acinetobacter baumannii , Klebsiella pneumonia , Proteus mirabilis , and Bacillus cereus .

Potential Plant Growth-Promoting Bacteria with Heavy Metal Resistance.

Plant growth-promoting (PGP) bacteria commonly have many strategies to cope with heavy metal toxicity. Heavy metal-resistant PGP bacteria can be used to improve the growth of plants in heavy metal contaminated soils. In this study, the soil samples were collected from the lead-zinc mineral deposits in Gümüshane Province, Turkey. Nine bacterial isolates were obtained on the nutrient agar medium supplemented with 100 mg/mL zinc and lead. All of the isolates were screened in terms of plant growth-promoting characteristics including production of indole-3-acetic acid and siderophore, nitrogen fixation and phosphate solubilisation. Nine bacteria were identified as Bacillus cereus, Bacillus atrophaeus, Bacillus pumilus, Bacillus amyloliquefaciens, Bacillus tropicus, Bacillus subtilis, Bacillus halotolerans, Bacillus vallismortis, and Enterococcus mundtii by classical and 16S rDNA-PCR assays. In addition, these isolates were evaluated for their response to three heavy metals (lead, zinc, copper) dominant in the soil samples and minimal inhibitory concentration (MIC) of the heavy metals was determined with plate dilution method. Consequently, the bacterial isolates in this study possess plant growth-promoting traits and can ameliorate heavy metal contaminated soil. E. mundtii was reported to be found in heavy metal contaminated soil for the first time. This study is the first report about PGP characteristics (IAA production and phosphate solubilisation) of B. vallismortis.