Bacillus pumilus 15.1, a Strain Active against Ceratitis capitata, Contains a Novel Phage and a Phage-Related Particle with Bacteriocin Activity

A 98.1 Kb genomic region from B. pumilus 15.1, a strain isolated as an entomopathogen toward C. capitata, the Mediterranean fruit fly, has been characterised in search of potential virulence factors. The 98.1 Kb region shows a high number of phage-related protein-coding ORFs. Two regions with different phylogenetic origins, one with 28.7 Kb in size, highly conserved in Bacillus strains, and one with 60.2 Kb in size, scarcely found in Bacillus genomes are differentiated. The content of each region is thoroughly characterised using comparative studies. This study demonstrates that these two regions are responsible for the production, after mitomycin induction, of a phage-like particle that packages DNA from the host bacterium and a novel phage for B. pumilus, respectively. Both the phage-like particles and the novel phage are observed and characterised by TEM, and some of their structural proteins are identified by protein fingerprinting. In addition, it is found that the phage-like particle shows bacteriocin activity toward other B. pumilus strains. The effect of the phage-like particles and the phage in the toxicity of the strain toward C. capitata is also evaluated.

Lacticaseibacilli and Lactococci from Slovak Raw Goat Milk and their Potential

Strains potential such as bacteriocin activity, biofilm formation ability, growth in skim milk, susceptibility to antibiotics, tolerance to bile and low pH as well as enzyme production was tested in the species Lacticaseibacillus paracasei and Lactococcus lactis detected in Slovak raw goat milk. The strains showed mostly low-grade biofilm formation ability, susceptibility to antibiotics and sufficient tolerance to oxgall/bile. Lacticaseibacillus (Lcb.) paracasei ZM-1, ZM-2 and Lactococcus (Lc.) lactis PD MO 1/8 showed high tolerance to pH 3 (67 %, 83 % and 63 %, respectively). The strains showed bacteriocin activity against the principal indicator Enterococcus avium EA5 (inhibition zone ranging 5–24 mm). A concentrated substance of Lcb. paracasei LPa ML 12/1 (pH 6.3) inhibited EA5 strain (inhibition activity 100 AU ml–1). Lcb. paracasei ZM-1 and ZM-2 also produced a high amount of β-galactosidase (40 nmol). Although the strains indicated their beneficial potential, additional testing is needed; some tests are in processing for further possible application of selected strains in dairy.

Skrining Isolat Bakteri Asam Laktat Penghasil Bakteriosin yang Diisolasi dari Asinan Rebung Bambu Tabah dan Ketahanannya terhadap Panas

The aim of this study to determine the Lactic Acid Bacteria (LAB) isolated from pickled tabah bamboo shoots can produce bacteriocins and the resistance to heat. This research was conducted in two stages, namely: 1) Screening of LAB isolates producing bacteriocin and 2) Testing the effect of heating temperatures of 80°C, 100°C and 121°C for 5, 10 and 15 minutes and without heating to bacteriocin resistance activity. In this study, the screening stage was carried out in two stages, namely: 1) antibacterial test with cell free supernatant and 2) antibacterial test with neutralized cell free supernatant. The resulting clear zone is observed then followed by calculating the value of Arbitrary Units (AU). The bacteria used as an indicator is Lactobacillus plantarum which is Gram positive bacteria. The results of this study indicated that of 88 LAB isolates there were 27 isolates that were able to produce bacteriocin. From 27 isolates, there were three isolates with the most potential to produce bacteriocins, namely isolate PR.6.10.5 with an inhibition zone of 17.67 mm and a bacteriocin activity value of 264.81 mm2/ml, isolate PR.6.15.2 with an inhibition zone of 17.33 mm and the bacteriocin activity value of 259.57 mm2/ml and isolate PR.3.15.1 with an inhibition zone of 17.00 mm and a bacteriocin activity value of 254.34 mm2/ml. Bacteriocins from LAB isolates isolated from pickled tabah bamboo shoots were able to withstand heating to a temperature of 121°C for 15 minutes. Bacteriocin activity decreased by an average of 27.75% after heating at 80°C, 100°C and 121°C for 5,10 and 15 minutes with a bacteriocin activity value from 141.82 mm2/ml to 254.34 mm2/ml. The smallest decrease in activity value occurred in PR.6.10.5 isolates with an average decrease of 22.98%. Keywords: Screening, lactic acid bacteria (LAB), bacteriocin, heat.

Biotechnology for bacteriocin synthesis using photostimulation

This article presents results of a study of the effect of blue color on the bacteriocin activity. It was revealed that photostimulation of Lactobacillus Lactis with light in the blue spectrum (435-470 nm) with a light flux intensity of 1800 mcd for 50-60 minutes positively affects the bacteriocin activity (increases by 60.1%), while titer of the Lactobacillus lactis is 2 times higher. It was found that it was in the first 18 hours that the irradiated samples had a greater difference in terms of activity and titers than unirradiated samples. Oxidative stress affects the culture’s viability, both in samples treated with blue light and in the untreated cultures. However, impact intensity on the treated cultures is weaker. These outcomes indicate the possibility of using blue light for stimulating bacteriocin biosynthesis in order to use it as a food additive for prolongation of shelf life of food products.

Bacteriocin Activity of Lactic Acid Bacteria Isolated from Rumen Fluid of Thin Tail Sheep

The objective of this study was to determine the activity and the stability of bacteriocin from lactic acid bacteria (BAL) isolated from rumen fluid of thin-tail sheep under the temperature (80, 100, and 121°C), pH (3, 7, and 10), and the length of storage (for 2 weeks under the temperature -8, 11, and 29°C). Lactic acid bacteria obtained by isolation, selection, and identification of thin-tailed sheep rumen fluid were used for bacteriocin production. The crude bacteriocin was partially purified using 70% ammonium sulfate, then was dialysis for 12 hours. The obtained bacteriocin then tested its inhibitory activity against E.coli (representing Gram-negative) and S. aureus (representing Gram-positive) under temperature (80, 100, and 121°C), pH (3, 7, and 10), and the length of storage (for 2 weeks under the temperature -8, 11, and 29°C). The data of bacteriocin activity based on pH, temperature, and the length of storage were analyzed with factorial, then when there was a significant difference of variable because treatment was continued with Duncan's Multiple Range Test (DMRT) test. The results showed that the bacteriocin activity of the three types of BAL against S.aureus is greater than E.coli. The highest activity was shown in pH 3, while the lowest activity was shown at pH 10 (P<0.01). The highest activity was shown at a heating temperature of 100°C, while the lowest activity was shown at a heating temperature of 80°C (P<0.01). The activity of bacteriocin produced by BAL 0 A, BAL 1 A, and BAL 4 C tended to be stable to the heating temperature of 80, 100, and 121°C but decreased with increasing pH value (pH 3, 7, and 10). The best of bacteriocin activity was found at pH 3 (acid), heating at 100°C, and stored at -8°C for 14 days.