Novel Anoxybacillus flavithermus AK1: A Thermophile Isolated from a Hot Spring in Saudi Arabia

Molecular Characterization and Biofilm Formation Study of Contaminant Bacteria Isolated from Domiaty and Hungarian Cheeses in Jeddah City

The aim was to study the microbiological quality of Domiaty and Hungarian cheeses, molecular identification and biofilm formation of some selected contaminant bacteria. Samples were collected from two M and P big markets in Jeddah City through the period from February to October 2018, nine visits for two types of natural cheese. Results showed that the total bacterial counts (CFU/ml) from Domiaty cheese from two markets (M and P) were 0.1 x 105, 8 x 105 and 1 x 10 5 CFU/ml respectively (3 visits of M market) and 4 x 106, 0.4 x 106, 6.5 x 103, 1 x 103, 0.1 x 103 and 0.1 x 103 CFU/ml respectively (six samples from 6 visits from P market). Results showed that the total bacterial counts (CFU/ml) from Hungarian cheese were 1.5 x 10 5, 1x 10 4, 11 x 10 4 and 4 x10 6 CFU/ml respectively from (4 visits of M market) and 0.18 x 104, 3 x 106, 22 x 106, 6 x 106 and 5 x 104 CFU/ml respectively (5 visits from P market).Different bacterial isolates from cheese were identified by morphology and biochemical test. Bacterial isolates from cheeses were identified by VITEK MS as follow: Serratia liquefaciens (D6-1, D6-2, D14-1, D13-1 and D13-2), and Pseudomonas fluorescens (D14-2) were isolated from Domiaty cheese while Enterococcus faecium (H11-2), Serratia liquefaciens (H15-1) and Streptococcus thermophilus (H14-1) were isolated from Hungarian cheese. Some selected bacterial isolates were identified by 16S rRNA. Isolates were belong to MK757978 (Raoultilla terrigena (D15-1)), MK757979 (Bacillus cereus (D16-1)), MK757980 (Enterococcus faecalis (H10-2)), MK757982 (Enterococcus fiscalism (H11-1)), MK757981 (Serratia liquefactions (H13-1)), MK757984 (Anoxybacillus flavithermus (H17-1). All bacterial isolates have been tested for the formation of biofilm using a Tissue Culture Plate (TCP). Results revealed 12.5% and 46.15% of high biofilm formation respectively for bacterial isolates of Domiaty and Hungarian cheeses.

Genomic comparison of anoxybacillus flavithermus AK1, a thermophilic bacteria, with other strains

From ecological and industrial perspectives, Anoxybacillus flavithermus species that lives in a thermophilic environment, are extremely important bacteria due to their potential in producing highly interesting compounds and enzymes. In order to understand the genetic makeup of these thermophiles, we have performed a comparative genomics study of 12 genome-sequenced strains of Anoxybacillus flavithermus bacteria. The genome size of Anoxybacillus flavithermus strains is from 2.5Mbp to 3.7Mbp and on average containing a low percentage of G + C genomic content (˜41.9%). We show that, on the basis of the total gene-content, Anoxybacillus flavithermus strains are grouped in three different subgroups. In the future, it would be interesting to explore these strain subgroups to further understand the lifestyle of thermophilic bacteria. Focussing on the Anoxybacillus flavithermus AK1 strain, which was isolated from a Hot Spring in Saudi Arabia and closely related to A. flavithermus NBRC strain, we identified a unique list of 75 genes specific to AK1 strain, of which 63 of them have homologs in other taxonomically related species. We speculate that these AK1-specific genes might be resulted due to horizontal gene transfer from other bacteria in order to adapt to the extreme environmental conditions. Moreover, we predicted three potential secondary metabolite gene clusters in the AK1 strain that further need to be experimentally characterised. Genomic annotation, secondary metabolite gene clusters and outcomes of the strain genomic comparisons from this study would be the basis for the strain-specific mathematical model for exploiting the metabolism for the industrial and ecological applications.