The genotypic diversity and lipase production of some thermophilic bacilli from different genera

Abstract Thermophilic 32 isolates and 20 reference bacilli were subjected to Rep-PCR and ITS-PCR fingerprinting for determination of their genotypic diversity, before screening lipase activities. By these methods, all the isolates and references could easily be differentiated up to subspecies level from each other. In screening assay, 11 isolates and 7 references were found to be lipase producing. Their extracellular lipase activities were measured quantitatively by incubating in both tributyrin and olive oil broths at 60 °C and pH 7.0. During the 24, 48 and 72-h period of incubation, the changes in the lipase activities, culture absorbance, wet weight of biomass and pH were all measured. The activity was determined by using pNPB in 50 mM phosphate buffer at pH 7.0 at 60 °C. The lipase production of the isolates in olive oil broths varied between 0.008 and 0.052, whereas these values were found to be 0.002-0.019 (U/mL) in the case of tyributyrin. For comparison, an index was established by dividing the lipase activities to cell biomass (U/mg). The maximum thermostable lipase production was achieved by the isolates F84a, F84b, and G. thermodenitrificans DSM 465T (0.009, 0.008 and 0.008 U/mg) within olive oil broth, whereas G. stearothermophilus A113 displayed the highest lipase activity than its type strain in tyributyrin. Therefore, as some of these isolates displayed higher activities in comparison to references, new lipase producing bacilli were determined by presenting their genotypic diversity with DNA fingerprinting techniques.

Anti-staphylococcal and antifungal substances produced by endospore-forming bacilli.

Some bacteria and fungi are related to deterioration and also transmission of foodborne diseases, emphasizing the need to search new substances that may act in the treatment and prevention of the illnesses transmitted by food. Strains from genus Bacillus produce a variety of substances with inhibitory activity that range from antibiotics to bacteriocins. In this work, three strains, identified as B. pasteurii (Pes1) and B. insolitus (Mam2 and Ame3) presented inhibitory action against staphylococcal strains isolated from food. Out of the 33 strains tested, 31 (94.0%) were inhibited by at least one of three main Bacillus producer strains, being most of them inhibited by strain Pes1, that also was able to inhibit filamentous fungi related to food spoilage. The antimicrobial substances produced by Pes1, Mam2 and Ame3 showed to be resistant to proteolytic enzymes, suggesting these substances have not an active proteinaceous compound, as typical bacteriocins. New studies are being performed to extract and characterize these antimicrobial agents to evaluate their potential application in biological control of microorganisms related to spoilage food and foodborne diseases.

The genetic diversity of genus Bacillus and the related genera revealed by 16S rRNA gene sequences and ardra analyses isolated from geothermal regions of turkey

Previously isolated 115 endospore-forming bacilli were basically grouped according to their temperature requirements for growth: the thermophiles (74%), the facultative thermophiles (14%) and the mesophiles (12%). These isolates were taken into 16S rRNA gene sequence analyses, and they were clustered among the 7 genera: Anoxybacillus, Aeribacillus, Bacillus, Brevibacillus, Geobacillus, Paenibacillus, and Thermoactinomycetes. Of these bacilli, only the thirty two isolates belonging to genera Bacillus (16), Brevibacillus (13), Paenibacillus (1) and Thermoactinomycetes (2) were selected and presented in this paper. The comparative sequence analyses revealed that the similarity values were ranged as 91.4-100 %, 91.8- 99.2 %, 92.6- 99.8 % and 90.7 - 99.8 % between the isolates and the related type strains from these four genera, respectively. Twenty nine of them were found to be related with the validly published type strains. The most abundant species was B. thermoruber with 9 isolates followed by B. pumilus (6), B. lichenformis (3), B. subtilis (3), B. agri (3), B. smithii (2), T. vulgaris (2) and finally P. barengoltzii (1). In addition, isolates of A391a, B51a and D295 were proposed as novel species as their 16S rRNA gene sequences displayed similarities ¡Ü 97% to their closely related type strains. The AluI-, HaeIII- and TaqI-ARDRA results were in congruence with the 16S rRNA gene sequence analyses. The ARDRA results allowed us to differentiate these isolates, and their discriminative restriction fragments were able to be determined. Some of their phenotypic characters and their amylase, chitinase and protease production were also studied and biotechnologically valuable enzyme producing isolates were introduced in order to use in further studies.

SPORE CELLULAR FATTY ACIDS ANALYSIS OF SOME AEROBIC ENDOSPORE-FORMING BACILLI / 微生物学通报

A gas chromatographic analysis method was employed to determine the cellular fatty acids (CFAs)profiles of the spores of some aerobic endospore forming bacilli.Purified spore cultures of 51 experimentas strains were processed to acquire whole cell fatty acids methyl esters for the subsequent gas chromatographic analysis,and the corresponding vegetative cells were set as control.The reproducibility study of spore fatty acids revealed that,the fatty acids components of spores were stable enough for research purpose,provided under standardized experimentas procedure.The dendrograms obtained by cluster analysis provided some meaningful taxonomic information of the experimental strains.The fatty acids analysis of spores seemed to be a promising supplementary tool for the chemotaxonomic research of aerobic endospore-forming bacilli.