Bacteria Halotolerant from Karst Sinkholes as a Source of Biosurfactants and Bioemulsifiers

Abstract

Halotolerant bacteria with biosurfactant (BS) and bioemulsifiers (BE) activity can coexist in Karstic sinkholes with marine influence. Two sinkholes in the Yucatan peninsula were selected to isolate bacteria with BE and BS activity stable in NaCl. The optimal time, the effect of nitrogen and carbon source in the medium, and the conditions (agitation, pH and salinity) for the production of BS and BE compounds in planktonic and sessile (stimulate the formation of biofilms in cell roller) culture were determined. Eighty strains showed the highest emulsification activity (EI24 ≥ 50%) and drop-collapse ≥ 4 mm. 87% of the strains are moderately halotolerant, and 21% bordered the limit of extreme halotolerance. Twenty-four strains maintained or improved their BS and BE activity under salinity conditions at 5% and 10%, being the most active genera Bacillus, Paenibacillus and Lysinibacillus, identified by sequencing of the 16S rRNA gene. The results show that the nitrogen source positively affects the BS and BE activity, regardless of the type of culture. The sessile culture markedly stimulated BS activity with significant differences. However, we did not find a greater influence on the culture conditions. The results suggest that halotolerant bacteria from sinkholes could be implemented in bioremediation and other biotechnological applications.

Broad-Spectrum Antifungal, Biosurfactants and Bioemulsifier Activity of Bacillus subtilis subsp. spizizenii—A Potential Biocontrol and Bioremediation Agent in Agriculture

“…The activity produced by B. subtilis MC6B-22 was detected by bioassays from 24 h of culture ( Table 4 ). The bioemulsifying activity continued to increase during the stationary phase until reaching a first peak of maximum activity at 84 h; after that, the activity declined at 96 h [ 39 ]. The production of antifungal and hemolytic compounds was evident from 36 to 120 h, finding the highest activity at 84 h, corresponding to the beginning of the death phase ( Figure 2 ).…”

“…In nature, iturin A is produced as a mixture of up to eight isomers named iturin A 2 -A 8 according to their types of βAA. The molecular masses of the isomers ranged from 1029 to 1084 [ 39 ]. The mycosubtilin and iturin A have almost the same structure, except that D-Ser 6 and L-Ans 7 residues in mycosubtilin are inverted to D-Ans 6 and L-Ser 7 in iturin [ 61 ].…”

Diversity and bioprospection of Gram-positive bacteria derived from a Mayan sinkhole

“…Despite exploration of bacterial communities from the underground river in Yucatán and its cenotes [29][30][31], there is little information on their biotechnological potential. By 2020, only 18 of the > 7000 mapped cenotes [1] had been assessed for their cultivable microbial diversity [3], and microorganisms from only six had been assessed for their biotechnological potential [3]; most studies have focused on inland cenotes, whereas the present study concerns a coastal cenote, Pol-Ac, with the aim of characterizing 49 Gram-positive bacteria isolated from sediment samples.…”

Biosurfactant Production by Bacillus amyloliquefaciens C11 and Streptomyces lavendulae C27 Isolated from a Biopurification System for Environmental Applications

“…strain isolated from lichens in the Amazon region [ 19 ], Pseudomonas isolated from CHL-enriched soil [ 23 ], Burkholderia sp. isolated from oil-contaminated soil [ 24 ], Bacillus amyloliquefaciens and Bacillus subtilis isolated from contaminated soil [ 20 ], Pseudomonas and Rhodococcus isolated from a pesticide treatment system [ 25 ] and oil spills [ 8 ], Bacillus and Pseudomonas isolated from weathered oil-contaminated soil containing heavy metals [ 26 ], B. subtilis isolated from marine soil sediment [ 27 ], and halotolerant bacteria isolated from karst sinkholes [ 28 ], among others.…”