Antimicrobial activity and resistance to heavy metals and antibiotics of heterotrophic bacteria isolated from sediment and soil samples collected from two Antarctic islands

Abstract

In this study, 24 Antarctic bacteria, isolated from sediment and soil samples from Deception and Galindez Islands, were characterized for their antimicrobial activity and response to 13 antibiotics and seven heavy metals. Multiple antibiotic resistance was observed for 67% of sediment isolates and 92% of soil isolates, suggesting medium anthropogenic impact in these Antarctic regions. The results revealed a varying response of the Antarctic bacteria to the tested heavy metals. All isolates showed multiple metal resistance towards two to six heavy metals, with minimum inhibitory concentrations ranging from 1.0 mM to 23.2 mM. The majority of the strains in both groups were resistant to lead, nickel, copper and zinc. Plasmids were detected in 21% of isolates. A consortium of highly metal-resistant bacteria could be developed with potential application for biological treatment of wastewaters. Strains that are highly sensitive to cadmium would be promising for developing biosensors to detect this highly toxic heavy metal in environmental samples. All Antarctic bacteria were found to inhibit the growth of one to all eight of the tested indicator bacteria, and 87% inhibited the growth of one to all four of the yeast indicator cultures. Promising psychrotolerant strains were detected as a valuable source of new antimicrobial compounds.

Insight into heavy metal resistome of soil psychrotolerant bacteria originating from King George Island (Antarctica)

“…Moreover, in 162 strains co-resistance (i.e., joint resistance to at least two toxic ions) phenotypes were revealed, which indicates that this phenomenon is not restricted to bacteria originating from the heavily contaminated regions. This high number of heavy metal-resistant bacteria in the Antarctic region may be surprising; however, it is in agreement with the results of other studies (De Souza et al 2006Tomova et al 2014Tomova et al , 2015. Moreover, the high incidence of resistance to heavy metals suggests that bacteria are able to cope and/or adapt to the occurrence of "pollutants" even in low humanimpacted environments (Lo Giudice et al 2013).…”

“…Studies of extreme, polar environments characterized by a still limited anthropogenic influence (e.g., High Arctic or Antarctica) are of great importance, as they may reveal novel genes encoding heavy metal-resistance and metabolism mechanisms, and show the role of naturally occurring microorganisms in biogeochemical cycles. The results of several studies revealed that bacteria isolated from various Arctic and Antarctic environments show resistances to various toxic, antimicrobial agents, such as antibiotics and heavy metals (De Souza et al 2006Lo Giudice et al 2013;Mangano et al 2014;Moller et al 2014;Tomova et al 2014;Perron et al 2015;Rahman et al 2015;Tomova et al 2015;González-Aravena et al 2016;Rodriguez-Rojas et al 2016). However, overall knowledge on the resistome of polar bacteria is still rather limited, and the lack of a systematic approach, combining chemical, microbiological, and molecular analyses, is apparent.…”

Revision of the currently authorised maximum copper content in complete feed

“…Such a correlation was also found in bacterial isolates from Antarctic shallow sediments where pollution from both chemicals and drugs is scarce (Lo Giudice et al., ). In sediments and soil samples collected from two Antarctic islands (Tomova et al., ), multiple antibiotic resistance was detected in 67% of the sediment isolates and 92% of the soil isolates. Most strains were resistant to copper (and lead, nickel and zinc).…”

Microbial Diversity of Browning Peninsula, Eastern Antarctica Revealed Using Molecular and Cultivation Methods

“…The biomass produced via the cultivation of microbes from extreme environments has led to the discovery of extracellular substances with antibacterial and/or antifungal properties (Gesheva, 2010; Gesheva and Negoita, 2011; Tomova et al, 2015). Additionally, the production of surfactants (glycolipids), the ability to grow on paraffin and naphthalene (Gesheva and Negoita, 2011) and their resistance to heavy metals (Tomova et al, 2015), highlights the potential for cold-adapted microbes to emulsify contaminants, such as hydrocarbons. Continued isolation of rare polar species could provide access to further strains for biotechnological applications, such as bioremediation and discovery of novel bioactive compounds, such as antibiotics (Tosi et al, 2010; Tytgat et al, 2014).…”