grow at pH 11 and exhibiting antimicrobial activity against Staphylococcus aureus
and Bacillus subtilis were also isolated [104]. The same researchers isolated other
alkaliphiles which have shown significant activity against methicillin-resistant
S. aureus (MRSA) [105]. Facultative anaerobic haloalkaliphilic strains,
Alkalibacterium kapii ALK 6, Marinilactibacillus psychrotolerans ALK 9, and
Facklamia tabacinasalis ALK 1, were isolated from a smear ecosystem originating
from a commercial Raclette-type cheese and exhibited strong anti-listerial activity in
situ on cheese surface [106].
Physicochemical parameters like temperature, pH, incubation period, and
medium nutrients play a role in enhancing cell growth and increasing the yield of
the target product. The traditional “one-factor-at-a-time” (OFAT) technique was
used to increase the production of antibacterials of haloalkaliphilic actinomycetes
such as Streptomyces sannanensis strain RJT-1 [107], Streptomyces tanashiensis
strain A2D [108], Streptomyces aburaviensis Kut À8 [102, 103], Streptomyces
sp. EWC [109], and Streptomyces spp. AJ8 [110]. Important media components
affecting the antibacterial activity of the cyanobacteria, Synechocystis aquatilis,
were evaluated with the help of statistical Plackett-Burman design [111]. In the
study of Souagui et al. [112], antifungal production from Streptomyces sp. SY-BS5
was simultaneously optimized by the OFAT and response surface methodology,
using a Box-Behnken design. In addition to these preliminary screening studies
described above, there are reports on the production and detailed chemical characterization of a range of antibiotics produced by different alkaliphilic bacteria as
described below. Some of them may be of less practical value, because of repetition
of known molecules.
An aminoglycoside antibiotic substance isolated from Bacillus alkalophilishaggy
JY-827 showed not only an excellent dental anticaries activity but also no toxicity
against gingival cells when it was introduced into toothpaste. This substance was
suggested to replace chlorhexidine used in toothpastes and thus have a high potential
for commercial applications [113]. Dieter and co-workers identified pyrocoll (which
is known as a synthetic compound and constituent of cigarette smoke) to be one of
the metabolites produced by alkaliphilic Streptomyces sp. AK 409 from a steel waste
tip soil. The compound showed biological activity against various Arthrobacter
strains, filamentous fungi, several pathogenic protozoa, and some human tumor
cell lines [114]. Two metabolites from the culture filtrate of alkaliphilic Streptomyces
sanglieri AK 623 were structurally elucidated as lactonamycin Z, a new derivative of
lactonamycin, and its aglycone, lactonamycinone. Lactonamycin Z showed weak
activity against Gram-positive bacteria, but it strongly inhibited the proliferation of
gastric adenocarcinoma cells [115]. By using genetic data, instead of isolation, a
two-component new lantibiotic, haloduracin, was identified in the genome of the
Gram-positive alkaliphilic Bacillus halodurans C-125. Haloduracin was active
against a large number of Gram-positive bacteria, including many lactococci and
representative of Listeria, Streptococcus, Enterococcus, Bacillus, and Pediococcus
species. However, haloduracin did not owe activity against Gram-negative bacteria
[116]. Later on, an optimized production of haloduracin by another strain of Bacillus
halodurans was achieved by solid state fermentation [117].
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E. Khalikova et al.
and Bacillus subtilis were also isolated [104]. The same researchers isolated other
alkaliphiles which have shown significant activity against methicillin-resistant
S. aureus (MRSA) [105]. Facultative anaerobic haloalkaliphilic strains,
Alkalibacterium kapii ALK 6, Marinilactibacillus psychrotolerans ALK 9, and
Facklamia tabacinasalis ALK 1, were isolated from a smear ecosystem originating
from a commercial Raclette-type cheese and exhibited strong anti-listerial activity in
situ on cheese surface [106].
Physicochemical parameters like temperature, pH, incubation period, and
medium nutrients play a role in enhancing cell growth and increasing the yield of
the target product. The traditional “one-factor-at-a-time” (OFAT) technique was
used to increase the production of antibacterials of haloalkaliphilic actinomycetes
such as Streptomyces sannanensis strain RJT-1 [107], Streptomyces tanashiensis
strain A2D [108], Streptomyces aburaviensis Kut À8 [102, 103], Streptomyces
sp. EWC [109], and Streptomyces spp. AJ8 [110]. Important media components
affecting the antibacterial activity of the cyanobacteria, Synechocystis aquatilis,
were evaluated with the help of statistical Plackett-Burman design [111]. In the
study of Souagui et al. [112], antifungal production from Streptomyces sp. SY-BS5
was simultaneously optimized by the OFAT and response surface methodology,
using a Box-Behnken design. In addition to these preliminary screening studies
described above, there are reports on the production and detailed chemical characterization of a range of antibiotics produced by different alkaliphilic bacteria as
described below. Some of them may be of less practical value, because of repetition
of known molecules.
An aminoglycoside antibiotic substance isolated from Bacillus alkalophilishaggy
JY-827 showed not only an excellent dental anticaries activity but also no toxicity
against gingival cells when it was introduced into toothpaste. This substance was
suggested to replace chlorhexidine used in toothpastes and thus have a high potential
for commercial applications [113]. Dieter and co-workers identified pyrocoll (which
is known as a synthetic compound and constituent of cigarette smoke) to be one of
the metabolites produced by alkaliphilic Streptomyces sp. AK 409 from a steel waste
tip soil. The compound showed biological activity against various Arthrobacter
strains, filamentous fungi, several pathogenic protozoa, and some human tumor
cell lines [114]. Two metabolites from the culture filtrate of alkaliphilic Streptomyces
sanglieri AK 623 were structurally elucidated as lactonamycin Z, a new derivative of
lactonamycin, and its aglycone, lactonamycinone. Lactonamycin Z showed weak
activity against Gram-positive bacteria, but it strongly inhibited the proliferation of
gastric adenocarcinoma cells [115]. By using genetic data, instead of isolation, a
two-component new lantibiotic, haloduracin, was identified in the genome of the
Gram-positive alkaliphilic Bacillus halodurans C-125. Haloduracin was active
against a large number of Gram-positive bacteria, including many lactococci and
representative of Listeria, Streptococcus, Enterococcus, Bacillus, and Pediococcus
species. However, haloduracin did not owe activity against Gram-negative bacteria
[116]. Later on, an optimized production of haloduracin by another strain of Bacillus
halodurans was achieved by solid state fermentation [117].
182
E. Khalikova et al.