15.2 Photobiological Agents and Methods Used in PhotoBiological Reactors

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was achieved in both PSBRs (photoperiods of 24 hours continuous illumination

and 16 hours/8 hours L/D). Longer lighting period favored the growth of biomass,

which resulted in 43% more total organic carbon (TOC) production in the same

photoperiod. It demonstrates that the use of algae–bacteria consortia requires less

energy to treat NH4

+-N-loaded wastewater, and this method should be further

enhanced to make it more sustainable and cost-effective [14].

15.2.1.13

Detection of sul1 and sul2 Genes in Sulfonamide-Resistant Bacteria

(SRB) from Sewage, Aquaculture Sources, Animal Wastes, and Hospital

Wastewater

The extensive use of antibiotics has placed a lot of selective pressure on bacteria of

different environments. Recent study aimed at detecting the occurrence of sulfon-

amide resistance genes and antibiogram of sulfonamide-resistant bacteria (SRB)

isolated from sewage, aquaculture sources, animal wastes, and hospital wastewater.

In this method, SRB were isolated on medium incorporated with sulfadiazine (SDZ).

Antibiotic susceptibility was carried out using disc diffusion method, and detection

of sul1, sul2, and sul3 genes was done by polymerase chain reaction (PCR) using

specific primers. The results showed 48 SRBs, out of which 8 were from aquaculture,

16 from animal wastes, 10 from hospital wastewater, and 14 from sewage. They

belong to 16 genera with Pseudomonas spp. and Bacillus spp. In the Gram-negative

SRB, there was 100% resistance to ertapenem, tetracycline (77.5%), ampicillin

(75%), cefpodoxime (47.5%), streptomycin (27.5%), amoxicillin-clavulanate (22.5%),

ciprofloxacin (22.5%), imipenem (15%), cefotaxime (12.5%), and ceftazidime (7.5%),

and in Gram-positive SRB, there was 100% resistance to ampicillin, tetracycline, and

ertapenem while 50% resistance to cefpodoxime and 12.5% resistance to imipenem,

and no resistance was observed to amoxicillin-clavulanate and ciprofloxacin. Most

(85.4%; 41 out of 48) of the SRB were multidrug resistant (MDR). The sul1 was

noticed in P. aeruginosa H19A (isolated from hospital wastewater), Bacillus sp.

AQE3 (aquaculture pond), and Leclercia sp. S5C (sewage) while sul2 was detected

in P. aeruginosa PG4A (animal waste) and Klebsiella sp. S6C (sewage). None of

the SRB harbored sul3, and no co-occurrence of the sul genes was observed. The

source sampled in the study is an important media for the proliferation of MDR

bacteria and resistance genes and revealed a high pervasiveness of MDR SRB in

hospital wastewater, sewage, animal wastes, and aquaculture wastewater. More

studies should be carried out on other potential antibiotic reservoirs and environ-

ments for the discovery of novel sulfonamide resistance genes and the molecular

characteristics of isolates possessing these genes [15].

15.2.1.14

Photosynthetic Bacteria as a Potential Alternative to Meet

Sustainable Wastewater Treatment Requirement

Conventional activated sludge (CAS) process as the core to wastewater treatment

is challenged with severe problems such as high energy consumption, sludge

disposal, and inevitable greenhouse gas emission, which will posture a grave impact

on the present wastewater industry. Photosynthetic bacteria (PSB) serve as an

alternative to these impacts and have flexible metabolic modes and high tolerance,