This study reports the biodiversity of thermophilic cellulolytic bacterial strains that present in the north Malaysian mangrove ecosystem. Soil samples were collected at the four most northern state of Malaysia (Perak, Pulau Pinang, Kedah and Perlis). The samples obtained were first enriched in nutrient broth at 45°C and 55°C prior culturing in the carboxymethylcellulose (CMC) agar medium. Repeated streaking was performed on the CMC agar to obtain a pure culture of each isolate prior subjecting it to hydrolysis capacity testing. The isolates that showing the cellulolytic zone (halozone) were sent for 16S rRNA sequencing. Total seven isolates (two from Perak, three from Kedah, another two were from Perlis and Penang each) showed halozone. The isolate (KFX-40) from Kedah exhibited highest halozone of 3.42 ± 0.58, meanwhile, the one obtained from Perak (AFZ-0) showed the lowest hydrolysis capacity (2.61 ± 0.10). Based on 16S rRNA sequencing results, 5 isolates (AFY-40, AFZ-0, KFX-40, RFY-20, and PFX-40) were determined to be
Anoxybacillus sp
. The other two isolates were identified as
Bacillus subtilis
(KFY-40) and
Paenibacillus dendritiformis
(KFX-0). Based on growth curve, doubling time of
Anoxybacillus sp
. UniMAP-KB06 was calculated to be 32.3 min. Optimal cellulose hydrolysis temperature and pH of this strain were determined to be 55°C and 6.0 respectively. Addition of Mg
2+
and Ca
2+
were found to enhance the cellulase activity while Fe
3+
acted as an enzyme inhibitor.
Acidithiobacillus thiooxidans is an acidophilic chemoautotrophic bacterium which capable to convert the toxic hydrogen sulphide in wastewater into non-toxic compounds. The Acidithiobacillus thiooxidans strain UniMAP-AIN01 was previously isolated from a local natural rubber latex processing mill. In this study, the A. thiooxidans strain UniMAP-AIN01 was subjected to its growth performance evaluation in the wastewater of natural rubber latex. The sulphur content in the wastewater was utilized as energy source and support their growth. It was discovered that the A. thiooxidans strain UniMAP-AIN01 has long doubling time of 2 days in thiosulphate medium, while log phase lasted until 6th day of incubation. Regression analysis of the growth kinetic was established with the aid of POLYMATH software. The precision value obtained as follows; linear regression, R2 of 0.9811, adjusted linear regression, Adj R2 of 0.9764, root mean square deviation, RMSD of 0.0015, and variance of 1.992 × 10−5 indicate the data is highly correlated and error is insignificant. Assessment on hydrogen sulphide removal efficiency using locally isolated A. thiooxidans strain UniMAP-AIN01 revealed 90% of hydrogen sulphide removal was achieved within a week.
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